Cardiac effects of hexarelin in hypopituitary adults

Growth hormone (GH)-releasing peptides possess specific pituitary, hypothal amic, and myocardial receptors. Seven adult male patients with GH deficienc y (GHD) (age, mean +/- S.E.M.: 42.0 +/- 4.0 year) were studied by equilibri um radionuclide angiocardiography after i.v. administration of hexarelin, a peptide GH secretagogue. Data for these patients were compared with those for nine adult male controls (37.0 +/- 2.7 year). The GH response to hexare lin was negligible in patients with GHD compared to control subjects (CS) ( peak: 1.9 +/- 0.9 vs. 45.7 +/- 3.6 mu g/l, P < 0.001). Basal left ventricul ar ejection fraction (LVEF) in patients with GHD was lower than that in CS (50 +/- 1% vs. 63.2%, P < 0.001). Hexarelin administration increased LVEF b oth in patients with GHD and in CS (peak: 57 +/- 2 vs. 70 +/- 2, respective ly, P < 0.05 vs. baseline) without changing catecholamine levels, mean bloo d pressure (MBP), or cardiac output in either group. In conclusion, the acu te administration of hexarelin exerts a short-lasting positive inotropic ef fect in humans, probably GH-independent and mediated by specific myocardial receptors for GH secretagogues. (C) 1999 Elsevier Science B.V. All rights reserved.