Role of dopamine in the angiotensin II-induced vasopressin release in the conscious dehydrated dog

Abstract

The effect of the dopamine antagonist, haloperidol, on arginine-vasopressin (AVP) release induced by angiotensin II was studied in six dehydrated conscious dogs. Angiotensin II (10 ng/kg per min) alone caused a twofold increase (P<0·05) in plasma AVP concentration, a 25 mmHg increase (P<0·01) in mean arterial blood pressure (ABP) and a 70% decrease (P<0·01) in plasma renin activity (PRA). In the presence of haloperidol (3 μg/kg per min), angiotensin II caused similar changes in mean ABP (+25 mmHg; P<0·01) and PRA (−65%, P<0·01), but a small insignificant decrease in plasma AVP (−22%). The AVP response to angiotensin II in the presence of haloperidol was significantly (P<0·05) different from its response to angiotensin II alone. Neither haloperidol alone nor the two vehicles had any effect on plasma AVP or mean ABP but PRA dropped slightly. The results suggest that a dopaminergic mechanism may be involved in angiotensin II-induced AVP release.