Which of the following actions best explains the potassium-sparing effect of triamterene in the 66-year-old woman with systolic cardiac failure?

Correct Answer: B

Rationale: The correct answer is B: Blockade of Na+ channels in the collecting duct. Triamterene is a potassium-sparing diuretic that works by inhibiting the epithelial sodium channels (ENaC) in the collecting duct of the nephron. By blocking these channels, triamterene reduces sodium reabsorption, leading to decreased potassium excretion. This mechanism helps maintain potassium levels in the body, making it an effective treatment for conditions like systolic cardiac failure where potassium loss is a concern. Summary: A: Enhancement of K+ reabsorption in the proximal tubule - This is incorrect as triamterene does not act on the proximal tubule for potassium-sparing effects. C: Enhancement of K+ reabsorption in the loop of Henle - This is incorrect as triamterene does not primarily affect potassium reabsorption in the loop of Henle. D: Blockade of aldosterone receptors in the collecting duct - This is

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.