Lisinopril exerts its antihypertensive effect by directly inhibiting which enzyme or molecule?

Correct answer: C. Angiotensin-converting enzyme (ACE)

• A. Aldosterone is downstream of ACE and angiotensin II; its levels fall as a consequence of ACE inhibition but it is not the direct target of lisinopril.
• B. Renin is inhibited by aliskiren (a direct renin inhibitor), not by lisinopril.
• C. Correct. Lisinopril is an ACE inhibitor — it directly inhibits angiotensin-converting enzyme (ACE), preventing the conversion of angiotensin I to angiotensin II, thereby reducing vasoconstriction and aldosterone secretion.
• D. Angiotensin I is the substrate, not the target. Lisinopril prevents ACE from converting angiotensin I to angiotensin II.