Stimulation of steroid secretion by adrenocorticotropin injections and by arginine vasopressin infusions: no evidence for a direct stimulation of the human adrenal by arginine vasopressin.

Abstract

Arginine vasopressin stimulates the secretion of adrenocorticotropin. A direct stimulatory effect of AVP on cortisol as well as aldosterone secretion has been postulated by several investigators. To study the possible role of a direct stimulatory action of AVP on the adrenal cortex, normal volunteers were treated with incremental injections of ACTH or with incremental infusions of AVP which raised plasma AVP levels to a maximum of 256 +/- 16 pmol/l. In both situations, a significant (p less than 0.001) linear correlation between plasma ACTH and plasma cortisol was observed. The regression coefficients were not different (p greater than 0.5). Plasma aldosterone was stimulated by both treatments, but the weakly positive correlation between plasma ACTH and plasma aldosterone was not significant for either stimulus. Thus, in man, a direct stimulatory effect of AVP on cortisol secretion cannot be demonstrated. A direct effect of AVP on aldosterone cannot be definitely excluded, but is certainly of minor importance.