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

Arginine vasopressin stimulates the secretion of adrenocorticotropin. A direct stimulatory effect of AVP on cortisol as well as aldosteron 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 < 0.001) linear correlation between plasma ACTH and plasma cortisol was observed. The regression coefficients were not different (p > 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.