What is the primary mechanism of action for ACE inhibitors?

The primary mechanism of action for ACE inhibitors is that they inhibit the conversion of angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor and plays a significant role in regulating blood pressure, stimulating aldosterone secretion, and promoting sodium and water retention. By blocking this conversion, ACE inhibitors effectively reduce the levels of angiotensin II in the body, leading to vasodilation, decreased blood pressure, and reduced strain on the heart.

This action is crucial for the treatment of hypertension and heart failure, as it helps to alleviate the cardiovascular workload and improves overall heart function. Additionally, the reduction in angiotensin II levels contributes to a decrease in the release of aldosterone, which further reduces blood volume and pressure.

In contrast, the other options present mechanisms that are either unrelated to ACE inhibitors or describe actions associated with different classes of medications, such as calcium channel blockers or medications that stimulate insulin secretion.