Plasma renin activity and aldosterone concentration in sodium-depleted cattle following ACTH or metoclopramide injection.

Adrenocorticotropic hormone (ACTH) treatment (7 micrograms X kg-1 body weight) induced an increase in plasma aldosterone concentration in both Na-deficient heifers (following saliva loss after right parotid duct cannulation) and Na-replete heifers, but had no significant effect on plasma renin activity in either of these groups. The dopamine antagonist, metoclopramide, injected i.v. (1 mg X kg-1 body weight) did not modify plasma renin activity, aldosterone or cortisol concentrations in either group. These results indicate that dopamine did not play a major role in the regulation of aldosterone secretion in Na-replete or Na-depleted heifers.