Cholesterol content as a possible determinant in the removal of chylomicron triglyceride by the liver

The nature of chylomicron removal from the circulation and the role of the liver in this process have been investigated by measuring the removal of chylomicron triglyceride and cholesterol from the plasma of normal and functionally hepatectomized rats. The rate of removal of chylomicron triglyceride exceeded that of both free and esterified cholesterol in all animals. Whereas chylomicrons were completely removed from the circulation of normal rats soon after intravenous injection, chylomicron remnant particles accumulated in the plasma very low density lipoprotein and chylomicron fractions of hepatectomized rats. The rate of removal of chylomicron triglyceride from the blood of the hepatectomized rats decreased when the cholesterol content of the chylomicrons was elevated. In addition, more chylomicron triglyceride remained in the circulation of the hepatectomized rats when the chylomicrons were enriched with cholesterol and the remnant particles derived from these chylomicrons were of lower average density. These observations indicate that the cholesteryl ester content of the chylomicrons influences the degree of triglyceride removal in extrahepatic tissue capillaries and thereby the amount of residual triglyceride in the remnant particles subsequently removed by the liver.