What is the primary mechanism of action of ACE inhibitors?

• A. Inhibit the reuptake of serotonin
• B. Inhibit the conversion of angiotensin I to angiotensin II
• C. Block calcium channels
• D. Activate beta-1 adrenergic receptors

Answer: (B)

ACE inhibitors primarily function by inhibiting the conversion of angiotensin I to angiotensin II. This mechanism is crucial because angiotensin II is a potent vasoconstrictor that plays a significant role in increasing blood pressure. By blocking this conversion, ACE inhibitors lead to decreased levels of angiotensin II, resulting in vasodilation, reduced blood pressure, and decreased workload on the heart.

The therapeutic advantages of this mechanism are particularly evident in conditions such as hypertension and heart failure, where reducing blood pressure and minimizing strain on the cardiovascular system can improve outcomes. Additionally, lower levels of angiotensin II can lead to reductions in aldosterone secretion, further enhancing the excretion of sodium and water, which contributes to lowering blood volume and pressure.

This action differentiates ACE inhibitors from other drug classes, such as those that inhibit the reuptake of serotonin, block calcium channels, or activate beta-1 adrenergic receptors, which do not specifically target the renin-angiotensin-aldosterone system and its associated effects on blood pressure regulation.