Action of Digitalis on the Kidney. ∗

Abstract

It has never been clearly established whether or not digitalis has a diuretic action on the kidney aside from the secondary diuresis that occurs as a result of improvement in the circulation in congestive heart failure. A number of workers failed to obtain any direct diuretic action. Schwartz 1 was unable to produce diuresis in normal individuals with digitalis; Cushny 2 and Cohn 3 failed to obtain any increase in urinary flow in cardiac patients without edema, and Miller 4 found that digitalis had no effect on renal edema. Cushny and Lambi 5 concluded from their studies that the members of the digitalis group produced no diuresis in normal animals. However, Phillips and Bradford, 6 Pfaff 7 and Gremels 8 claimed to have obtained a diuretic action in animals with small doses of digitalis. Recently Bartram 9 has also reported that digitan has a direct diuretic action, following its injection into one renal artery.

The discrepancy in previous results led us to reinvestigate the subject. In anesthetized animals, conditions vary from time to time sufficiently to alter the urinary flow, so that results ascribed to the action of an injected drug might be coincidental. It seemed to us that the direct action of a drug on the kidney might be more readily estimated by injecting the drug directly into one renal artery and determining the urine flow of that kidney for a short period of time. Any indirect action or any spontaneous change could be eliminated by using the urine flow of the opposite kidney as a control for comparison.

Fourteen medium-sized male dogs were used. No food was given the animals for 12 hours preceding the operation, but water was urged. The animals were lightly anesthetized with nembutal intravenously (25 mg. per kilo) and this was supplemented when necessary during the course of the experiment with further injections of 5 mg. per kilo.

Summary. The immediate effects of digitalis preparations, digalen, digitalone and ouabain, on Urine secretion were studied in anesthetized dogs by comparing the urine flow of the kidney into whose renal artery the drug was injected with the urine flow of the opposite kidney. In no instance did the digitalis preparation produce a diuretic action, in fact in most cases an inhibition of urinary secretion was noted.