Spironolactone blocks the action of which main hormone involved in blood pressure?

• A. Angiotensin II
• B. Aldosterone
• C. Vasopressin
• D. Renin

Answer: (B)

Spironolactone works by blocking the action of aldosterone, the mineralocorticoid hormone that promotes sodium reabsorption and potassium excretion in the distal nephron. By antagonizing the mineralocorticoid receptor, spironolactone prevents aldosterone from increasing the activity of ENaC channels and Na+/K+-ATPase, which reduces sodium reabsorption, promotes water loss, and lowers blood pressure while helping retain potassium.

The other options aren’t the direct target: angiotensin II triggers aldosterone release and has other effects like vasoconstriction, vasopressin (ADH) mainly increases water reabsorption in the collecting ducts, and renin is an enzyme that starts the cascade, not the hormone whose action spironolactone blocks.