Pharmacology In terms of the ability of drugs like digoxin to increase cardiac contractility, their primary action on cardiac cells is A activation of adenylyl cyclase B inactivation of Na channels C activation of the slow Ca channel D inhibition of Na/K-ATPase 💡 Explanation In terms of the ability of drugs like digoxin to increase cardiac contractility, their primary action on cardiac cells is ✓ Correct Answer: D. inhibition of Na/K-ATPase