<prompt> The biochemical mechanism of action of digitalis is associated withAn increase in conduction from Atrium to ventricleAn increase in ATP synthesisAn increase in systolic intracellular calcium levelsA block of calcium channel  <response>: Digitalis medicines strengthen the force of the heabeat by increasing the amount of calcium in the heas cells. Calcium stimulates the heabeat. ... Digitalismedicines control irregular hea rhythms called arrhythmias by slowing the signals that sta in the sinoatrial SA node. Refer katzung 11e p 214 