Dopaminergic control of serum potassium.

Metoclopramide, a dopaminergic inhibitor, injected in 9 normal volunteers, was followed by a prompt decrease of serum potassium (10--20 min; p less than 0.01) and by an increase of plasma aldosterone (p less than 0.01). Renin slightly increased at 45 min (p less than 0.05); insulin and cortisol did not show any significant increase. The urinary excretion of potassium rose after metoclopramide (p less than 0.05). A bolus of aldosterone (250 micrograms i.v.) in 4 normal subjects was not followed by any modification of serum potassium, but increased urinary potassium excretion (p less than 0.05); the injection of metoclopramide in two patients with an aldosterone-secreting adenoma of the adrenal and in one patient with Addison's disease induced a decrease of serum potassium in absence of any modification of plasma aldosterone. The decrease of serum potassium after metoclopramide is not explained by changes of aldosterone or insulin, considered the most important hormonal controls of potassium. The rapidity of potassium decrease implies a change of distribution of potassium between extra- and intracellular compartments, which, in turn, may stimulate aldosterone secretion. It is conceivable that the dopaminergic system has a role in the control of serum potassium.