Combined Effects of Digitalis Therapy and of Plasma Bicarbonate on Human Red Cell Sodium and Potassium

Abstract

Erythrocyte sodium and potassium were studied in 28 patients treated with digitalis glycosides. Red cell sodium increased when digitalis therapy was initiated, and fell to normal when digitalis therapy was stopped. The degree of intracellular sodium accumulation was dependent on plasma bicarbonate concentration. The combination of alkalosis and digitalis therapy may lead to an exceedingly high sodium content of the red cells. The findings are explained by the inhibitory effect of digitalis glycosides on active sodium transport and of the ability of bicarbonate to increase passive sodium permeability. No systematic changes of red cell potassium occurred in this material, probably because the inhibitory effect of digitalis on active potassium transport is counteracted by the previously described stimulatory effect of increased intracellular sodium on the same transport mechanism.