Hepatic origin of cholesteryl oleate in coronary artery atherosclerosis in African green monkeys. Enrichment by dietary monounsaturated fat

Abstract

Relationships among plasma lipoprotein cholesterol, cholesterol secretion by the isolated, perfused liver, and coronary artery atherosclerosis were examined in African green monkeys fed diets containing cholesterol and 35% of calories as fat enriched in polyunsaturated, monounsaturated, or saturated fatty acids. The livers of animals fed monounsaturated fat had significantly higher cholesteryl ester concentrations (8.5 mg/g wet wt) than the livers of the other diet groups (3.65 and 3.37 mg/g wet wt for saturated and polyunsaturated fat groups, respectively) and this concentration was highly correlated with plasma cholesterol and apoB concentrations in each diet group. Cholesteryl oleate was 58 and 74. 5% of the liver cholesteryl ester in the saturated and monounsaturated fat groups. In each diet group, perfusate cholesteryl ester accumulation rate was highly correlated to liver and plasma cholesterol concentrations, and to plasma LDL cholesteryl ester content. Cholesteryl oleate was 48 and 67% of the cholesteryl esters that accumulated in perfusate in the saturated and monounsaturated fat animals, and this percentage was very highly correlated (r = -0.9) with plasma apoB concentration. Finally, in these two diet groups, liver perfusate cholesteryl ester accumulation rate was well correlated (r >/= 0.8) to coronary artery cholesteryl ester concentration, a measure of the extent of coronary artery atherosclerosis that occurred over the five years of diet induction in these animals. These data define an important role for the liver in the cholesteryl oleate enrichment of the plasma lipoproteins in the saturated and monounsaturated fat groups, and demonstrate strong relationships among hepatic cholesteryl ester concentration, cholesteryl ester secretion, and LDL particle cholesteryl ester content. The high correlation between liver cholesteryl ester secretion and coronary artery atherosclerosis provides the first direct demonstration of the high degree of importance of hepatic cholesteryl ester secretion in the development of this disease process. The remarkable degree of enrichment of cholesteryl oleate in plasma cholesteryl esters of the monounsaturated fat group may account for the relatively high amount of coronary artery atherosclerosis in this group.