Digitalis has positive inotropic effect-by the virtue of its effect on:: (A) Na+ K+ ATPase pump, (B) Na Glucose channels, (C) H+K+ ATPase pump, (D) Calcium Pump
Answer is A. Digitalis binds selectively to Na+ K+ATPase and inhibits this pump. 
Thus it increases intracellular Na+ and decreases extrusion of Ca2+