Comparative effects of ACE inhibitors and an angiotensin receptor blocker on atherosclerosis and vascular function.

Background: Both angiotensin-converting enzyme inhibitors (ACE-I(s)) and angiotensin receptor blockers (ARB(s)) provide vascular protection. This study was designed to compare ACE-I(s) with widely differing tissue affinity (captopril and quinapril) and an ARB (losartan) on vascular protection against the adverse effects of high cholesterol.

Results: Forty-two New Zealand rabbits on a 0.5% cholesterol diet were randomized into control, captopril (10 mg/kg/d), quinapril (0.3 mg/kg/d), and losartan (8 mg/kg/d) groups for 14 weeks. Captopril, quinapril, and losartan significantly attenuated aortic lipid lesions (P=0.001). Captopril and quinapril were more effective than losartan in preserving vascular relaxation.

Conclusions: Captopril, quinapril, and losartan had similar protective effects against atherogenesis. Captopril and quinapril were more effective than losartan in preserving vascular function. Increased bradykinin by ACE inhibition may be responsible for this improved vascular endothelial function.