Na+/K+-ATPase as the digitalis receptor

Abstract The cardiac glycosides are used extensively in the treatment of heart failure yet have a very low therapeutic index. It is generally believed that digitalis action on cardiac muscle is mediated via binding to a specific receptor site present on the membrane-bound enzyme, Na + /K + -ATPase. Consequent inhibition of the enzyme blocks the Na + /K + pump, thus initiating the inotropic responses. However, certain experimental data apparently cannot be completely explained by this phenomenon. Kurt Repke and Werner Schonfeld, describe their model for the biochemical mode of digitalis action which can account for all these apparent discrepancies. They also explain how separation of the effects of cardiac glycosides on sympathetic nerve terminalis and cardiac muscle may lead to the design of safer and more specific drugs.