Template:Digoxin mechanism

Digoxin’s inhibits of the Na+/K+ ATPase, in the myocardium causing an increase in intracellular sodium levels, resulting in a reversal of the action of the sodium-calcium exchanger. The exchanger normally imports three extracellular sodium ions into the cardiac myocyte in exchange for one intracellular calcium being exported. By inhibiting the ATPase sodium accumulates intracellularly and is exchanged for Calcium. The reversal of this exchange causes an increase in the intracellular calcium concentration increasing contractility. There is also a lengthening of phase 4 and phase 0 of the cardiac action potential which ultimately decreases heart rate.