Selective inhibition of the cellular sodium pump by emicymarin and 14ß anhydroxy bufadienolides

▶ Most cardenolides and bufadienolides inhibit the sodium pump non-selectively. ▶ A synthetic bufadienolide lacking the 14-OH inhibits the sodium pump selectively. ▶ Emicymarin is a weaker inhibitor of the leucocyte than the erythrocyte sodium pump. ▶ Selectivity may explain the symptomless pump inhibition seen in human hypertension.