What is the function of an ACE inhibitor?

• A. A medication that increases enzyme activity
• B. A medication that lowers heart rate by increasing activity
• C. A medication that blocks LDL receptors
• D. A medication that slows enzyme activity

Answer: (D)

ACE inhibitors block the action of angiotensin-converting enzyme (ACE). This enzyme normally converts angiotensin I to angiotensin II, a strong vasoconstrictor. By inhibiting ACE, less angiotensin II is produced, so blood vessels relax and blood pressure falls. They also reduce aldosterone release, which lowers blood volume. In short, these drugs slow the enzyme’s activity by preventing it from doing its job, rather than increasing activity or affecting LDL receptors or heart rate directly.