<prompt> The biochemical mechanism of action of digitalis is associated with:An increase in conduction from atrium to ventricleAn increase in ATP synthesisAn increase in systolic intracellular calcium levelsA block of calcium channels  <response>: 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 