Arginine Vasopressin Potentiates Adrenocorticotropin

A bstract. Arginine vasopressin (AVP) stimulates ACTH release in man and acts synergistically with synthetic ovine corticotropin-releasing factor (oCRF) in vitro. This study was designed to examine in man the combined effects of synthetic AVP (10 U intramuscularly) and oCRF (1 gg/kg intravenously) on ACTH release. Five normal male volunteers participated in five separate experiments: (a) AVP alone; (b) oCRF alone; (c) AVP followed by oCRF 15 min later; (d) simultaneous AVP and oCRF; and (e) insulin-induced hypoglycemia. Plasma immunoreactive ACTH (IR-ACTH) and IR-cortisol were measured for 4 h after injection of each hormone; basal levels for all subjects were .9±1.2 pg/ml and 4.9±0.4 ,gg/dl (mean±SE), respectively. AVP and oCRF, when given individually, caused rapid rises in IR-ACTH to similar peak levels of 25±6.6 and 33±4.6 pg/ml, respectively. AVP given 15 min before oCRF caused a 2.6-fold potentiation ofthe oCRF response, with a peak IR-ACTH of 85±4.6 pg/ml. AVP given at the same time as oCRF produced a fourfold potentiation of the peak IR-ACTH