Atherosclerosis in the aorta of hypercholesterolemic rabbits and the influence of daltroban.

These studies have examined aortic atherogenesis in cholesterol-fed rabbits and have correlated the effects of daltroban to the pathomechanism of the vessel wall lesions. After feeding a 0.5% cholesterol-enriched diet for 96 d atherosclerotic alterations were seen, which exhibited a proximo-distal pattern, to which the branching of the aorta contributed considerably. Depending on their localization and size a varying cellular constitution of the plaques was obvious. Large plaques, which were mainly seen in the aortic arch and the proximal descending thoracic aorta, consisted of numerous proliferating cells, masses of fibrillar ground substance, clusters of foam cells, and rarely contained cholesterol crystals and necroses. Emerging plaques mainly found in distal thoracic and abdominal aorta imposed as fatty streaks. Daltroban treatment, used in a clinically relevant doses of 10 mg/kg b. wt. per day, reduced extension and protrusional area of plaques to about 40%, which was evaluated using a newly developed computerized morphormetric method, in association with significant reductions in free cholesterol content within the aorta. The results suggest that daltroban inhibits the progression of atherosclerosis in cholesterol-fed rabbits. This effect may be related to its antagonistic interaction with the thromboxane A2 receptor and also to an inhibition of the cholesterol metabolism.