| 1. |
- Brown, Jenifer M., et al.
(författare)
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Cardiac Structure and Function Across the Spectrum of Aldosteronism: the Atherosclerosis Risk in Communities Study
- 2022
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Ingår i: Hypertension. - : LIPPINCOTT WILLIAMS & WILKINS. - 0194-911X .- 1524-4563. ; 79:9, s. 1984-1993
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Tidskriftsartikel (refereegranskat)abstract
- Background: Aldosterone production and mineralocorticoid receptor activation are implicated in myocardial fibrosis and cardiovascular events. Methods: Cardiac structure and function were assessed in 4547 participants without prevalent heart failure (HF) in the ARIC study (Atherosclerosis Risk in Communities), with echocardiography, aldosterone, and plasma renin activity measurement (2011-2013). Subjects were characterized by plasma renin activity as suppressed (<= 0.5 ng/mL per hour) or unsuppressed (>0.5 ng/mL per hour). Cross-sectional relationships with cardiac structure and function, and longitudinal relationships with outcomes (HF hospitalization; HF and all-cause death; HF, death, myocardial infarction, and stroke; and incident atrial fibrillation) were assessed. Models were adjusted for demographic and anthropometric characteristics and additively, for blood pressure and antihypertensives. Results: Evidence of primary aldosteronism physiology was prevalent (11.6% with positive screen) and associated with echocardiographic parameters. Renin suppression was associated with greater left ventricular mass, left ventricular volumes, and left atrial volume index, and a lower E/A ratio (adjusted P<0.001 for all). Higher aldosterone was associated with greater left ventricular mass and lower global longitudinal strain and lateral E . The highest tertile of aldosterone was associated with a hazard ratio of 1.37 (95% CI, 1.06-1.77; 5.5-year follow-up) for incident atrial fibrillation relative to the lowest. Renin suppression was associated with HF (hazard ratio, 1.34 [95% CI, 1.05-1.72]; 7.3-year follow-up), although these relationships did not remain statistically significant after additional adjustment for hypertension. Conclusions: Renin suppression and aldosterone excess, consistent with primary aldosteronism pathophysiology, were associated with cardiac structural and functional alterations and may represent an early target for mitigation of fibrosis with mineralocorticoid receptor antagonists.
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| 2. |
- Friederich-Persson, Malou, et al.
(författare)
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Kidney Hypoxia, Attributable to Increased Oxygen Consumption, Induces Nephropathy Independently of Hyperglycemia and Oxidative Stress
- 2013
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Ingår i: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 62:5, s. 914-919
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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.
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| 3. |
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| 4. |
- Palm, Fredrik, et al.
(författare)
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Angiotensin II Type 2 Receptors and Nitric Oxide Sustain Oxygenation in the Clipped Kidney of Early Goldblatt Hypertensive Rats
- 2008
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 51:2, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- Angiotensin-converting enzyme inhibitors (ACEIs) decrease the glomerular filtration rate and renal blood flow in the clipped kidneys of early 2-kidney, 1-clip Goldblatt hypertensive rats, but the consequences for oxygenation are unclear. We investigated the hypothesis that angiotensin II type 1 or angiotensin II type 2 receptors or NO synthase mediate renal oxygenation responses to ACEI. Three weeks after left renal artery clipping, kidney function, oxygen (O2) use, renal blood flow, renal cortical blood flow, and renal cortical oxygen tension (PO2) were measured after acute administration of an ACEI (enalaprilat) and after acute administration of ACEI following acute administration of an angiotensin II type 1 or angiotensin II type 2 receptor blocker (candesartan or PD-123,319) or an NO synthase blocker (NG-nitro-L-arginine methyl ester with control of renal perfusion pressure) and compared with mechanical reduction in renal perfusion pressure to the levels after ACEI. The basal renal cortical PO2 of clipped kidneys was significantly lower than contralateral kidneys (35±1 versus 51±1 mm Hg; n=40 each). ACEI lowered renal venous PO2, cortical PO2, renal blood flow, glomerular filtration rate, and cortical blood flow and increased the renal vascular resistance in the clipped kidney, whereas mechanical reduction in renal perfusion pressure was ineffective. PD-123,319 and NG-nitro-L-arginine methyl ester, but not candesartan, reduced the PO2 of clipped kidneys and blocked the fall in PO2 with acute ACEI administration. In conclusion, oxygen availability in the clipped kidney is maintained by angiotensin II generation, angiotensin II type 2 receptors, and NO synthase. This discloses a novel mechanism whereby angiotensin can prevent hypoxia in a kidney challenged with a reduced perfusion pressure.
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| 5. |
- Palm, Fredrik, et al.
(författare)
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Blood pressure, blood flow, and oxygenation in the clipped kidney of chronic 2-kidney, 1-clip rats : effects of tempol and Angiotensin blockade
- 2010
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 55:2, s. 298-304
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Tidskriftsartikel (refereegranskat)abstract
- Angiotensin II maintains renal cortical blood flow and renal oxygenation in the clipped kidney of early 2-kidney, 1-clip Goldblatt hypertensive (2K,1C) rats. The involvement of Ang II is believed to decline, whereas oxidative stress increases during the progression of 2K,1C hypertension. We investigated the hypothesis that the acute administration of drugs to inhibit reactive oxygen species (Tempol), angiotensin II type 1 receptors (candesartan), or angiotensin-converting enzyme (enalaprilat) lowers mean arterial pressure and increases kidney blood flow and oxygenation in the clipped kidney of chronic 2K,1C rats in contrast to sham controls. Twelve months after left renal artery clipping or sham, mean arterial pressure, renal cortical blood flow, and renal cortical and medullary oxygen tension were measured after acute administration of Tempol followed by enalaprilat or candesartan followed by enalaprilat. The mean arterial pressure of the 2K,1C rat was reduced by candesartan (-9%) and, more effectively, by Tempol (-35%). All of the applied treatments had similar blood pressure-lowering effects in sham rats (average: -21%). Only Tempol increased cortical blood flow (+35%) and cortical and medullary oxygen tensions (+17% and +94%, respectively) in clipped kidneys of 2K,1C rats. Administration of enalaprilat had no additional effect, except for a modest reduction in cortical blood flow in the clipped kidney of 2K,1C rats when coadministered with candesartan (-10%). In conclusion, acute administration of Tempol is more effective than candesartan in reducing the mean arterial blood pressure and improving renal blood perfusion and oxygenation in the clipped kidney of chronic 2K,1C rats.
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| 6. |
- Persson, Patrik, et al.
(författare)
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L-Citrulline, But Not L-Arginine, Prevents Diabetes Mellitus–Induced Glomerular Hyperfiltration and Proteinuria in Rat
- 2014
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Ingår i: Hypertension. - : Lippincott Williams & Wilkins. - 0194-911X .- 1524-4563. ; 64:2, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- Diabetes mellitus–induced oxidative stress causes increased renal oxygen consumption and intrarenal tissue hypoxia. Nitric oxide is an important determinant of renal oxygen consumption and electrolyte transport efficiency. The present study investigates whether l-arginine or l-citrulline to promote nitric oxide production prevents the diabetes mellitus–induced kidney dysfunction. Glomerular filtration rate, renal blood flow, in vivo oxygen consumption, tissue oxygen tension, and proteinuria were investigated in control and streptozotocin-diabetic rats with and without chronic l-arginine or l-citrulline treatment for 3 weeks. Untreated and l-arginine–treated diabetic rats displayed increased glomerular filtration rate (2600±162 versus 1599±127 and 2290±171 versus 1739±138 µL/min per kidney), whereas l-citrulline prevented the increase (1227±126 versus 1375±88 µL/min per kidney). Filtration fraction was increased in untreated diabetic rats because of the increase in glomerular filtration rate but not in l-arginine– or l-citrulline–treated diabetic rats. Urinary protein excretion was increased in untreated and l-arginine–treated diabetic rats (142±25 versus 75±7 and 128±7 versus 89±7 µg/min per kidney) but not in diabetic rats administered l-citrulline (67±7 versus 61±5 µg/min per kidney). The diabetes mellitus–induced tissue hypoxia, because of elevated oxygen consumption, was unaltered by any of the treatments. l-citrulline administered to diabetic rats increases plasma l-arginine concentration, which prevents the diabetes mellitus–induced glomerular hyperfiltration, filtration fraction, and proteinuria, possibly by a vascular effect.
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