Preservation of Endogenous Antioxidant Activity and Inhibition of Lipid Peroxidation as Common Mechanisms of Antiatherosclerotic Effects of Vitamin E, Lovastatin and Amlodipine

Objectives. We sought to document the common mechanisms of the antiatherogenic effects of the cholesterol-lowering hydroxymethylglutaryl coenzyme (HMG-CoA) reductase inhibitor lovastatin, the dihydropyridine Ca2+ blocker amlodipine and the antioxidant vitamin E. Background. Vitamin E, HMG-Co reductase inhibitors and Ca2+ blockers each inhibit atherosclerosis in hypercholesterolemic animals. Methods. New Zealand White rabbits were fed regular chow (Group A), chow with 1% cholesterol (Group B), 1% cholesterol diet plus lovastatin (Group C), 1% cholesterol diet plus vitamin E (Group D) or 1% cholesterol diet plus amlodipine (Group E) for 12 weeks. The extent of aortic atherosclerosis was measured by planimetry of the sudanophilic area. Malondialdehyde (MDA) and superoxide dismutase (SOD) in blood were measured as indexes of lipid peroxidation and antioxidant activity, respectively. Results. Group rabbits showed no atherosclerosis, whereas Group B rabbits had 17.4 ± 9.3% (mean ± SD) of the aort covered with atherosclerosis, and Groups C, D and E rabbits had significantly less atherosclerosis. Plasm SOD activity was lower in Group B than in Group (6.9 ± 1.1 vs. 12.8 ± 1.5 U/ml, p < 0.01) and was preserved in the groups given lovastatin, vitamin E or amlodipine with high cholesterol diet. The serum MD level was higher in Group B rabbits than Group rabbits (12.1 ± 2.6 vs. 1.2 ± 0.1 nmol/ml, p < 0.01) and increased minimally in rabbits given lovastatin, vitamin E or amlodipine with high cholesterol diet. In in vitro experiments, both lovastatin and amlodipine preserved SOD activity and reduced the oxidizability of low density lipoproteins by rabbit leukocytes. Conclusions. This study suggests that reduction in lipid peroxidation and preservation of SOD may be common mechanisms of antiatherosclerotic effects of lovastatin, vitamin E and amlodipine.