In the present study we attempted to quantify the sequential changes occurring in cholesterolinduced aortic and coronary lesions in normotensive and renovascular hypertensive rabbits, which were placed on a 0.5% cholesterol diet for 16 weeks and observed up to 104 weeks after being withdrawn from the diet. After measuring the degree of surface involvement, a representative section covering the whole length of the aorta was obtained, and a histometric quantitative analysis was performed using an image-processing system. Furthermore, ten continuous step sections of the left coronary artery bed were prepared from each animal, and the degree of luminal stenosis was estimated in all the arterial segments contained. The results indicated a significant reduction of aortic lesions and a reversal of the luminal narrowing of the coronary artery in normotensive, as well as hypertensive, animals. It seems likely that, even in hypertensive animals, substantial regression of both aortic and coronary atherosclerosis can be expected after normalization of hypercholesterolemia.
