Augmentation by propranolol of growth hormone-releasing hormone-(1-44)-NH2-induced growth hormone release in normal short and normal children.

The effect of a 90-min iv infusion of propranolol, a beta-adrenergic antagonist (0.2 mg/kg BW), on basal plasma GH levels and the GH responses to an iv bolus injection of GH-releasing hormone-(1-44)-NH2 (GHRH; 1 microgram/kg BW) was examined in 10 prepubertal children (6 short but otherwise normal and 4 normal). The iv injection of GHRH resulted in significant increases in plasma GH, comparable to those after either insulin-induced hypoglycemia or arginine infusion. Only a small and inconsistent increase in plasma GH levels occurred during the iv infusion of propranolol, whereas simultaneous administration of propranolol with GHRH caused marked enhancement of GHRH-induced GH release in all subjects. The difference between the plasma GH response to GHRH given with propranolol and the response to GHRH given with 0.9% saline was significantly greater than that between the plasma GH level after propranolol and that after 0.9% saline infusion without GHRH injections. There was no difference in plasma GH responses to GHRH, propranolol, or both in the normal short children or normal children. These findings indicate that beta-adrenergic blockade potentiates GHRH-induced GH secretion in prepubertal children.