Abstract
The thrombotic syndrome induced in the rat by a hyperlipemic diet containing laboratory chow, sodium cholate, butter and cholesterol was prevented by increasing the protein content of the diet, without affecting the cholesterolemia. With a purified diet, decreasing the protein level increased the cholesterolemic response; thrombosis could be produced under these conditions, provided that the dietary casein was decreased to approximately one-half of its normal level for the rat. With purified diets, the thrombi were located at various sites: 1) in small vessels; 2) in large coronary arteries with massive infarction ensuing; or 3) in the cardiac cavities. Aortic fatty streaks and even atherosclerotic plaques were consistently observed within 7 months with hyperlipemic purified diets, irrespective of the dietary level of protein. Although malignant hypertension increased the dietary-induced lipemia, as an additional factor it did not alter the thrombotic response of the rat to the protein level, but induced the formation of severe coronary atherosclerosis. Under our experimental conditions, hypercholesterolemia appears to be a prerequisite for both thrombosis and atherosclerosis, but the incidence or the severity of the lesions do not necessarily depend on the magnitude of the lipemic changes. The dietary level of protein appears to markedly influence the experimental production of thrombosis, atherosclerosis and hypertension in the rat, although not in the same direction.