Vasopressin-Induced ACTH Secretion in Man

Abstract

In order to determine the mechanism by which vasopressin administration produces adrenal cortical secretion in man, the response in plasma ACTH concentration to the intramuscular injection of synthetic lysine-8-vasopressin was studied in 7 normal subjects. ACTH was assayed by the ability of a plasma sample to increase the adrenal content of corticosterone in the hypophysectomized rat. Mean base line ACTH concentrations of 1.21±0.07 and 1.06±0.11 increased rapidly following vasopressin administration to peak at 3.96±2.4 mU ACTH/100 ml plasma 20 min following the injection. Normal plasma to which vasopressin was added in concentration of 10 mU/ml (equivalent to the maximum possible concentration present in the subject's plasma) produced no significant increase in adrenal corticosterone content in the assay animal. When the concentration of added vasopressin was increased to 100 mU/ml there was a small but significant increase in adrenal corticosterone content. It is concluded that vasopressin-induced steroidogenesis in man is principally due to ACTH secretion.