Which agents primarily block the action of angiotensin II?

ACE inhibitors are designed to specifically target the renin-angiotensin-aldosterone system (RAAS), particularly the action of angiotensin II, which is a potent vasoconstrictor contributing to increased blood pressure. By inhibiting the enzyme that converts angiotensin I to angiotensin II, these agents effectively reduce levels of angiotensin II in the body. This leads to vasodilation, decreased secretion of aldosterone (which normally promotes sodium and water retention), and ultimately lowers blood pressure.

In contrast, other classes of antihypertensive agents have different mechanisms of action. Beta-blockers primarily lower blood pressure by decreasing heart rate and contractility, thus reducing cardiac output. Calcium channel blockers work by preventing calcium from entering heart and blood vessel cells, leading to relaxation of the vascular smooth muscle, which lowers blood pressure. Diuretics work by increasing urinary excretion of sodium and water, which reduces blood volume and subsequently blood pressure. While all these medications can be effective in managing hypertension, ACE inhibitors specifically block the action of angiotensin II, making them a distinct therapeutic class for this purpose.