Responses of plasma growth hormone and corticosteroids to insulin and arginine with or without prior administration of dexamethasone.

ABSTRACT With a single iv injection of 0.1 U/kg body weight of insulin or a 30-min iv infusion of 0.5 g/kg body weight of arginine monochloride, plasma growth hormone (HGH) of healthy young men increased to 45.1 ± 7.52 (mean±sd) ng/ml and 36.6 ± 9.67 ng/ml, respectively. Plasma corticosteroids, on the other hand, increased by 9.0 ± 3.78 μg/100 ml with insulin, and showed a gradual decline, which seemed to be a normal diurnal rhythm, with arginine. Administration of 9 mg/day of dexamethasone for 2 days suppressed the insulininduced HGH release, but did not affect the arginine-induced HGH release. These data suggest that these 2 stimuli for HGH release exert their actions through different mechanisms.