What is the main mechanism of action of ACE inhibitors?

ACE inhibitors primarily work by inhibiting the conversion of angiotensin I to angiotensin II. This action is crucial in regulating blood pressure and fluid balance in the body. When angiotensin I is converted to angiotensin II, it leads to vasoconstriction and stimulates the secretion of aldosterone, which promotes sodium and water retention, increasing blood volume and, subsequently, blood pressure.

By inhibiting this conversion, ACE inhibitors reduce the levels of angiotensin II, resulting in vasodilation and decreased blood pressure. They also decrease aldosterone secretion, which leads to reduced sodium and water retention, further contributing to lower blood pressure and less strain on the heart.

This mechanism also plays a role in protecting kidney function, particularly in patients with hypertension and conditions such as diabetes mellitus, where kidney damage is a concern.

The other options provided involve mechanisms that are not directly associated with the action of ACE inhibitors. Inhibiting renin release pertains to a different class of drugs, blocking aldosterone receptor sites refers to the action of mineralocorticoid receptor antagonists, and increasing potassium secretion is not a feature of ACE inhibitors; rather, they can lead to increased potassium levels in the blood due to decreased aldosterone activity. Thus,