| 1. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Growth hormone-induced blood pressure decrease is associated with increased mRNA levels of the vascular smooth muscle KATP channel.
- 2004
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Ingår i: The Journal of endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 183:1, s. 195-202
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Tidskriftsartikel (refereegranskat)abstract
- Growth hormone (GH) deficiency is associated with abnormal vascular reactivity and development of atherosclerosis. GH treatment in GH deficient states restores systemic vascular resistance, arterial compliance, endothelium-dependent and endothelium-independent vasodilation, and may reverse markers of early atherosclerosis. However, very little is known about the molecular mechanisms underlying these effects. In the present study, male Sprague Dawley rats were hypophysectomized and treated for two weeks with GH (recombinant human GH, 2 mg/kg/day) or saline as s.c. injections twice daily. GH decreased aortic systolic blood pressure compared with saline-treated animals, while the diastolic blood pressure was not significantly changed. GH treatment increased cardiac output as determined by Doppler-echocardiography and the calculated systemic vascular resistance was markedly reduced. In order to identify GH-regulated genes of importance for vascular function, aortic mRNA levels were analyzed by the microarray technique and correlated to the systolic blood pressure levels. Using this approach, we identified 18 GH-regulated genes with possible impact on vascular tone and atherogenesis. In particular, mRNA levels of the inwardly rectifying potassium channel Kir6.1 and the sulfonylurea receptor 2B, which together form the vascular smooth muscle ATP-sensitive potassium channel, were both up-regulated by GH treatment and highly correlated to systolic blood pressure. Our findings establish a major role for GH in the regulation of vascular physiology and gene expression. Increased expression of the ATP-sensitive potassium channel, recently shown to be crucial in the regulation of vascular tone, constitutes a possible mechanism by which GH governs vascular tone.
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| 2. |
- Andersson, Irene, 1978, et al.
(författare)
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Endothelial dysfunction in growth hormone transgenic mice
- 2006
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 110:2, s. 217-25
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Tidskriftsartikel (refereegranskat)abstract
- Acromegaly [overproduction of GH (growth hormone)] is associated with cardiovascular disease. Transgenic mice overexpressing bGH (bovine GH) develop hypertension and hypercholesterolaemia and could be a model for cardiovascular disease in acromegaly. The aims of the present study were to investigate the effects of excess GH on vascular function and to test whether oxidative stress affects endothelial function in bGH transgenic mice. We studied the ACh (acetylcholine)-induced relaxation response in aortic and carotid rings of young (9-11 weeks) and aged (22-24 weeks) female bGH transgenic mice and littermate control mice, without and with the addition of a free radical scavenger {MnTBAP [Mn(III)tetrakis(4-benzoic acid)porphyrin chloride]}. We also measured mRNA levels of eNOS (endothelial nitric oxide synthase) and EC-SOD (extracellular superoxide dismutase). Intracellular superoxide anion production in the vascular wall was estimated using a dihydroethidium probe. Carotid arteries from bGH transgenic mice had an impaired ACh-induced relaxation response (young, 46 +/- 7% compared with 69 +/- 8%; aged, 52 +/- 5% compared with 80 +/- 3%; P < 0.05), whereas endothelial function in aorta was intact in young but impaired in aged bGH transgenic mice. Endothelial dysfunction was corrected by addition of MnTBAP in carotid arteries from young mice and in aortas from aged mice; however, MnTBAP did not correct endothelial dysfunction in carotid arteries from aged bGH transgenic mice. There was no difference in intracellular superoxide anion production between bGH transgenic mice and control mice, whereas mRNA expression of EC-SOD and eNOS was increased in aortas from young bGH transgenic mice compared with control mice (P < 0.05). We interpret these data to suggest that bGH overexpression is associated with a time- and vessel-specific deterioration in endothelial function, initially caused by increased oxidative stress and later by other alterations in vascular function.
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| 3. |
- Nyström, Henrik, 1977, et al.
(författare)
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Short-term administration of growth hormone (GH) lowers blood pressure by activating eNOS/nitric oxide (NO)-pathway in male hypophysectomized (Hx) rats
- 2005
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Ingår i: BMC Physiol. - : Springer Science and Business Media LLC. - 1472-6793. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of the study was to evaluate the acute and continuous (up to 14 days of treatment) effect of growth hormone (GH) on blood pressure (BP) regulation and to investigate the interplay between GH, nitric oxide (NO) and BP. In un-supplemented and GH supplemented hypophysectomized (Hx) male rats as well as intact rats, continuous resting mean arterial blood pressure (MAP) was measured using telemetry. Baroreceptor activity and the influences of NO on BP control were assessed during telemetric measurement. Furthermore, basal plasma and urine nitrate levels and aortic endothelial nitric oxide synthase (eNOS) expression were analysed. Endothelial function as well as vascular structure in the hindquarter vascular bed was estimated using an in vivo constant-flow preparation. RESULTS: Hypophysectomy was associated with decreased MAP (Hx: 83 +/- 3 vs Intact: 98 +/- 6 mmHg, p < 0.05) and heart rate (HR) (Hx: 291 +/- 4 vs Intact: 351 +/- 7 beat/min, p < 0.05). Endothelial dysfunction and reduced vasculature mass in the hindquarter vascular bed was found in Hx rats. GH substitution caused a further transient decrease in MAP and a transient increase in HR (14% and 16% respectively, p < 0.05). The reduction in MAP appeared to be NO dependent. Aortic eNOS expression was unchanged. GH substitution resulted in an impaired baroreceptor function. Two weeks of GH treatment did not normalise the BP, vascular structure and the endothelial function in the resistance vessels. CONCLUSION: GH substitution seems to have a short lasting effect on lowering blood pressure via activation of the NO-system. An interaction between GH, NO-system and BP regulation can be demonstrated.
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| 4. |
- Sandqvist, Madelene, 1974, et al.
(författare)
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Low adipocyte IRS-1 protein expression is associated with an increased arterial stiffness in non-diabetic males
- 2005
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Ingår i: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 180:1, s. 119-25
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Low adipocyte IRS-1 protein expression is a biomarker for insulin resistance and early atherosclerosis. However, whether IRS-1 protein expression is related to systemic arterial stiffness, is unknown. METHODS AND RESULTS: Ten non-diabetic male subjects with low adipocyte IRS-1 protein expression (LIRS) were matched with 10 non-diabetic males with normal IRS-1 protein expression (NIRS). Augmentation index (AIx) and time for reflection of pulse wave (Tr) were studied with pulse wave analysis, both in the fasting state and during a euglycemic hyperinsulinemic clamp. The LIRS-group showed an increased fasting insulin concentration (fP-insulin 71+/-4 pmol/L versus 58+/-5 pmol/L; p=0.02 (mean+/-S.E.)), whereas glucose disposal rate during the clamp (8.7+/-0.8 mg/kg LBM/min versus 10.3+/-1.3 mg/kg LBM/min; n.s.) did not differ significantly. Blood pressure, lipid parameters, adiponectin, endothelin-1 and CRP concentrations were similar. However, in the basal state, AIx was increased (129+/-4% versus 116+/-2%; p<0.02) and Tr was decreased (150+/-3 ms versus 171+/-5 ms; p<0.01), suggesting stiffer vessels in the LIRS-group. The LIRS-group exhibited an attenuated AIx response to hyperinsulinemia compared to the NIRS-group. CONCLUSIONS: The data suggest that non-obese non-diabetic men with a low adipocyte IRS-1 protein expression have an increased systemic arterial stiffness.
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