Enhanced response of plasma aldosterone to metoclopramide in essential hypertension

Aldosterone responses to posture and the dopamine antagonist, metoclopramide, were studied in seven normotensive controls and 12 patients with essential hypertension. Both groups had similar basal supine plasma renin activity and aldosterone levels. Aldosterone levels of the hypertensive patients were greater than those of the controls 10 min after assuming an upright posture but indistinguishable at 120 min. Metoclopramide induced a peak fourfold increase above basal aldosterone levels in the hypertensive group as compared to a peak twofold increase observed in the normotensive controls. Mean 120-min integrated aldosterone response area for the hypertensives (237 ± 44 10^-10 mol min/l) was greater (P < 0.05) than that for normotensive subjects (106 ± 32 10^-10 mol min/l). Simultaneous cortisol, plasma renin activity, and serum potassium levels were unaffected by metoclopramide. It is concluded that dopaminergic modulation of aldosterone secretion may be altered in essential hypertension.