Acute Effects of Growth Hormone on Vascular Function in Human Subjects

Abstract

GH is involved in the long-term regulation of peripheral vascular resistance and vascular reactivity. We determined whether GH plays a role in the acute regulation of vascular function in humans. The acute vascular effects of GH were studied in eight healthy subjects according to a double-blind, placebo-controlled design. Forearm blood flow (FBF), vascular resistance, and nitric oxide (NO) production were monitored during a 4-h infusion of GH into the brachial artery at a rate chosen to raise local GH to stress levels (approximately 40 ng/ml). During GH infusion, FBF rose 75% (P < 0.05), whereas forearm vascular resistance decreased comparably (P < 0.05). These changes were paralleled by augmented forearm release of NO (P < 0.02). GH heightened the response of FBF to the endothelium-dependent vasodilator acetylcholine (Ach; P < 0.02). With the highest Ach dose, FBF reached 30.4 +/- 4.2 and 16.9 +/- 3.1 ml/dl x min in the GH and placebo studies, respectively (P < 0.005). The slopes of the dose-response curves also differed markedly (0.45 +/- 0.07 and 0.25 +/- 0.05 ml/dl x min/ microg in the GH and placebo studies, respectively; P < 0.01). GH caused an upward shift of the FBF response to the endothelium-independent vasodilator sodium nitroprusside (P < 0.01), but did not affect the slope of the dose-response curve. GH infusion did not cause any appreciable increment in the venous IGF-I concentration in the test arm. In conclusion, GH acutely lowers peripheral vascular resistance and stimulates endothelial function. These effects are mediated by activation of the NO pathway and appear to be independent of IGF-I.

The prolactin family hormones regulate vascular tone through NO and prostacyclin production in isolated rat aortic rings

“…In contrast to the findings described above, both in vitro [26] and in vivo studies [27,28] indicate that GH induces eNOSmediated NO production. In the human endothelial cell line, EAht926, high concentrations of GH regulate eNOS expression and NO production [26] , effects that also occur in human aortic endothelial cells [29] .…”

“…Clinical studies indicate that GH is one of many factors regulating vascular homeostasis [1,53] ; Napoli et al [28] demonstrated that the exogenous administration of GH induced local vasodilation in a rat model, an effect that was related to increased of NO levels and promoted endothelial sensitivity to vasorelaxants, such as ACh; however, they did not www.nature.com/aps Gonzalez C et al Acta Pharmacologica Sinica npg clarify which signaling molecules were involved but hypothesized that the local action of the hormone was responsible for the observed effects. We demonstrated that GH and PL act directly on the GHR in endothelial cells, promoting both vasodilation and NO release.…”

Low-dose growth hormone administration mobilizes endothelial progenitor cells in healthy adults

“…Indices of NO formation are low in patients with GH deficiency whereas replacement therapy with GH results in increased rates of NO synthesis [14]. GH given in vivo and in vitro stimulates eNOS gene and protein expression, as well as NO release from the endothelium [15,16]. On a molecular level, preliminary studies have suggested that the Akt pathway is involved in GH-mediated induction of eNOS activity.…”

“…(A) The number of early-outgrowth EPCs increased following growth hormone administration (13 CFU per HPF[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] to 19), (B) whereas the number of late-outgrowth EPCs did not significantly change (4 CFU per HPF[2][3][4][5][6][7][8][9][10][11] to 1 [0-4]). Data presented as median with interquartile range (N = 10).…”

Growth hormone and growth hormone gene of the American mink (Neovison vison) – the current state of knowledge of one of the key hormones in one of the most intensively economically exploited species

“…The growth hormone also conditions the proper composition of the body, mostly within the volume and topography of the fat tissue, as well as it regulates the proper development and functioning of many organs and organ systems, like heart and circulatory system, brain and nervous system, stomach and digestive system, kidneys and excretory system, as well as lungs and respiratory tract (Nass et al, 1995;Merola et al, 1996;Parks et al, 1998;Waters et al, 1999;Frago et al, 2002;Napoli et al, 2003;Dattani, Preece, 2004;Biller, 2007;Krysiak, Okopień, 2007;Harvey, 2010).…”