How does inhibition of the Na⁺/K⁺ ATPase increase the force of heart muscle contraction?
A)It increases cytosolic Na⁺ and therefore decreases Ca²⁺ export.
B)It increases cytosolic K⁺ and therefore decreases Ca²⁺ export.
C)It decreases cytosolic Na⁺ and therefore decreases Ca²⁺ export.
D)It decreases cytosolic K⁺ and therefore decreases Ca²⁺ export.

Question

Quizplus · Accepted Answer

Inhibition of Na+/K+ ATPase leads to an increase in cytosolic Na+ levels. This increase in cytosolic Na+ maintains a high concentration of Na+ in the cell and reduces the electrochemical gradient for Na+ entry during the next action potential. This alteration of Na+ concentration leads to the decrease of the export of intracellular Ca2+ through the Na+/Ca2+ exchanger, increasing cytosolic Ca2+ and increasing the force of heart muscle contraction.

How Does Inhibition of the Na⁺/K⁺ ATPase Increase the Force