Pharmacology of ACE inhibitors versus at₁ blockers

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 (AT₁) receptor blockers share a number of common properties, including their ability to lower blood pressure. However, they can be differentiated based on their individual effects on the renin-angiotensin system, the fibrinolytic system and the actions of bradykinin. They act at different points in the cascade of events that constitute the renin-angiotensin system. In animal models of atherosclerosis, ACE inhibition was associated with a significant reduction in the percentage surface area of lesions, while no similar effect was evident with AT₁ receptor blockade. In the fibrinolytic system, both ACE inhibition and AT₁ receptor blockade were associated with reduced aldosterone levels, although the effect was greater with ACE inhibition; only ACE inhibition was associated with a significant reduction in plasminogen activation inhibitor-1. By blocking the degradation of bradykinin, ACE inhibitors potentiate the ability of bradykinin to reduce blood pressure and stimulate the release of tissue-type plasminogen activator from the vasculature, an effect not seen with AT₁ receptor blockers.