Renal effects of methoxyverapamil in anesthetized rats

The purpose of these experiments was to determine the renal effects of methoxyverapamil (D-600). Three groups of rats were anesthetized with sodium pentobarbital and given 0, 0.85 or 1.69 nmol/min of methoxyverapamil i.v. Increases in urine flow and Na, K and Ca excretory rates occurred, in an apparently dose-dependent manner. Plasma Na and arterial renin concentration decreased at both doses and, at the higher dose, mean arterial blood pressure and effective renal plasma flow decreased while plasma K increased. Plasma Ca, glomerular filtration rate, filtration fraction and total renal plasma flow were not affected. The findings that methoxyverapamil increased urine flow and electrolyte excretion without changing glomerular filtration rate are consistent with the hypothesis that methoxyverapamil acts directly on tubular reabsorptive mechanisms. These effects, and the effect on plasma renin concentration, could contribute to the beneficial effects of this and other Ca entry antagonists in the treatment of hypertension.