What is the main mechanism of action of ACE inhibitors and ARBs?

The main mechanism of action of ACE inhibitors and ARBs (Angiotensin Receptor Blockers) is their role in inhibiting the RAAS (Renin-Angiotensin-Aldosterone System) activation. ACE inhibitors work by blocking the angiotensin-converting enzyme, which is responsible for converting angiotensin I to angiotensin II—this potent vasoconstrictor raises blood pressure. By inhibiting this conversion, ACE inhibitors decrease levels of angiotensin II, leading to vasodilation, reduced blood pressure, and decreased workload on the heart.

ARBs also function by blocking the action of angiotensin II on its receptors, preventing vasoconstriction and aldosterone secretion, which further reduces blood pressure.

The result of both classes of medications is a decrease in fluid retention and a reduction in blood pressure through the suppression of the RAAS, making them effective in managing conditions such as hypertension and heart failure. This mechanism is crucial for mitigating the complications associated with high blood pressure.

In contrast, the options that involve activation of the RAAS or increased sodium retention do not align with the pharmacological effects of ACE inhibitors and ARBs, which aim specifically to inhibit this system and promote sodium excretion.