EFFECT OF DURATION OF CHOLESTEROL FEEDING ON DEVELOPMENT OF SUDANOPHILIC LESIONS IN RABBIT AORTA

Polar coordinate mapping was used to determine the rate of growth of fibrous plaques and accompanying atherosclerotic sudanophilic lesions on the aortic wall around several major branches of the aortae of cholesterol fed [albino] rabbits; 4 groups, with 6-8 mo. old males in each, were used in the study. One group served as a control and the remaining 3 were fed a diet of 2% cholesterol and 6% heated corn oil mixed with ground rabbit pellets for 4, 8 and 10 wk each. Animals were sacrificed, the aortae removed, stained with Sudan III, pinned at in vivo dimensions and mapped by the polar coordinate method. No sudanophilic lesions were observed in the control animals. In the experimental groups, the early lesions, except the coronaries, were almost entirely distal to the orifices and maintained roughly the same contour while spreading around the orifice. The coronary lesions completely encircled the orifices. As lesions progressed they became elevated and often granular, so that the lesions themselves may have affected flow profiles around the orifices. Lesions around adjacent orifices were fused in 48% of the cases after 10 wk on the diet, as opposed to 2% after 4 wk on the diet. More prolonged experiments were not possible with this diet as the animals developed jaundice and diarrhea. Hemodynamically, early sudanophilic lesions in cholesterol-fed rabbits develop on the aortic wall in areas of high shear stress.