Dopamine selectively inhibits aldosterone responses to angiotensin II in humans

Previous studies have suggested that dopamine may have an important role as an inhibitor of aldosterone secretion in humans. Recent studies have also suggested that the adrenergic nervous system may have an important role in controlling aldosterone secretion. The present study investigated the effects of dopamine on aldosterone secretion in response to angiotensin II, with and without pretreatment with propranolol, and to adrenocorticotropic hormone, another known stimulator of aldosterone secretion. Nine normal subjects in balance at 10 mEq sodium intake received dopamine (4 micrograms/kg/min) or vehicle for 270 minutes on 2 consecutive days on three separate occasions. After 120 minutes of dopamine infusion, the subjects received a 30-minute intravenous infusion of angiotensin II (in cumulative doses of 0.5, 1, 2, 4, and 6 pmol/kg/min), angiotensin II after oral pretreatment with propranolol, or adrenocorticotropic hormone (in cumulative doses of 0.5, 1, 2, and 5 U/hr). Aldosterone responses to 2, 4, and 6 pmol/kg/min of angiotensin II (without propranolol) were greater in vehicle-treated than in dopamine-treated subjects (p less than 0.05), as was the slope of the angiotensin II-vehicle dose-response curve (0.46, p less than 0.05). Propranolol suppressed the aldosterone response to angiotensin II, but dopamine still inhibited the response. Aldosterone and cortisol secretion were stimulated equally by adrenocorticotropic hormone in dopamine-treated and vehicle-treated groups. These results suggest that dopamine selectively inhibits the aldosterone response to angiotensin II and that this response is not mediated by teh activity of dopamine at beta-adrenergic receptors.