Which statement best describes the effect of digoxin on Na+/K+ ATPase?

Which statement best describes the effect of digoxin on Na+/K+ ATPase?

• A. It increases the activity of the pump
• B. It inhibits the pump's function
• C. It has no effect on the pump
• D. It converts the pump to facilitated diffusion

Answer: (B)

Digoxin is a cardiac glycoside that primarily functions by inhibiting the Na+/K+ ATPase pump. This enzyme is responsible for pumping sodium ions out of the cell and potassium ions into the cell, maintaining the ionic balance across the plasma membrane, which is crucial for numerous cellular functions, especially in cardiac muscle cells. When digoxin inhibits the Na+/K+ ATPase, there is a decrease in the extrusion of sodium from the cell. This leads to an increase in intracellular sodium concentration. As a consequence, the sodium-calcium exchanger (NCX), which typically transports calcium out of the cell in exchange for sodium, is affected. With elevated sodium levels inside the cell, the exchange mechanism is hindered, causing an increase in intracellular calcium. This rise in calcium is what contributes to the positive inotropic effect that enhances the force of cardiac contractions. Thus, stating that digoxin inhibits the pump’s function accurately highlights its biochemical action and therapeutic context in heart failure treatment.

Digoxin is a cardiac glycoside that primarily functions by inhibiting the Na+/K+ ATPase pump. This enzyme is responsible for pumping sodium ions out of the cell and potassium ions into the cell, maintaining the ionic balance across the plasma membrane, which is crucial for numerous cellular functions, especially in cardiac muscle cells.

When digoxin inhibits the Na+/K+ ATPase, there is a decrease in the extrusion of sodium from the cell. This leads to an increase in intracellular sodium concentration. As a consequence, the sodium-calcium exchanger (NCX), which typically transports calcium out of the cell in exchange for sodium, is affected. With elevated sodium levels inside the cell, the exchange mechanism is hindered, causing an increase in intracellular calcium. This rise in calcium is what contributes to the positive inotropic effect that enhances the force of cardiac contractions.

Thus, stating that digoxin inhibits the pump’s function accurately highlights its biochemical action and therapeutic context in heart failure treatment.