Acetyldigitoxin is cardiac glycoside and an inhibitor of the Na/K ATPase with an IC value of 5 nM in isolated rat pinealocytes. This inhibition results in loss of the transmembrane Na gradient, which decreases activity of the Na/Ca exchanger, increasing intracellular calcium levels, inotropy, and cardiac force. Formulations containing acetyldigitoxin have been used for the treatment of heart failure and chronic atrial fibrillation.