Reduction of blood pressure and serum cholesterol levels is associated with reduced risk for the development of arteriosclerotic disease. Experimental studies indicate that reduced cholesterol levels result in arrest or regression of established diet-induced arterial lesions, but the effects of blood pressure reduction on such lesions are not clear. In order to investigate the effects of blood pressure on the regression of established lesions, we induced aortic intimal disease in cynomolgus monkeys by means of an artherogenic diet, produced midthoracic aortic coarctations, and restored the animals to low-cholesterol diets for 6 months. Diet control animals were neither coarctated nor restored to low-cholesterol diets. Animals with severe aortic stenosis and the regression diet had the same degree of abdominal aortic atherosclerosis and mural cholesterol content as diet control animals but esterified cholesterol and collagen content was elevated. Animals with mild coarctation and consuming the regression diet had significantly less abdominal aortic atherosclerosis than the diet control animals or the animals with severe coarctation. Although stenosis prevented the induction of lesions in previous experiments, the present study indicates that it did not reverse or delay progression of previously established lesions. The effect of pressure reduction on atherogenesis, even in the presence of reduced cholesterol levels, may depend on the extent and nature of the underlying lesions.
Animals Aorta