What is the key mechanism of action for ACE inhibitors?

ACE inhibitors work primarily by inhibiting the angiotensin-converting enzyme (ACE), which plays a crucial role in the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure. By blocking ACE, these medications prevent the conversion of angiotensin I, an inactive precursor, into angiotensin II, a potent vasoconstrictor. Angiotensin II increases blood pressure by constricting blood vessels and stimulating the release of aldosterone, which promotes sodium and water retention.

With the synthesis of angiotensin II inhibited, the resultant effect is vasodilation and reduced blood volume, both of which help lower blood pressure. This mechanism is particularly beneficial for individuals with hypertension and heart failure, as it can lead to improved cardiac output and reduced workload on the heart.

Other options do not accurately represent the primary action of ACE inhibitors. While increasing renal blood flow and decreasing sodium reabsorption can be seen with certain types of antihypertensives, they are not direct effects of ACE inhibition. Additionally, blocking beta-adrenergic receptors is characteristic of a different class of medications known as beta-blockers.