Growth hormone, vascular reactivity, and heart failure

Abstract

The growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis plays a relevant role in the regulation of vascular growth and function, as demonstrated by the data obtained in GH-deficient patients, in whom endothelial function is severely impaired. The treatment of these patients with GH is able to restore a normal endothelial function. Patients affected by congestive heart failure (CHF) are also characterized by endothelial dysfunction. Such a defect represents a key factor in the progression of the disease. Therefore, the possibility of using GH to correct endothelial dysfunction in patients with CHF has been proposed. Experimental data have demonstrated that chronic GH administration improves endothelial dysfunction in CHF patients. On the other hand, GH administration in normal healthy volunteers has been shown to positively affect endothelial function after a few hours of infusion, suggesting that GH can rapidly modify vascular functions. The mechanisms involved in the regulation of vascular function by GH are at the moment not completely clear. However, the positive effect of GH on endothelial dysfunction may be linked to a direct effect of GH on endothelial cells, an IGF-I-mediated effect, an increase in cardiac output, and a decrease of cytokine activation.