How does Digoxin primarily work in the body?

Digoxin primarily exerts its effects by inhibiting the Na+/K+ ATPase pump in cardiac cells. This inhibition leads to an increase in intracellular sodium levels. As sodium accumulates inside the cell, it reduces the gradient for the Na+/Ca2+ exchanger, causing calcium levels to rise within the cell. The increase in intracellular calcium enhances the force of contraction of the heart muscle, making it a positive inotropic agent.

This mechanism is particularly important in treating heart failure and certain arrhythmias, as it improves the efficiency of the heart's contractions and helps alleviate symptoms associated with these conditions. Additionally, the increased calcium availability contributes to better cardiac output, which is critical for patients with compromised heart function.

The other options do not accurately describe the primary action of digoxin. While some medications may act on calcium channels or influence vascular resistance or sodium excretion, these actions are not the primary mechanisms of digoxin.