Which of the following accurately describes the mechanism of action of digoxin?
A. Digoxin binds to and inhibits Na/K ATPase. Inhibition of Na/K ATPase increases intracellular concentration of Na+ ions. Increased intracellular Na+ decreases the activity of the Na/Ca exchanger and allows intracellular Ca++ concentrations to increase. Increased intracellular Ca++ increases the formation of actinomyosin and increases the force of myocardial contractions.
B. Digoxin binds to and inhibits Na/K ATPase. Inhibition of Na/K ATPase decreases intracellular concentration of Na+ ions. Decreased intracellular Na+ increases the activity of the Na/Ca exchanger and allows intracellular Ca++ concentrations to decrease. Decreased intracellular Ca++ increases the formation of actinomyosin and increases the force of myocardial contractions.
C. Digoxin stimulates Na/K ATPase. Stimulation of Na/K ATPase increases intracellular concentration of Na+ ions. Increased intracellular Na+ decreases the activity of the Na/Ca exchanger and allows intracellular Ca++ concentrations to increase. Increased intracellular Ca++ increases the formation of actinomyosin and increases the force of myocardial contractions.
D. None of the above are correct.
Answer: A
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