Regression of atherosclerosis in cholesterol-fed rabbits: Effects of fish oil and verapamil

Abstract

Previous studies have shown that either fish oil or verapamil can attenuate the development of atherosclerosis in the lipid-fed rabbit. The present study was designed to evaluate the individual and combined effects of these two interventions on regression.Seventy New Zealand rabbits in seven groups (10 each) were fed a 0.3% cholesterol diet for 10 weeks. Control group C10 was then killed. Control group C20 was fed a 0.3% cholesterol diet and the other five groups were fed a normal diet for an additional 10 weeks. Group F in three treated groups received 2 ml/day of fish oil (Proto-Chol, eicosapentaenoic acid, 180 mg/ml and docosahexaenoic acid, 120 mg/ml) by gavage. Group V received verapamil, 2 g/1,000 ml drinking water, and group FV received both fish oil and verapamil for an additional 10 weeks. Group CF (control for fish oil) received 2 ml/day of water by gavage and group CV (control for verapamil) received water without gavage for an additional 10 weeks.The percent of aortic and pulmonary atherosclerosis was measured by planimetry of sudanophilic lesions. The percent of aortic lesions in the four control groups (C20, C10, CF and CV) was 57 ± 22, 40 ± 15, 40 ± 14 and 33 ± 25%, respectively. The fish oil or verapamil groups (F, V, FV) showed a significant reduction in aortic lesions: 15 ± 17%, p < 0.05; 16 ± 12%, p < 0.05; and 26 ± 24%, p = NS, respectively. The area of pulmonary artery lesions was significantly higher in the control group (CF, 24 ± 9%) than in group F (11 ± 9%, p < 0.05), group V (12 ± 9%, p < 0.05) and group FV (17 ± 14%, p = NS).These data demonstrate that either fish oil or verapamil can decrease atherosclerosis in cholesterol-fed rabbits placed on a normal diet. However, there was no additive effect of fish oil and verapamil. Although not statistically significant, there was a suggestive antagonistic effect between fish oil and verapamil.