What is the primary action of ACE inhibitors?

The primary action of ACE inhibitors is to block the conversion of angiotensin I to angiotensin II. This mechanism is crucial for their role in managing conditions such as hypertension and heart failure. Angiotensin II is a potent vasoconstrictor that raises blood pressure by narrowing blood vessels. It also stimulates the release of aldosterone, which leads to increased sodium and water reabsorption, further elevating blood pressure.

By inhibiting the enzyme ACE (angiotensin-converting enzyme), these medications reduce the levels of angiotensin II in the body, promoting vasodilation and decreasing blood pressure. This action not only helps in lowering the workload on the heart but also has beneficial effects on kidney function and reduces the risk of cardiovascular events.

The other options provided do not reflect the primary function of ACE inhibitors, as they do not increase heart rate, promote sodium reabsorption in the way diuretics do, nor do they enhance calcium entry into cells as seen in certain cardiovascular medications. Understanding this mechanism is essential for recognizing how ACE inhibitors fit into the broader context of pharmacological treatments for cardiovascular health.