[The interaction of the converting-enzyme inhibitor captopril with cardiac glycosides in the rat kidney].

Strophanthin (0.1 mg.kg, i.v.) and digoxin (0.1 mg/kg, i.v.) moderately increase blood supply of the renal cortical and medullary layers in unconscious rats and enhance renal excretion of sodium and water. Preadministration of the converting enzyme inhibitor captopril (10 mg/kg/day, per os, for 6 days) promoted vascular dilatation in the inner and outer areas of the medulla, which occurred under the action of these agents and substantially increased their natriuretic and diuretic effects. It is concluded that the renin-angiotension system is directly involved into the mechanism of action of cardiac glycosides in the kidneys, acting as a modulator that prevents their vasodilating and tubular effects.