| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Carvalho, Carla, 1988-
(författare)
-
The Role of Kidney Oxygen Homeostasis for the Development of Kidney Disease
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The relation between oxygen supply and demand determines tissue oxygen tension (PO2). When intrarenal tissue PO2 decreases, any compensatory increase in oxygen supply via increased renal blood flow is likely to increase glomerular filtration rate. The resulting increased tubular load of electrolytes destined for active transport increases oxygen consumption, thus affecting intrarenal tissue PO2. Consequently, the kidney is particularly sensitive to alterations in oxygen homeostasis and kidney hypoxia is acknowledged as a common pathway to end stage renal disease. Different factors that can affect intrarenal oxygen homeostasis, including alterations in blood pressure and sodium intake dietary or pathologies such as diabetes mellitus, anemia or atherosclerosis. This thesis focuses on understanding how these factors influence kidney oxygen homeostasis.Pronounced reduction in sodium intake caused tissue hypoxia in kidney cortex via activation of the renin-angiotensin-aldosterone leading to increased tubular sodium reabsorption. Angiotensin II and aldosterone affect kidney oxygen handling differently. Whereas angiotensin II mainly affects kidney oxygen delivery, aldosterone mainly affects oxygen consumption.The hypoxia-inducible factor (HIF) system is a cellular defense mechanism against prolonged hypoxia. Although diabetes causes intrarenal hypoxia, hyperglycemia per se also prevents HIF-activation. Therefore, the effects of type 1 diabetes were evaluated in genetically modified mice with chronic HIF-activation. Diabetic mice with globally increased HIF activity, due to heterozygote prolyl hydroxylase-2 deficiency, displayed reduced mitochondria leak respiration and preserved cortical PO2. Diabetic mice with kidney-specific HIF activation, due to homozygous deficiency of von Hippel-Lindau, developed reduced mitochondria leak respiration and reduced urinary albumin excretion.The normal age-related decline in kidney function has been proposed to be due to, at least in part, increased oxidative stress, which can induce mitochondrial leak respiration via activation of uncoupling proteins. Indeed, two-year old mice deficient of uncoupling protein-2 presented with improved mitochondria efficiency and reduced urinary protein excretion.Summarizing, the data presented in this thesis provide clear support for potent influence of the renin-angiotensin-aldosterone system, HIF activation and mitochondria function on intrarenal oxygen availability. Maintaining kidney oxygen homeostasis may be a unifying strategy to protect kidney function.
|
|
| 6. |
|
|
| 7. |
- Cat, Aurelie Nguyen Dinh, et al.
(författare)
-
Vascular dysfunction in obese diabetic db/db mice involves the interplay between aldosterone/mineralocorticoid receptor and Rho kinase signaling
- 2018
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Activation of aldosterone/mineralocorticoid receptors (MR) has been implicated in vascular dysfunction of diabetes. Underlying mechanisms are elusive. Therefore, we investigated the role of Rho kinase (ROCK) in aldosterone/MR signaling and vascular dysfunction in a model of diabetes. Diabetic obese mice (db/db) and control counterparts (db/+) were treated with MR antagonist (MRA, potassium canrenoate, 30 mg/kg/day, 4 weeks) or ROCK inhibitor, fasudil (30 mg/kg/day, 3 weeks). Plasma aldosterone was increased in db/db versus db/+. This was associated with enhanced vascular MR signaling. Norepinephrine (NE)-induced contraction was increased in arteries from db/db mice. These responses were attenuated in mice treated with canrenoate or fasudil. Db/db mice displayed hypertrophic remodeling and increased arterial stiffness, improved by MR blockade. Vascular calcium sensitivity was similar between depolarized arteries from db/+ and db/db. Vascular hypercontractility in db/db mice was associated with increased myosin light chain phosphorylation and reduced expression of PKG-1 alpha. Vascular RhoA/ROCK signaling and expression of pro-inflammatory and pro-fibrotic markers were exaggerated in db/db mice, effects that were attenuated by MRA. Fasudil, but not MRA, improved vascular insulin sensitivity in db/db mice, evidenced by normalization of Irs1 phosphorylation. Our data identify novel pathways involving MR-RhoA/ROCK-PKG-1 that underlie vascular dysfunction and injury in diabetic mice.
|
|
| 8. |
- Franzen, Stephanie, et al.
(författare)
-
Differences in susceptibility to develop parameters of diabetic nephropathy in four mouse strains with type 1 diabetes
- 2014
-
Ingår i: American Journal of Physiology-Renal Physiology. - : American Physiological Society. - 1931-857X .- 1522-1466. ; 306:10, s. F1171-F1178
-
Tidskriftsartikel (refereegranskat)abstract
- One-third of diabetes mellitus patients develop diabetic nephropathy, and with underlying mechanisms unknown it is imperative that diabetic animal models resemble human disease. The present study investigated the susceptibility to develop diabetic nephropathy in four commonly used and commercially available mouse strains with type 1 diabetes to determine the suitability of each strain. Type 1 diabetes was induced in C57Bl/6, NMRI, BALB/c, and 129Sv mice by alloxan, and conscious glomerular filtration rate, proteinuria, and oxidative stress levels were measured in control and diabetic animals at baseline and after 5 and 10 wk. Histological alterations were analyzed using periodic acid-Schiff staining. Diabetic C57Bl/6 displayed increased glomerular filtration rate, i.e., hyperfiltration, whereas all other parameters remained unchanged. Diabetic NMRI developed the most pronounced hyperfiltration as well as increased oxidative stress and proteinuria but without glomerular damage. Diabetic BALB/c did not develop hyperfiltration but presented with pronounced proteinuria, increased oxidative stress, and glomerular damage. Diabetic 129Sv displayed proteinuria and increased oxidative stress without glomerular hyperfiltration or damage. However, all strains displayed intras-train correlation between oxidative stress and proteinuria. In conclusion, diabetic C57Bl/6 and NMRI both developed glomerular hyperfiltration but neither presented with histological damage, although NMRI developed low-degree proteinuria. Thus these strains may be suitable when investigating the mechanism causing hyperfiltration. Neither BALB/c nor 129Sv developed hyperfiltration although both developed pronounced proteinuria. However, only BALB/c developed detectable histological damage. Thus BALB/c may be suitable when studying the roles of proteinuria and histological alterations for the progression of diabetic nephropathy.
|
|
| 9. |
- Friederich, Malou, 1983-, et al.
(författare)
-
Deletion of Uncoupling Protein-2 reduces renal mitochondrial leak respiration, intrarenal hypoxia and proteinuria in a mouse model of type 1 diabetes
- 2018
-
Ingår i: Acta Physiologica. - : WILEY. - 1748-1708 .- 1748-1716. ; 223:4
-
Tidskriftsartikel (refereegranskat)abstract
- AimUncoupling protein-2 (UCP-2) can induce mitochondrial uncoupling in the diabetic kidney. Although mitochondrial uncoupling reduces oxidative stress originating from the mitochondria and can be regarded as a protective mechanism, the increased oxygen consumption occurring secondarily to increased mitochondria uncoupling, that is leak respiration, may contribute to kidney tissue hypoxia. Using UCP-2(-/-) mice, we tested the hypothesis that UCP-2-mediated leak respiration is important for the development of diabetes-induced intrarenal hypoxia and proteinuria. MethodsKidney function, invivo oxygen metabolism, urinary protein leakage and mitochondrial function were determined in wild-type and UCP-2(-/-) mice during normoglycaemia and 2weeks after diabetes induction. ResultsDiabetic wild-type mice displayed mitochondrial leak respiration, pronounced intrarenal hypoxia, proteinuria and increased urinary KIM-1 excretion. However, diabetic UCP-2(-/-) mice did not develop increased mitochondrial leak respiration and presented with normal intrarenal oxygen levels, urinary protein and KIM-1 excretion. ConclusionAlthough functioning as an antioxidant system, mitochondria uncoupling is always in co-occurrence with increased oxygen consumption, that is leak respiration; a potentially detrimental side effect as it can result in kidney tissue hypoxia; an acknowledged unifying pathway to nephropathy. Indeed, this study demonstrates a novel mechanism in which UCP-2-mediated mitochondrial leak respiration is necessary for the development of diabetes-induced intrarenal tissue hypoxia and proteinuria.
|
|
| 10. |
- Friederich, Malou, et al.
(författare)
-
Diabetes-induced up-regulation of uncoupling protein-2 results in increased mitochondrial uncoupling in kidney proximal tubular cells
- 2008
-
Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 1878-2434 .- 0005-2728. ; 1777:7-8, s. 935-940
-
Tidskriftsartikel (refereegranskat)abstract
- We have previously reported increased O(2) consumption unrelated to active transport by tubular cells and up-regulated mitochondrial uncoupling protein (UCP)-2 expressions in diabetic kidneys. It is presently unknown if the increased UCP-2 levels in the diabetic kidney results in mitochondrial uncoupling and increased O(2) consumption, which we therefore investigated in this study. The presence of UCP-2 in proximal tubular cells was confirmed by immunohistochemistry and found to be increased (western blot) in homogenized tissue and isolated mitochondria from kidney cortex of diabetic rats. Isolated proximal tubular cells had increased total and ouabain-insensitive O(2) consumption compared to controls. Isolated mitochondria from diabetic animals displayed increased glutamate-stimulated O(2) consumption (in the absence of ADP and during inhibition of the ATP-synthase by oligomycin) compared to controls. Guanosine diphosphate, an UCP inhibitor, and bovine serum albumin which removes fatty acids that are essential for UCP-2 uncoupling activity, independently prevented the increased glutamate-stimulated O(2) consumption in mitochondria from diabetic animals. In conclusion, diabetic rats have increased mitochondrial UCP-2 expression in renal proximal tubular cells, which results in mitochondrial uncoupling and increased O(2) consumption. This mechanism may be protective against diabetes-induced oxidative stress, but will increase O(2) usage. The subsequently reduced O(2) availability may contribute to diabetes-induced progressive kidney damage.
|
|
| 11. |
- Friederich, Malou, et al.
(författare)
-
Diabetes, oxidative stress, nitric oxide and mitochondria function
- 2009
-
Ingår i: Current diabetes reviews. - 1875-6417. ; 5:2, s. 120-144
-
Tidskriftsartikel (refereegranskat)abstract
- The role of altered mitochondria function has recently emerged as an important mechanism for the development of diabetic complications. Altered mitochondria function has also been implicated in the ageing process, defective insulin secretion, hypertension, arteriosclerosis, ischemia-reperfusion injury and apoptosis. Normally, the mitochondria are associated with ATP production using primarily pyruvate as the substrate, but recent reports indicate that tissue specific preferences exist. Also, the mitochondria are a substantial source of superoxide production, preferentially during states of elevated intracellular glucose concentrations. The mitochondria function is regulated by several factors including nitric oxide, oxidative stress, mammalian target of rapamycin, ADP and P(i) availability, which result in a complex regulation of ATP production and oxygen consumption, but also superoxide generation. These factors seem to be tissue specific, which warrants a more diverse mechanistic model applying to that specific tissue or cell type. This review presents the basic functions of the mitochondria and focuses on the complex interplay between oxidative stress, nitric oxide and uncoupling proteins in regulating mitochondria function with special focus on diabetes-induced alterations occurring on the mitochondria level.
|
|
| 12. |
- Friederich, Malou, 1983-, et al.
(författare)
-
Identification and distribution of uncoupling protein isoforms in the normal and diabetic rat kidney
- 2009
-
Ingår i: Advances in Experimental Medicine and Biology. - New York : Springer. - 0065-2598 .- 2214-8019. - 9780387859972 ; 645, s. 205-212
-
Tidskriftsartikel (refereegranskat)abstract
- Uncoupling protein (UCP)-2 and -3 are ubiquitously expressed throughout the body but there is currently no information regarding the expression and distribution of the different UCP isoforms in the kidney. Due to the known cross-reactivity of the antibodies presently available for detection of UCP-2 and -3 proteins, we measured the mRNA expression of UCP-1, -2 and -3 in the rat kidney in order to detect the kidney-specific UCP isoforms. Thereafter, we determined the intrarenal distribution of the detected UCP isoforms using immunohistochemistry. Thereafter, we compared the protein levels in control and streptozotocin-induced diabetic rats using Western blot. Expressions of the UCP isoforms were also performed in brown adipose tissue and heart as positive controls for UCP-1 and 3, respectively. UCP-2 mRNA was the only isoform detected in the kidney. UCP-2 protein expression in the kidney cortex was localized to proximal tubular cells, but not glomerulus or distal nephron. In the medulla, UCP-2 was localized to cells of the medullary thick ascending loop of Henle, but not to the vasculature or parts of the nephron located in the inner medulla. Western blot showed that diabetic kidneys have about 2.5-fold higher UCP-2 levels compared to controls. In conclusion, UCP-2 is the only isoform detectable in the kidney and UCP-2 protein can be detected in proximal tubular cells and cells of the medullary thick ascending loop of Henle. Furthermore, diabetic rats have increased UCP-2 levels compared to controls, but the mechanisms underlying this increase and its consequences warrants further studies.
|
|
| 13. |
- Friederich, Malou, et al.
(författare)
-
Uncoupling protein-2 in diabetic kidneys : increased protein expression correlates to increased non-transport related oxygen consumption
- 2008
-
Ingår i: Advances in Experimental Medicine and Biology. - Boston, MA : Springer Berlin/Heidelberg. - 0065-2598 .- 2214-8019. ; 614, s. 37-43, s. 37-43
-
Tidskriftsartikel (refereegranskat)abstract
- Diabetic patients have an elevated risk to develop renal dysfunction and it has been postulated that altered energy metabolism is involved. We have previously shown that diabetic rats have markedly decreased oxygen availability in the kidney, resulting from increased oxygen consumption. A substantial part of the increased oxygen consumption is unrelated to tubular transport, suggesting decreased mitochondrial efficiency. In this study, we investigated the protein expression of mitochondrial uncoupling protein (UCP)-2 in kidney tissue from control and streptozotocin (STZ)-induced diabetic rats. Protein levels of UCP-2 were measured in adult male control and STZ-diabetic Wistar Furth as well as Sprague Dawley rats in both the kidney cortex and medulla by Western blot technique. Two weeks of hyperglycemia resulted in increased protein levels of UCP-2 in kidneys from both Wistar Furth and Sprague Dawley rats. Both cortical and medullary UCP-2 levels were elevated 2-3 fold above control levels. We conclude that sustained STZ-induced hyperglycemia increases the kidney levels of mitochondrial UCP-2, which could explain the previously reported increase in non-transport related oxygen consumption in diabetic kidneys. The elevated UCP-2 levels may represent an effort to reduce the increased production of superoxide radicals which is evident during diabetes.
|
|
| 14. |
- Friederich Persson, Malou, et al.
(författare)
-
Acute knockdown of uncoupling protein-2 increases mitochondria uncoupling via the adenine nucleotide transporter and decreases oxidative stress in diabetic kidneys
- 2012
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7, s. e39635-
-
Tidskriftsartikel (refereegranskat)abstract
- Increased O2 metabolism resulting in chronic hypoxia is common in models of endstage renal disease. Mitochondrial uncoupling increases O2 consumption but the ensuing reduction in mitochondrial membrane potential may limit excessive oxidative stress. The present study addressed the hypothesis that mitochondrial uncoupling regulates mitochondria function and oxidative stress in the diabetic kidney. Isolated mitochondria from kidney cortex of control and streptozotocin-induced diabetic rats were studied before and after siRNA knockdown of uncoupling protein-2 (UCP-2). Diabetes resulted in increased UCP-2 protein expression and UCP-2-mediated uncoupling, but normal mitochondria membrane potential. This uncoupling was inhibited by GDP, which also increased the membrane potential. siRNA reduced UCP-2 protein expression in controls and diabetics (−30–50%), but paradoxically further increased uncoupling and markedly reduced the membrane potential. This siRNA mediated uncoupling was unaffected by GDP but was blocked by ADP and carboxyatractylate (CAT). Mitochondria membrane potential after UCP-2 siRNA was unaffected by GDP but increased by CAT. This demonstrated that further increased mitochondria uncoupling after siRNA towards UCP-2 is mediated through the adenine nucleotide transporter (ANT). The increased oxidative stress in the diabetic kidney, manifested as increased thiobarbituric acids, was reduced by knocking down UCP-2 whereas whole-body oxidative stress, manifested as increased circulating malondialdehyde, remained unaffected. All parameters investigated were unaffected by scrambled siRNA. In conclusion, mitochondrial uncoupling via UCP-2 regulates mitochondria membrane potential in diabetes. However, blockade of the diabetes-induced upregulation of UCP- 2 results in excessive uncoupling and reduced oxidative stress in the kidney via activation of ANT.
|
|
| 15. |
- Friederich-Persson, Malou, et al.
(författare)
-
Acute Knockdown of Uncoupling Protein-2 Increases Uncoupling via the Adenine Nucleotide Transporter and Decreases Oxidative Stress in Diabetic Kidneys
- 2012
-
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7, s. e39635-
-
Tidskriftsartikel (refereegranskat)abstract
- Increased O(2) metabolism resulting in chronic hypoxia is common in models of endstage renal disease. Mitochondrial uncoupling increases O(2) consumption but the ensuing reduction in mitochondrial membrane potential may limit excessive oxidative stress. The present study addressed the hypothesis that mitochondrial uncoupling regulates mitochondria function and oxidative stress in the diabetic kidney. Isolated mitochondria from kidney cortex of control and streptozotocin-induced diabetic rats were studied before and after siRNA knockdown of uncoupling protein-2 (UCP-2). Diabetes resulted in increased UCP-2 protein expression and UCP-2-mediated uncoupling, but normal mitochondria membrane potential. This uncoupling was inhibited by GDP, which also increased the membrane potential. siRNA reduced UCP-2 protein expression in controls and diabetics (-30-50%), but paradoxically further increased uncoupling and markedly reduced the membrane potential. This siRNA mediated uncoupling was unaffected by GDP but was blocked by ADP and carboxyatractylate (CAT). Mitochondria membrane potential after UCP-2 siRNA was unaffected by GDP but increased by CAT. This demonstrated that further increased mitochondria uncoupling after siRNA towards UCP-2 is mediated through the adenine nucleotide transporter (ANT). The increased oxidative stress in the diabetic kidney, manifested as increased thiobarbituric acids, was reduced by knocking down UCP-2 whereas whole-body oxidative stress, manifested as increased circulating malondialdehyde, remained unaffected. All parameters investigated were unaffected by scrambled siRNA. In conclusion, mitochondrial uncoupling via UCP-2 regulates mitochondria membrane potential in diabetes. However, blockade of the diabetes-induced upregulation of UCP- 2 results in excessive uncoupling and reduced oxidative stress in the kidney via activation of ANT.
|
|
| 16. |
- Friederich-Persson, Malou, et al.
(författare)
-
Angiotensin II Reduces Transport-Dependent Oxygen Consumption but Increases Transport-Independent Oxygen Consumption in Immortalized Mouse Proximal Tubular Cells
- 2014
-
Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer New York. - 0065-2598 .- 2214-8019. - 9781493906208 - 9781493905836 ; 812, s. 157-163
-
Tidskriftsartikel (refereegranskat)abstract
- Oxidative stress is closely associated with renal dysfunction following diabetes and hypertension. Angiotensin II (Ang II) can activate the NADPH-oxidase, increasing oxidative stress that is thought to blunt proximal tubular electrolyte transport and thereby oxygen consumption (QO(2)). We investigated the effect of Ang II on QO(2) in immortalized mouse proximal tubular cells over-expressing the NADPH oxidase subunit p22(phox); a model of increased oxidative stress. Cultured cells were exposed to either Ang II or H2O2 for 48 h. QO(2) was determined during baseline (113 mmol/l NaCl; transport-dependent QO(2)) and during sodium-free conditions (transport-independent QO(2)). Ang II reduced transport-dependent QO(2) in wild-types, but not in p22(phox) which also displayed increased QO(2) at baseline. Transport-independent QO(2) was increased in p22(phox) and Ang II had no additional effect, whereas it increased QO(2) in wild-type. Addition of H2O2 reduced transport-dependent QO(2) in wild-types, but not in p22(phox). Transport-independent QO(2) was unaffected by H2O2. The similar effects of Ang II and H2O2 to reduce transport-dependent QO(2) suggest a direct regulatory role of oxidative stress. In accordance, the transport-dependent QO(2) was reduced in p22(phox) already during baseline. The effects of Ang II on transport-independent QO(2) was not replicated by H2O2, indicating direct regulation via Ang II-receptors independently of oxidative stress. However, the Ang II effect was absent in p22(phox), suggesting that oxidative stress also modulates normal Ang II signaling. In conclusion, Ang II affects both transport-dependent and transport-independent QO(2) in proximal tubular cells and may be an important pathway modulating renal QO(2).
|
|
| 17. |
- Friederich Persson, Malou, et al.
(författare)
-
Coenzyme Q10 prevents GDP-sensitive mitochondrial uncoupling, glomerular hyperfiltration and proteinuria in kidneys from db/db mice as a model of type 2 diabetes
- 2012
-
Ingår i: Diabetologia. - : Springer Verlag (Germany). - 0012-186X .- 1432-0428. ; 55:5, s. 1535-1543
-
Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Increased oxygen consumption results in kidney tissue hypoxia, which is proposed to contribute to the development of diabetic nephropathy. Oxidative stress causes increased oxygen consumption in type 1 diabetic kidneys, partly mediated by uncoupling protein-2 (UCP-2)-induced mitochondrial uncoupling. The present study investigates the role of UCP-2 and oxidative stress in mitochondrial oxygen consumption and kidney function in db/db mice as a model of type 2 diabetes. Methods Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment.Results Untreated db/db mice displayed mitochondrial uncoupling, manifested as glutamate-stimulated oxygen consumption (2.7 ± 0.1 vs 0.2 ± 0.1 pmol O2 s−1 [mg protein]−1), glomerular hyperfiltration (502 ± 26 vs 385 ± 3 μl/min), increased proteinuria (21 ± 2 vs 14 ± 1, μg/24 h), mitochondrial fragmentation (fragmentation score 2.4 ± 0.3 vs 0.7 ± 0.1) and size (1.6 ± 0.1 vs 1 ± 0.0 μm) compared with untreated controls. All alterations were prevented or reduced by CoQ10 treatment. Mitochondrial uncoupling was partly inhibited by the UCP inhibitor GDP (−1.1 ± 0.1 pmol O2 s−1 [mg protein]−1). UCP-2 protein levels were similar in untreated control and db/db mice (67 ± 9 vs 67 ± 4 optical density; OD) but were reduced in CoQ10 treated groups (43 ± 2 and 38 ± 7 OD).Conclusions/interpretation db/db mice displayed oxidative stress-mediated activation of UCP-2, which resulted in mitochondrial uncoupling and increased oxygen consumption. CoQ10 prevented altered mitochondrial function and morphology, glomerular hyperfiltration and proteinuria in db/db mice, highlighting the role of mitochondria in the pathogenesis of diabetic nephropathy and the benefits of preventing increased oxidative stress.
|
|
| 18. |
- Friederich-Persson, Malou, et al.
(författare)
-
Increased kidney metabolism as a pathway to kidney tissue hypoxia and damage : effects of triiodothyronine and dinitrophenol in normoglycemic rats.
- 2013
-
Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer-Verlag New York. - 0065-2598 .- 2214-8019. - 9781461474111 - 9781461472568 ; 789, s. 9-14
-
Tidskriftsartikel (refereegranskat)abstract
- Intrarenal tissue hypoxia is an acknowledged common pathway to end-stage renal disease in clinically common conditions associated with development of chronic kidney disease, such as diabetes and hypertension. In diabetic kidneys, increased oxygen metabolism mediated by mitochondrial uncoupling results in decreased kidney oxygen tension (PO2) and contributes to the development of diabetic nephropathy. The present study investigated whether increased intrarenal oxygen metabolism per se can cause intrarenal tissue hypoxia and kidney damage, independently of confounding factors such as hyperglycemia and oxidative stress. Male Sprague-Dawley rats were untreated or treated with either triiodothyronine (T3, 10 g/kg bw/day, subcutaneously for 10 days) or the mitochondria uncoupler dinitrophenol (DNP, 30 mg/kg bw/day, oral gavage for 14 days), after which in vivo kidney function was evaluated in terms of glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, Transonic, PAH clearance), cortical PO2 (Clark-type electrodes), kidney oxygen consumption (QO2), and proteinuria. Administration of both T3 and DNP increased kidney QO2 and decreased PO2 which resulted in proteinuria. However, GFR and RBF were unaltered by either treatment. The present study demonstrates that increased kidney metabolism per se can cause intrarenal tissue hypoxia which results in proteinuria. Increased kidney QO2 and concomitantly reduced PO2 may therefore be a mechanism for the development of chronic kidney disease and progression to end-stage renal disease.
|
|
| 19. |
|
|
| 20. |
- Friederich-Persson, Malou, et al.
(författare)
-
Kidney Hypoxia, Attributable to Increased Oxygen Consumption, Induces Nephropathy Independently of Hyperglycemia and Oxidative Stress
- 2013
-
Ingår i: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 62:5, s. 914-919
-
Tidskriftsartikel (refereegranskat)abstract
- Diabetic nephropathy is strongly associated with both increased oxidative stress and kidney tissue hypoxia. The increased oxidative stress causes increased kidney oxygen consumption resulting in kidney tissue hypoxia. To date, it has been difficult to determine the role of kidney hypoxia, per se, for the development of nephropathy. We tested the hypothesis that kidney hypoxia, without confounding factors such as hyperglycemia or elevated oxidative stress, results in nephropathy. To induce kidney hypoxia, dinitrophenol (30 mg per day per kg bodyweight by gavage), a mitochondrial uncoupler that increases oxygen consumption and causes kidney hypoxia, was administered for 30 consecutive days to rats. Thereafter, glomerular filtration rate, renal blood flow, kidney oxygen consumption, kidney oxygen tension, kidney concentrations of glucose and glycogen, markers of oxidative stress, urinary protein excretion, and histological findings were determined and compared with vehicle-treated controls. Dinitrophenol did not affect arterial blood pressure, renal blood flow, glomerular filtration rate, blood glucose, or markers of oxidative stress but increased kidney oxygen consumption, and reduced cortical and medullary concentrations of glucose and glycogen, and resulted in intrarenal tissue hypoxia. Furthermore, dinitrophenol treatment increased urinary protein excretion, kidney vimentin expression, and infiltration of inflammatory cells. In conclusion, increased mitochondrial oxygen consumption results in kidney hypoxia and subsequent nephropathy. Importantly, these results demonstrate that kidney tissue hypoxia, per se, without confounding hyperglycemia or oxidative stress, may be sufficient to initiate the development of nephropathy and therefore demonstrate a new interventional target for treating kidney disease.
|
|
| 21. |
- Friederich-Persson, Malou, 1983-, et al.
(författare)
-
Mitochondrial angiotensin II receptors regulate oxygen consumption in kidney mitochondria from healthy and type 1 diabetic rats.
- 2020
-
Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 1931-857X .- 1522-1466. ; 318:3, s. 683-688
-
Tidskriftsartikel (refereegranskat)abstract
- Exaggerated activation of the renin-angiotensin-aldosterone system (RAAS) is a key feature in diseases such as hypertension, diabetes, and chronic kidney disease. Recently, an intracellular RAAS was demonstrated with angiotensin II (ANG II) type 1 (AT1) and type 2 (AT2) receptors expressed in nuclei and mitochondria. Diabetes is associated with both mitochondrial dysfunction and increased intracellular ANG II concentration in the kidney cortex. The present study investigated the role of ANG II signaling in kidney cortex mitochondria isolated from control and streptozotocin-induced diabetic rats. Mitochondrial oxygen consumption was evaluated after addition of ANG II alone or after preincubation with candesartan (AT1 receptor antagonist), PD-123319 (AT2 receptor antagonist), or the two in combination. ANG II binds to only mitochondrial AT2 receptors in control rats and both AT1 receptors and AT2 receptors in diabetic rats. ANG II decreased oxygen consumption in mitochondria from both control and diabetic rats. ANG II response was reversed to increased oxygen consumption by the nitric oxide synthase inhibitor N-nitro-l-arginine methyl ester. AT1 receptor inhibition did not affect the response to ANG II, whereas AT2 receptor inhibition abolished the response in mitochondria from control rats and reversed the response to increased oxygen consumption through superoxide-induced mitochondrial uncoupling in mitochondria from diabetic rats. ANG II decrease mitochondrial respiration via AT2 receptor-mediated nitric oxide release in both control and diabetic rats. AT1 receptors do not regulate mitochondria function in control rats, whereas ANG II via AT1 receptors increase mitochondria leak respiration in diabetic animals.
|
|
| 22. |
|
|
| 23. |
- Friederich Persson, Malou, 1983-
(författare)
-
The Role of Mitochondrial Uncoupling in the Development of Diabetic Nephropathy
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes is closely associated with increased oxidative stress, especially originating from the mitochondria. A mechanism to reduce increased mitochondria superoxide production is to reduce the mitochondria membrane potential by releasing protons across the mitochondria membrane. This phenomenon is referred to as mitochondria uncoupling since oxygen is consumed independently of ATP being produced and can be mediated by Uncoupling Proteins (UCPs). However, increased oxygen consumption is potentially detrimental for the kidney since it can cause tissue hypoxia. Therefore, this thesis aimed to investigate the role of mitochondria uncoupling for development of diabetic nephropathy. UCP-2 was demonstrated to be the only isoform expressed in the kidney, and localized to tubular segments performing the majority of tubular electrolyte transport. Streptozotocin-induced diabetes in rats increased UCP-2 protein expression and correlated to increased non-transport dependent oxygen consumption in isolated proximal tubular cells. These effects were prevented by intense insulin treatment to the diabetic animals demonstrating a pivotal role of hyperglycemia. Importantly, elevated UCP-2 protein expression increased mitochondria uncoupling in mitochondria isolated from diabetic kidneys. Mitochondria uncoupling and altered morphology was also evident in kidneys from db/db-mice, a model of type-2 diabetes, together with proteinuria and glomerular hyperfiltration which are both clinical manifestations of diabetic nephropathy. Treatment with the antioxidant coenzyme Q10 prevented mitochondria uncoupling as well as morphological and functional alterations in these kidneys. Acute knockdown of UCP-2 paradoxically increased mitochondria uncoupling in a mechanism involving the adenosine nucleotide transporter. Increased uncoupling via adenosine nucleotide transporter decreased mitochondria membrane potential and kidney oxidative stress but did not affect glomerular filtration rate, renal blood flow, total kidney oxygen consumption or intrarenal tissue oxygen tension. The role of increased mitochondria oxygen consumption was investigated by administering the chemical uncoupler dinitrophenol to healthy rats. Importantly, increased mitochondria oxygen consumption resulted in kidney tissue hypoxia, proteinuria and increased staining of the tubular injury marker vimentin, demonstrating a crucial role of increased oxygen consumption per se and the resulting kidney tissue hypoxia for the development of nephropathy. Taken together, the data presented in this thesis establishes an important role of mitochondria uncoupling for the development of diabetic nephropathy.
|
|
| 24. |
- Kunath, Anne, et al.
(författare)
-
Inhibition of angiotensin-induced aortic aneurysm by metformin in apolipoprotein E-deficient mice
- 2021
-
Ingår i: JVS-Vascular Science. - Philadelphia, PA, United States : Elsevier. - 2666-3503. ; 2, s. 33-42
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Metformin is associated with a reduced incidence and growth of abdominal aortic aneurysms (AAAs). The aim of the present study was to investigate the inhibitory effects of metformin on AAA development and possible underlying mechanisms in experimentally induced AAAs in mice, along with the possible synergistic effects of metformin and imatinib.Methods: Angiotensin II was used to induce AAAs in apolipoprotein E knockout (ApoE -/- ) mice for 28 days. The mice were treated with metformin (n = 11), metformin combined with imatinib (n = 7), or vehicle (n = 12), starting 3 days before angiotensin II infusion. Ultrasound examination was used to analyze aneurysm formation. Cholesterol and blood pressure levels were measured at the start and end of the study. Gene array and quantitative polymerase chain reaction were used to analyze the changes in gene expression in the aorta. Wire myography was used to study vascular function.Results: Metformin (n = 11) suppressed the formation and progression of AAAs by 50% compared with the vehicle controls (n = 12), with no further effects from imatinib (n = 7). Metformin reduced total cholesterol and mRNA expression of SPP1 (encoding osteopontin), MMP12, and the glycoprotein genes Gpnmb and Clec7a. Furthermore, metformin inhibited blood pressure increases and reduced vascular contractions, as determined by wire myography, and restored the anticontractile function of perivascular adipose tissue.Conclusion: Metformin inhibited aneurysm formation and progression and normalized vascular function in ApoE -/- mice with no additional effect of imatinib. This might be mediated by the protective effects on vascular endothelial function and perivascular adipose tissue via reduced expression of genes promoting inflammation, including SPP1, MMP12, Gpnmb, and Clec7a.Clinical relevance: Retrospective studies of the effects of metformin in patients with aneurysm have so far only been performed of those with type 2 diabetes. The present study shows that metformin has effects on nondiabetic mice and revealed the mechanistic effects mediated by the drug that could also be important to study as outcomes in humans. Future clinical trials using metformin are warranted in patients without diabetes with abdominal aortic aneurysms.
|
|
| 25. |
- Lefranc, Clara, et al.
(författare)
-
Adipocyte-Mineralocorticoid Receptor Alters Mitochondrial Quality Control Leading to Mitochondrial Dysfunction and Senescence of Visceral Adipose Tissue
- 2021
-
Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:6
-
Tidskriftsartikel (refereegranskat)abstract
- Mineralocorticoid receptor (MR) expression is increased in the adipose tissue (AT) of obese patients and animals. We previously demonstrated that adipocyte-MR overexpression in mice (Adipo-MROE mice) is associated with metabolic alterations. Moreover, we showed that MR regulates mitochondrial dysfunction and cellular senescence in the visceral AT of obese db/db mice. Our hypothesis is that adipocyte-MR overactivation triggers mitochondrial dysfunction and cellular senescence, through increased mitochondrial oxidative stress (OS). Using the Adipo-MROE mice with conditional adipocyte-MR expression, we evaluated the specific effects of adipocyte-MR on global and mitochondrial OS, as well as on OS-induced damage. Mitochondrial function was assessed by high throughput respirometry. Molecular mechanisms were probed in AT focusing on mitochondrial quality control and senescence markers. Adipo-MROE mice exhibited increased mitochondrial OS and altered mitochondrial respiration, associated with reduced biogenesis and increased fission. This was associated with OS-induced DNA-damage and AT premature senescence. In conclusion, targeted adipocyte-MR overexpression leads to an imbalance in mitochondrial dynamics and regeneration, to mitochondrial dysfunction and to ageing in visceral AT. These data bring new insights into the MR-dependent AT dysfunction in obesity.
|
|
| 26. |
- Lefranc, Clara, et al.
(författare)
-
Mitochondrial oxidative stress in obesity : role of the mineralocorticoid receptor
- 2018
-
Ingår i: Journal of Endocrinology. - 0022-0795 .- 1479-6805. ; 238:3, s. R143-R159
-
Forskningsöversikt (refereegranskat)abstract
- Obesity is a multifaceted, chronic, low-grade inflammation disease characterized by excess accumulation of dysfunctional adipose tissue. It is often associated with the development of cardiovascular (CV) disorders, insulin resistance and diabetes. Under pathological conditions like in obesity, adipose tissue secretes bioactive molecules called 'adipokines', including cytokines, hormones and reactive oxygen species (ROS). There is evidence suggesting that oxidative stress, in particular, the ROS imbalance in adipose tissue, may be the mechanistic link between obesity and its associated CV and metabolic complications. Mitochondria in adipose tissue are an important source of ROS and their dysfunction contributes to the pathogenesis of obesity-related type 2 diabetes. Mitochondrial function is regulated by several factors in order to preserve mitochondria integrity and dynamics. Moreover, the renin-angiotensin-aldosterone system is over-activated in obesity. In this review, we focus on the pathophysiological role of the mineralocorticoid receptor in the adipose tissue and its contribution to obesity-associated metabolic and CV complications. More specifically, we discuss whether dysregulation of the mineralocorticoid system within the adipose tissue may be the upstream mechanism and one of the early events in the development of obesity, via induction of oxidative stress and mitochondrial dysfunction, thus impacting on systemic metabolism and the CV system.
|
|
| 27. |
- Lefranc, Clara, et al.
(författare)
-
MR (Mineralocorticoid Receptor) Induces Adipose Tissue Senescence and Mitochondrial Dysfunction Leading to Vascular Dysfunction in Obesity
- 2019
-
Ingår i: Hypertension. - : LIPPINCOTT WILLIAMS & WILKINS. - 0194-911X .- 1524-4563. ; 73:2, s. 458-468
-
Tidskriftsartikel (refereegranskat)abstract
- Adipose tissue (AT) senescence and mitochondrial dysfunction are associated with obesity. Studies in obese patients and animals demonstrate that the MR (mineralocorticoid receptor) contributes to obesity-associated cardiovascular complications through its specific role in AT. However, underlying mechanisms remain unclear. This study aims to elucidate whether MR regulates mitochondrial function in obesity, resulting in AT premature aging and vascular dysfunction. Obese (db/db) and lean (db/+) mice were treated with an MR antagonist or a specific mitochondria-targeted antioxidant. Mitochondrial and vascular functions were determined by respirometry and myography, respectively. Molecular mechanisms were probed by Western immunoblotting and real-time polymerase chain reaction in visceral AT and arteries and focused on senescence markers and redox-sensitive pathways. db/db mice displayed AT senescence with activation of the p53-p21 pathway and decreased SIRT (sirtuin) levels, as well as mitochondrial dysfunction. Furthermore, the beneficial anticontractile effects of perivascular AT were lost in db/db via ROCK (Rho kinase) activation. MR blockade prevented these effects. Thus, MR activation in obesity induces mitochondrial dysfunction and AT senescence and dysfunction, which consequently increases vascular contractility. In conclusion, our study identifies novel mechanistic insights involving MR, adipose mitochondria, and vascular function that may be of importance to develop new therapeutic strategies to limit obesity-associated cardiovascular complications.
|
|
| 28. |
- Lindahl, Emma, et al.
(författare)
-
Early transcriptional regulation by C-peptide in freshly isolated rat proximal tubular cells
- 2011
-
Ingår i: Diabetes/Metabolism Research Reviews. - : Wiley. - 1520-7552 .- 1520-7560. ; 27:7, s. 697-704
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Clinical studies have shown that proinsulin C-peptide exerts renoprotective effects in type 1 diabetes, although the underlying mechanisms are poorly understood. As C-peptide has been shown to induce several intracellular events and to localize to nuclei, we aimed to determine whether gene transcription is affected in proximal tubular kidney cells, and if so, whether genes with altered transcription include those related to protective mechanisms. METHODS: The effect of C-peptide incubation (2h) on gene expression was investigated in freshly isolated proximal tubular cells from streptozotocin-diabetic Sprague-Dawley rats using global gene expression profiling and RT-qPCR. Protein expression was assayed using western blotting. Different bioinformatic strategies were employed. RESULTS: Gene transcription profiling demonstrated differential transcription of 492 genes (p<0.01) after 2h of C-peptide exposure, with the majority of these genes repressed (83%). RT-qPCR validation supported a trend of several GPCR's being activated, and certain transcription factors to be repressed. Also, C-peptide repressed the transcription of genes associated with pathways of circulatory and inflammatory diseases. CONCLUSIONS: This study shows that C-peptide exerts early effects on gene transcription in proximal tubular cells. The findings also bring further knowledge to the renoprotective mechanisms of C-peptide in type I diabetes, and supports a transcriptional activity for C-peptide. It is suggested that C-peptide may play a regulatory role in the gene expression of proximal tubular cells.
|
|
| 29. |
- Nordquist, Lina, et al.
(författare)
-
Activation of Hypoxia-Inducible Factors Prevents Diabetic Nephropathy
- 2015
-
Ingår i: Journal of the American Society of Nephrology. - : American Society of Nephrology. - 1046-6673 .- 1533-3450. ; 26:2, s. 328-338
-
Tidskriftsartikel (refereegranskat)abstract
- Hyperglycemia results in increased oxygen consumption and decreased oxygen tension in the kidney. We tested the hypothesis that activation of hypoxia-inducible factors (HIFs) protects against diabetes-induced alterations in oxygen metabolism and kidney function. Experimental groups consisted of control and streptozotocin-induced diabetic rats treated with or without chronic cobalt chloride to activate HIFs. We elucidated the involvement of oxidative stress by studying the effects of acute administration of the superoxide dismutase mimetic tempol. Compared with controls, diabetic rats displayed tissue hypoxia throughout the kidney, glonnerular hyperfiltration, increased oxygen consumption, increased total mitochondrial leak respiration, and decreased tubular sodium transport efficiency. Diabetic kidneys showed proteinuria and tubulointerstitial damage. Cobalt chloride activated HIFs, prevented the diabetes-induced alterations in oxygen metabolism, mitochondrial leak respiration, and kidney function, and reduced proteinuria and tubulointerstitial damage. The beneficial effects of tempol were less pronounced after activation of HIFs, indicating improved oxidative stress status. In conclusion, activation of HIFs prevents diabetes-induced alteration in kidney oxygen metabolism by normalizing glomerular filtration, which reduces tubular electrolyte load, preventing mitochondrial leak respiration and improving tubular transport efficiency. These improvements could be related to reduced oxidative stress and account for the reduced proteinuria and tubulointerstitial damage. Thus, pharnnacologic activation of the HIF system may prevent development of diabetic nephropathy.
|
|
| 30. |
- Palm, Fredrik, et al.
(författare)
-
Reduced nitric oxide in diabetic kidneys due to increased hepatic arginine metabolism : implications for renomedullary oxygen availability
- 2008
-
Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 0363-6127 .- 1522-1466 .- 1931-857X. ; 294:1, s. F30-7
-
Tidskriftsartikel (refereegranskat)abstract
- Nitric oxide (NO) is a potent regulator of both vascular tone and oxygen utilization. Diabetes is commonly associated with both NO deficiency and reduced renomedullary oxygen availability. Arginine availability as regulator of NO production has gained growing interest. We hypothesized that arginine limitation causes diabetes-induced renomedullary NO deficiency, which directly influences renomedullary oxygen tension (P(o2)). Medullary NO, P(o2), and blood flow were measured in control and streptozotocin-induced diabetic rats, which were treated or not treated with alpha-tocopherol, and administered l-arginine followed by N(omega)-nitro-l-arginine methyl ester. Major components of arginine metabolism were also investigated. Diabetic rats had reduced renomedullary NO levels compared with controls. Arginine selectively increased NO levels in diabetic rats and totally restored NO levels in alpha-tocopherol-treated animals. Tocopherol prevented the reduction in medullary P(o2) in the diabetic animals. Although blood flow increased equally in all groups, arginine increased P(o2) exclusively in the diabetic groups. Diabetes decreased plasma arginine and asymmetric dimethylarginine concentrations, but increased hepatic CAT-2A and plasma ornithine independently of alpha-tocopherol treatment. In conclusion, diabetic rats had reduced renomedullary NO due to decreased plasma arginine following increased hepatic arginine uptake and degradation. This was unrelated to oxidative stress. The diabetes-induced reduction in renomedullary P(o2) was restored by either acute arginine administration, which also restored NO levels, or long-term antioxidant treatment. Arginine increased medullary NO and P(o2) independently of altered hemodynamics in the diabetic groups. This reveals a direct regulatory function of NO for renomedullary P(o2) especially during situations of elevated oxidative stress.
|
|
| 31. |
|
|
| 32. |
- Papazova, Diana A., et al.
(författare)
-
Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension
- 2015
-
Ingår i: American Journal of Physiology - Renal Physiology. - : American Physiological Society. - 0363-6127 .- 1522-1466 .- 1931-857X. ; 308:1, s. F22-F28
-
Tidskriftsartikel (refereegranskat)abstract
- Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (PO2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney hypoxia. Lewis rats underwent syngenic renal transplantation (TX) and contralateral nephrectomy. Controls were uninephrectomized (1K-CON) or left untreated (2K-CON). After 7 days, urinary excretion of protein and thiobarbituric acid-reactive substances were measured, and after 14 days glomerular filtration rate (GFR), renal blood flow, whole kidney QO(2), cortical PO2, kidney cortex mitochondrial uncoupling, renal oxidative damage, and tubulointerstitial injury were assessed. TX, compared with 1K-CON, resulted in mitochondrial uncoupling mediated via uncoupling protein-2 (16 +/- 3.3 vs. 0.9 +/- 0.4 pmol O-2.s(-1) .mg protein(-1), P < 0.05) and increased whole kidney Q(O2) (55 +/- 16 vs. 33 +/- 10 mu mol O-2/min, P < 0.05). Corticomedullary P-O2 was lower in TX compared with 1K-CON (30 +/- 13 vs. 47 +/- 4 mu M, P < 0.05) whereas no significant difference was observed between 2K-CON and 1K-CON rats. Proteinuria, oxidative damage, and the tubulointerstitial injury score were not significantly different in 1K-CON and TX. Treatment of donors for 5 days with mito-TEMPO reduced mitochondrial uncoupling but did not affect renal hemodynamics, Q(O2), P-O2, or injury. Collectively, our results demonstrate increased mitochondrial uncoupling as an early event after experimental renal transplantation associated with increased oxygen consumption and kidney hypoxia in the absence of increases in markers of damage.
|
|
| 33. |
- Patinha, Daniela, et al.
(författare)
-
Determinants of renal oxygen metabolism during low Na+ diet : effect of angiotensin II AT1 and aldosterone receptor blockade
- 2020
-
Ingår i: Journal of Physiology. - 0022-3751 .- 1469-7793. ; 598:23, s. 5573-5587
-
Tidskriftsartikel (refereegranskat)abstract
- Reducing Na(+)intake reduces the partial pressure of oxygen in the renal cortex and activates the renin-angiotensin-aldosterone system. In the absence of high blood pressure, these consequences of dietary Na(+)reduction may be detrimental for the kidney. In a normotensive animal experimental model, reducing Na(+)intake for 2 weeks increased renal oxygen consumption, which was normalized by mineralocorticoid receptor blockade. Furthermore, blockade of the angiotensin II AT(1)receptor restored cortical partial pressure of oxygen by improving oxygen delivery. This shows that increased activity of the renin-angiotensin-aldosterone system contributes to increased oxygen metabolism in the kidney after 2 weeks of a low Na(+)diet. The results provide insights into dietary Na(+)restriction in the absence of high blood pressure, and its consequences for the kidney. Reduced Na(+)intake reduces thePO2(partial pressure of oxygen) in the renal cortex. Upon reduced Na(+)intake, reabsorption along the nephron is adjusted with activation of the renin-angiotensin-aldosterone system (RAAS). Thus, we studied the effect of reduced Na(+)intake on renal oxygen homeostasis and function in rats, and the impact of intrarenal angiotensin II AT(1)receptor blockade using candesartan and mineralocorticoid receptor blockade using canrenoic acid potassium salt (CAP). Male Sprague-Dawley rats were fed standard rat chow containing normal (0.25%) and low (0.025%) Na(+)for 2 weeks. The animals were anaesthetized (thiobutabarbital 120 mg kg(-1)) and surgically prepared for kidney oxygen metabolism and function studies before and after acute intrarenal arterial infusion of candesartan (4.2 mu g kg(-1)) or intravenous infusion of CAP (20 mg kg(-1)). Baseline mean arterial pressure and renal blood flow were similar in both dietary groups. Fractional Na(+)excretion and cortical oxygen tension were lower and renal oxygen consumption was higher in low Na(+)groups. Neither candesartan nor CAP affected arterial pressure. Renal blood flow and cortical oxygen tension increased in both groups after candesartan in the low Na(+)group. Fractional Na(+)excretion was increased and oxygen consumption reduced in the low Na(+)group after CAP. These results suggest that blockade of angiotensin II AT(1)receptors has a major impact upon oxygen delivery during normal and low Na(+)conditions, while aldosterone receptors mainly affect oxygen metabolism following 2 weeks of a low Na(+)diet.
|
|
| 34. |
- Persson, Malou Friederich, et al.
(författare)
-
Kidney function after in vivo gene silencing of Uncoupling Protein-2 in streptozotocin-induced diabetic rats
- 2013
-
Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer-Verlag New York. - 0065-2598 .- 2214-8019. - 9781461447719 - 9781461449898 ; 765, s. 217-223
-
Tidskriftsartikel (refereegranskat)abstract
- Kidney uncoupling protein 2 (UCP-2) increases in streptozotocin-induced diabetes, resulting in mitochondria uncoupling, i.e., increased oxygen consumption unrelated to active transport. The present study aimed to investigate the role of UCP-2 for normal and diabetic kidney function utilizing small interference RNA (siRNA) to reduce protein expression. Diabetic animals had increased glomerular filtration rate and kidney oxygen consumption, resulting in decreased oxygen tension and transported sodium per consumed oxygen. UCP-2 protein levels decreased 2 and 50% after UCP-2 siRNA administration in control and diabetic animals respectively. Kidney function was unaffected by in vivo siRNA-mediated gene silencing of UCP-2. The reason for the lack of effect of reducing UCP-2 is presently unknown but may involve compensatory mitochondrial uncoupling by the adenosine nucleotide transporter.
|
|
| 35. |
- Persson, Patrik, et al.
(författare)
-
Adenosine A(2)a receptor stimulation prevents proteinuria in diabetic rats by promoting an anti-inflammatory phenotype without affecting oxidative stress
- 2015
-
Ingår i: Acta Physiologica. - : Wiley: 12 months. - 1748-1708 .- 1748-1716. ; 214:3, s. 311-318
-
Tidskriftsartikel (refereegranskat)abstract
- AimDiabetic patients are at increased risk for kidney disease. There is presently no clinical treatment available that effectively protects kidney function in diabetics. This study investigates whether chronic stimulation of the adenosine A(2a) receptor (A(2a)AR) protects kidney function in insulinopenic diabetic rats. MethodsStreptozotocin-induced diabetic rats and corresponding controls were chronically treated with the adenosine A(2a)AR agonist CGS21680 throughout the four-week diabetes duration. Kidney function was thereafter investigated, and urine and plasma samples were collected for analysis of protein, oxidative stress and inflammatory markers. ResultsGlomerular filtration rate, renal blood flow, filtration fraction and diabetes-induced kidney hypoxia were all unaffected by chronic A(2a)AR stimulation. Furthermore, diabetic rats had increased oxidative stress, which was further increased by chronic A(2a)AR stimulation. However, the 10-fold increased urinary protein excretion observed in the diabetic rats was completely prevented by chronic A(2a)AR stimulation. These beneficial effects were accompanied by reduced levels of the pro-inflammatory TNF- and increased levels of the anti-inflammatory IL-10 as well as decreased infiltration of macrophages, glomerular damage and basement membrane thickness. ConclusionChronic A(2a)AR stimulation prevents proteinuria and glomerular damage in experimental diabetes via an anti-inflammatory mechanism independent of oxidative stress and kidney hypoxia.
|
|
| 36. |
- Persson, Patrik, et al.
(författare)
-
Browning of perivascular adipose tissue prevents vascular dysfunction and reduces hypertension in angiotensin II-infused mice
- 2023
-
Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 325:3, s. R290-R298
-
Tidskriftsartikel (refereegranskat)abstract
- Hypertension is a world-leading cause of cardiovascular disease and premature deaths. Vascular tone is in part regulated by perivascular adipose tissue (PVAT) that releases pro and anticontractile factors. In hypertension, dysfunctional PVAT is observed and studies have indicated a causal relationship between dysfunctional PVAT and vascular damage in hypertension. The phenotype of PVAT on resistance vessels is primarily white adipose tissue. The present study investigates the impact of a changed phenotype, i.e., browning of PVAT, on vascular function and the development of hypertension. Browning was induced by β3-adrenergic agonist in control and angiotensin II-induced hypertensive mice. Studied parameters included blood pressure by tail-cuff plethysmography and vascular function by wire myography. Browning was confirmed through an immunohistochemical and gene analysis approach. The anticontractile effect of PVAT is lost in untreated hypertensive mice and vascular tone and blood pressure are increased. Browning of PVAT resulted in a maintained anticontractile effect, improved endothelial function, and reduced development of hypertension. Phenotype of PVAT is a major determinant of PVAT health during hypertensive conditions. Our data clearly demonstrates that browning of PVAT, i.e. changing the phenotype of PVAT, protects the vascular function and counteract the development of hypertension. This study provides novel insights into how PVAT can be protected in pathologies and thus limit the development of hypertension.
|
|
| 37. |
- Schiffer, Tomas A., et al.
(författare)
-
Mitochondrial Reactive Oxygen Species and Kidney Hypoxia in the Development of Diabetic Nephropathy
- 2017
-
Ingår i: Frontiers in Physiology. - : FRONTIERS MEDIA SA. - 1664-042X. ; 8
-
Forskningsöversikt (refereegranskat)abstract
- The underlying mechanisms in the development of diabetic nephropathy are currently unclear and likely consist of a series of dynamic events from the early to late stages of the disease. Diabetic nephropathy is currently without curative treatments and it is acknowledged that even the earliest clinical manifestation of nephropathy is preceded by an established morphological renal injury that is in turn preceded by functional and metabolic alterations. An early manifestation of the diabetic kidney is the development of kidney hypoxia that has been acknowledged as a common pathway to nephropathy. There have been reports of altered mitochondrial function in the diabetic kidney such as altered mitophagy, mitochondrial dynamics, uncoupling, and cellular signaling through hypoxia inducible factors and AMP-kinase. These factors are also likely to be intertwined in a complex manner. In this review, we discuss how these pathways are connected to mitochondrial production of reactive oxygen species (ROS) and how they may relate to the development of kidney hypoxia in diabetic nephropathy. From available literature, it is evident that early correction and/or prevention of mitochondrial dysfunction may be pivotal in the prevention and treatment of diabetic nephropathy.
|
|
| 38. |
- Sivertsson, Ebba, et al.
(författare)
-
Dose-dependent angiotensin II regulation of mitochondrial function – involvement of Uncoupling protein and Adenine nucleotide translocator
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Increased angiotensin II (Ang II) signaling has been implicated in several conditions associated with the development of chronic kidney disease, including hypertension and diabetes. Increased mitochondrial leak respiration has been shown to be a contributing factor to development of intrarenal hypoxia, a unifying mechanism for chronic kidney disease. However, the link between increased Ang II signaling and renal mitochondrial leak respiration is less clear. We therefore investigated how increased Ang II signaling affects leak respiration of kidney cortex mitochondria by focusing on the two main components of regulated leak respiration, i.e. uncoupling protein 2 (UCP2) and adenine nucleotide translocator (ANT).Wild-type and UCP2 deficient mice were randomly assigned to receive either vehicle or Ang II in low dose (400 ng/kg/min) or high dose (1000 ng/kg/min) for 4 weeks via osmotic minipumps. Thereafter, mitochondria function was measured by high resolution respirometry and gene expressions of the different UCP isoforms, superoxide dismutase (SOD) 1-3 and angiotensin receptor isoforms were measured by quantitative real time PCR. Thiobarbituric acids reactive substances (TBARS) was determined in kidney cortex as a marker of oxidative stress status.Low dose Ang II increased overall mitochondria respiration, but only improved respiratory control ratio in UCP2 deficient animals. However, high dose Ang II decreased overall mitochondria respiration, as a result of reduced mitochondrial efficiency for ATP production, independently of genotype. These effects were accompanied by alterations in regulated mitochondrial leak respiration and correlated to oxidative stress status.In conclusion, Ang II dose-dependently effects mitochondrial function and leak respiration. When intact, both ANT- and UCP2-dependent pathways maintain mitochondrial function during moderate Ang II signaling, whereas during high Ang II signaling overall mitochondrial function is compromised independently of ANT- or UCP2-mediated pathways.
|
|
| 39. |
- Sivertsson, Ebba, et al.
(författare)
-
Dose-dependent regulation of kidney mitochondrial function by angiotensin II
- 2023
-
Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 128:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Intrarenal hypoxia has been suggested a unifying pathway to chronic kidney disease (CKD) and increased mitochondria leak respiration, which increases mitochondrial oxygen usage and is one important mechanism contributing to the development of the hypoxia. Previous studies indicate that angiotensin II (Ang II) effects on mitochondria function could be dose dependent. We investigated how moderate and high levels of Ang II affect kidney mitochondria function and pathways of leak respiration. Methods: C57 black 6 mice were treated with either vehicle or Ang II in low dose (400 ng/kg/min) or high dose (1,000 ng/kg/min) for 4 weeks. The function of kidney cortex mitochondria was measured by high-resolution respirometry. Ang II effects on gene expression in kidney tissue were measured by quantitative real-time PCR. Thiobarbituric acids reactive substances were determined as a marker of oxidative stress, and urinary protein excretion was measured as a maker of kidney injury. Results: Low-dose Ang II induced overall mitochondria respiration, without compromising capacity of ATP production. Mitochondrial leak respiration was increased, and levels of oxidative stress were unchanged. However, high-dose Ang II decreased overall mitochondria respiration and reduced mitochondrial capacity for ATP production. Mitochondrial leak respiration was decreased, and oxidative stress increased in kidney tissue. Furthermore, gene expression of mediators that stimulate vasoconstriction and ROS production was increased, while components of counteracting pathways were decreased. Conclusions: In conclusion, Ang II dose-dependently affects mitochondrial function and leak respiration. Thus, Ang II has the potential to directly affect cellular metabolism during conditions of altered Ang II signaling.
|
|
| 40. |
- Sivertsson, Ebba, et al.
(författare)
-
Inhibition of mammalian target of rapamycin decreases intrarenal oxygen availability and alters glomerular permeability
- 2018
-
Ingår i: American Journal of Physiology - Renal Physiology. - : AMER PHYSIOLOGICAL SOC. - 1931-857X .- 1522-1466. ; 314:5, s. F864-F872
-
Tidskriftsartikel (refereegranskat)abstract
- An increased kidney oxygen consumption causing tissue hypoxia has been suggested to be a common pathway toward chronic kidney disease. The mammalian target of rapamycin (mTOR) regulates cell proliferation and mitochondrial function. mTOR inhibitors (e.g., rapamycin) are used clinically to prevent graft rejection. mTOR has been identified as a key player in diabetes, which has stimulated the use of mTOR inhibitors to counter diabetic nephropathy. However, the effect of mTOR inhibition on kidney oxygen consumption is unknown. Therefore, we investigated the effects of mTOR inhibition on in vivo kidney function, oxygen homeostasis, and glomerular permeability. Control and streptozotocin-induced diabetic rats were chronically treated with rapamycin, and the functional consequences were studied 14 days thereafter. In both groups, mTOR inhibition induced mitochondrial uncoupling, resulting in increased total kidney oxygen consumption and decreased intrarenal oxygen availability. Concomitantly, mTOR inhibition induced tubular injury, as estimated from urinary excretion of kidney injury molecule-1 (KIM-1) and reduced urinary protein excretion. The latter corresponded to reduced sieving coefficient for large molecules. In conclusion, mTOR inhibition induces mitochondrial dysfunction leading to decreased oxygen availability in normal and diabetic kidneys. which translates into increased KIM-1 in the urine. Reduced proteinuria after mTOR inhibition is an effect of reduced glomerular permeability for large molecules. Since hypoxia has been suggested as a common pathway in the development of chronic kidney disease, mTOR inhibition to patients with preexisting nephropathy should be used with caution, since it may accelerate the progression of the disease.
|
|
| 41. |
- Sivertsson, Ebba, et al.
(författare)
-
Inhibition of Mammalian Target of Rapamycin Induces Renal Mitochondrial Uncoupling in Rats
- 2013
-
Ingår i: Oxygen Transport To Tissue XXXV. - New York, NY : Springer New York. - 9781461474111 - 9781461472568 ; , s. 309-314
-
Konferensbidrag (refereegranskat)abstract
- The mechanisms underlying diabetic nephropathy are not fully understood. However, recent research indicates mitochondria dysfunction as a contributing factor. Mammalian target of rapamycin (mTOR) is a known regulator of mitochondria function and could therefore also be involved in the development of diabetic nephropathy. The present study investigates the role of mTOR for controlling the function of mitochondria isolated from normal and diabetic rat kidneys. Control and streptozotocin-induced diabetic rats were treated with the mTOR inhibitor rapamycin (0.2 mg/day) by oral gavage for 14 days, after which mitochondria function was investigated using high-resolution respirometry. Mitochondrial uncoupling was defined as increased oxygen usage unrelated to ATP production. mTOR inhibition induced mitochondria uncoupling in control rats, but did not affect the already occurring uncoupling in kidney mitochondria from diabetic animals. Inhibition of mTOR using rapamycin induces mitochondria uncoupling in control rats, suggesting a role of mTOR as a moderator of mitochondria efficiency. No effect of mTOR inhibition was observed in mitochondria from diabetic animals, suggesting that there are other pathways in addition to the mTOR pathway regulating mitochondria function in diabetes. The functional significance of the mTOR pathway in regulating mitochondria efficiency warrants further attention.
|
|
| 42. |
- Sivertsson, Ebba, 1984-, et al.
(författare)
-
Thyroid hormone increases oxygen metabolism causing intrarenal tissue hypoxia; a pathway to kidney disease
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The proposed mechanisms for the development of nephropathy are many, complex and often overlapping. Although recent literature strongly supports a role of kidney hypoxia as an independent pathway to nephropathy, the evidence remains inconclusive since the role of hypoxia is difficult to differentiate from confounding factors such as hyperglycemia, hypertension and oxidative stress. By increasing kidney oxygen consumption using triiodothyronine (T3) and, thus, avoiding these confounding factors, the aim of the present study was to investigate renal hypoxia per se as a causal pathway for the development of nephropathy.Healthy Sprague-Dawley rats were treated with T3 (10 µg/kg/day) and the angiotensin II AT1-receptor antagonist candesartan (1 mg/kg in drinking water) to eliminate effects of T3-induced renin release for 7 weeks after which in vivo kidney function, oxygen metabolism and mitochondrial function were evaluated.T3 did not affect glomerular filtration rate or renal blood flow, but increased total kidney oxygen consumption resulting in cortical hypoxia. Nephropathy, demonstrated as proteinuria and albuminuria developed in T3-treated animals. Mitochondria uncoupling mediated by uncoupling protein 2 and the adenosine nucleotide transporter was demonstrated as a mechanism causing the increased kidney oxygen consumption. Importantly, blood glucose levels, mean arterial blood pressure and oxidative stress levels were not affected by T3. In conclusion, the present study provides further evidence for increased kidney oxygen consumption causing intrarenal tissue hypoxia, as a causal pathway for development of nephropathy.
|
|
| 43. |
- Sivertsson, Ebba, et al.
(författare)
-
Thyroid hormone increases oxygen metabolism causing intrarenal tissue hypoxia; a pathway to kidney disease
- 2022
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:3
-
Tidskriftsartikel (refereegranskat)abstract
- The proposed mechanisms for the development of nephropathy are many, complex and often overlapping. Although recent literature strongly supports a role of kidney hypoxia as an independent pathway to nephropathy, the evidence remains inconclusive since the role of hypoxia is difficult to differentiate from confounding factors such as hyperglycemia, hypertension and oxidative stress. By increasing kidney oxygen consumption using triiodothyronine (T-3) and, thus, avoiding these confounding factors, the aim of the present study was to investigate renal hypoxia per se as a causal pathway for the development of nephropathy. Healthy Sprague-Dawley rats were treated with T-3 (10 mu g/kg/day) and the angiotensin II AT(1)-receptor antagonist candesartan (1 mg/kg in drinking water) to eliminate effects of T-3-induced renin release; and compared to a candesartan treated control group. After 7 weeks of treatment in vivo kidney function, oxygen metabolism and mitochondrial function were evaluated. T-3 did not affect glomerular filtration rate or renal blood flow, but increased total kidney oxygen consumption resulting in cortical hypoxia. Nephropathy, demonstrated as albuminuria and tubulointerstitial fibrosis, developed in T-3-treated animals. Mitochondria uncoupling mediated by uncoupling protein 2 and the adenosine nucleotide transporter was demonstrated as a mechanism causing the increased kidney oxygen consumption. Importantly, blood glucose levels, mean arterial blood pressure and oxidative stress levels were not affected by T-3. In conclusion, the present study provides further evidence for increased kidney oxygen consumption causing intrarenal tissue hypoxia, as a causal pathway for development of nephropathy.
|
|
| 44. |
- Stridh, Sara, 1983-, et al.
(författare)
-
Hyaluronan Production by Renomedullary Interstitial Cells : Influence of Endothelin, Angiotensin II and Vasopressin
- 2017
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 18:12
-
Tidskriftsartikel (refereegranskat)abstract
- The content of hyaluronan (HA) in the interstitium of the renal medulla changes in relation to body hydration status. We investigated if hormones of central importance for body fluid homeostasis affect HA production by renomedullary interstitial cells in culture (RMICs). Simultaneous treatment with vasopressin and angiotensin II (Ang II) reduced HA by 69%. No change occurred in the mRNA expressions of hyaluronan synthase 2 (HAS2) or hyaluronidases (Hyals), while Hyal activity in the supernatant increased by 67% and CD44 expression reduced by 42%. The autocoid endothelin (ET-1) at low concentrations (10-10 and 10-8 M) increased HA 3-fold. On the contrary, at a high concentration (10-6 M) ET-1 reduced HA by 47%. The ET-A receptor antagonist BQ123 not only reversed the reducing effect of high ET-1 on HA, but elevated it to the same level as low concentration ET-1, suggesting separate regulating roles for ET-A and ET-B receptors. This was corroborated by the addition of ET-B receptor antagonist BQ788 to low concentration ET-1, which abolished the HA increase. HAS2 and Hyal2 mRNA did not alter, while Hyal1 mRNA was increased at all ET-1 concentrations tested. Hyal activity was elevated the most by high ET-1 concentration, and blockade of ET-A receptors by BQ123 prevented about 30% of this response. The present study demonstrates an important regulatory influence of hormones involved in body fluid balance on HA handling by RMICs, thereby supporting the concept of a dynamic involvement of interstitial HA in renal fluid handling.
|
|
| 45. |
|
|
