Which statement best describes the mechanism of action of angiotensin II receptor blockers (ARBs)?

Which statement best describes the mechanism of action of angiotensin II receptor blockers (ARBs)?

• A. Block angiotensin II type 1 receptors, reducing vasoconstriction and aldosterone release.
• B. Inhibit angiotensin-converting enzyme.
• C. Block aldosterone receptors in the kidney.
• D. Increase renin production.

Answer: (A)

Angiotensin II receptor blockers work by selectively blocking the AT1 receptor. This prevents angiotensin II from causing vasoconstriction and from stimulating the adrenal glands to release aldosterone. With the receptor blocked, blood vessels relax and aldosterone-mediated sodium and water retention decrease, leading to lower blood pressure and reduced fluid volume. They differ from ACE inhibitors, which lower the amount of angiotensin II produced, and from mineralocorticoid receptor antagonists, which block aldosterone’s actions at the kidney. Because blocking the receptor removes Ang II signaling, renin levels can rise as a feedback response, but the key action producing the therapeutic effect is receptor blockade.

Angiotensin II receptor blockers work by selectively blocking the AT1 receptor. This prevents angiotensin II from causing vasoconstriction and from stimulating the adrenal glands to release aldosterone. With the receptor blocked, blood vessels relax and aldosterone-mediated sodium and water retention decrease, leading to lower blood pressure and reduced fluid volume. They differ from ACE inhibitors, which lower the amount of angiotensin II produced, and from mineralocorticoid receptor antagonists, which block aldosterone’s actions at the kidney. Because blocking the receptor removes Ang II signaling, renin levels can rise as a feedback response, but the key action producing the therapeutic effect is receptor blockade.