Dopaminergic regulation of extrarenal potassium metabolism.

The effect of the dopaminergic system on renal and extrarenal potassium metabolism has been poorly characterized. To examine this problem, 2-hour renal clearance studies were performed in 7 healthy men. Each subject served as his own control and participated in three studies. Subjects received (a) a 2-hour potassium chloride (0.75 mEq/kg) intravenous infusion; (b) the same KCl infusion with dopamine (4 micrograms/kg . min), and (c) the same KCl infusion with the dopaminergic blocker metoclopramide (10 mg i.v. bolus). The rise in plasma potassium during the KCl infusion was significantly lower in the subjects receiving metoclopramide compared to the controls who received KCl alone (0.29 +/- 0.07 vs. 0.52 +/- 0.06 mEq/l, p less than 0.005). During the first 2 h after metoclopramide the increase in UKV and total potassium excretion was slightly, although not significantly, lower than in the KCl-alone group (154 +/- 15 vs. 168 +/- 15 mEq/min, NS). Since the increment in plasma K concentration following metoclopramide was less than in the controls despite a slightly reduced rate of KCl excretion, the improvement in potassium tolerance resulted from an enhanced translocation of potassium from the extra- to intracellular compartment (86 +/- 2 vs. 77 +/- 3%, p less than 0.01). There were no significant differences in venous pH, serum bicarbonate concentration or plasma insulin as compared to the control group.(ABSTRACT TRUNCATED AT 250 WORDS)