Which diuretic class is potassium-sparing and antagonizes aldosterone receptors in the collecting ducts?

Which diuretic class is potassium-sparing and antagonizes aldosterone receptors in the collecting ducts?

• A. Loop diuretic; inhibits Na-K-2Cl cotransporter.
• B. Thiazide diuretic; inhibits NaCl reabsorption.
• C. Osmotic diuretic; increases water excretion.
• D. Potassium-sparing diuretic; aldosterone receptor antagonist in collecting ducts.

Answer: (D)

Potassium-sparing diuretics that antagonize aldosterone receptors in the collecting ducts work by blocking aldosterone’s action on its mineralocorticoid receptor there. Aldosterone normally promotes sodium reabsorption and potassium secretion in the collecting ducts by increasing ENaC channels and Na+/K+-ATPase activity. Blocking this receptor reduces sodium reabsorption and decreases potassium loss, yielding a potassium-sparing effect. This mechanism is distinct from other diuretic classes: loop diuretics inhibit the Na-K-2Cl cotransporter in the thick ascending limb, thiazides inhibit NaCl reabsorption in the distal tubule, and osmotic diuretics cause water excretion by creating an osmotic effect. Thus, an aldosterone receptor–antagonist in the collecting ducts is the class that preserves potassium while promoting diuresis.

Potassium-sparing diuretics that antagonize aldosterone receptors in the collecting ducts work by blocking aldosterone’s action on its mineralocorticoid receptor there. Aldosterone normally promotes sodium reabsorption and potassium secretion in the collecting ducts by increasing ENaC channels and Na+/K+-ATPase activity. Blocking this receptor reduces sodium reabsorption and decreases potassium loss, yielding a potassium-sparing effect. This mechanism is distinct from other diuretic classes: loop diuretics inhibit the Na-K-2Cl cotransporter in the thick ascending limb, thiazides inhibit NaCl reabsorption in the distal tubule, and osmotic diuretics cause water excretion by creating an osmotic effect. Thus, an aldosterone receptor–antagonist in the collecting ducts is the class that preserves potassium while promoting diuresis.