Verapamil and diet halt progression of atherosclerosis in cholesterol fed rabbits.

The present study was designed to evaluate the effects of oral verapamil and normal diet on regression of atherosclerotic plaque in cholesterol fed rabbits. Forty-three rabbits were separated into 6 groups and studied for 24 weeks. All groups had a cholesterol diet for the first 12 weeks. Group I was then sacrificed and had 38 +/- 23% (mean +/- standard deviation) aortic plaque. During weeks 13 to 24, group II (cholesterol diet) and group III (normal diet) had similar percentages of aortic plaque: 80 +/- 7% and 78 +/- 22%, respectively. Group IV (cholesterol diet), was treated with oral verapamil for 24 weeks and had significantly less plaque (54 +/- 10%) than group II, (80 +/- 7%). In group V (cholesterol diet), treatment with oral verapamil during weeks 13 to 24 did not significantly reduce plaque (70 +/- 23%), compared to group II, (80 +/- 7%). In group VI, normal diet and verapamil during weeks 13 to 24 significantly reduced aortic plaque (46 +/- 25) when compared to group II (80 +/- 7%). Group VI (46%) did not differ from group I (38%). It is concluded that verapamil combined with a normalized diet can halt the progression of aortic atherosclerosis after a 12 week atherogenic diet in rabbits. Verapamil or diet alone was ineffective in the second 12 weeks. Overall, verapamil was effective in preventing atherosclerosis but was ineffective in causing regression of atherosclerosis.