The biochemical mechanism of action of digitalis is associated with:: (A) An increase in conduction from atrium to ventricle, (B) An increase in ATP synthesis, (C) An increase in systolic intracellular calcium levels, (D) A block of calcium channels
Answer is C. Digoxin is a cardiac glycoside. It directly inhibits Na-K ATPase and increases intracellular Na and decrease the extrusion of calcium. Thus increases intracellular Calcium. By increasing the calcium content and sodium content, force of contraction increases. (Ref-Essential of medical pharmacology K D TRIPATHI 6 Edition)