Regulation of fatty acid synthesis in isolated hepatocytes by intestinal chylomicrons and their remnants

Abstract

Dietary fatty acids are incorporated into chylomicrons and the chylomicron triglycerides are degraded by the action of lipoprotein lipase. The resultant particles, remnants, are selectively metabolized by the liver [ 11. Sherrill and Dietschy demonstrated that unmetabolized chylomicrons were taken up at very low rates, whereas chylomicron remnants were taken up by the perfused liver at much higher velocities [2]. Recently, Carrella and Cooper demonstrated that there was a high affinity receptor for the chylomicron remnant on the surface of the hepatocytes [3]. This study was undertaken to examine the effects of chylomicrons and their remnants on the fatty acid synthesis in isolated rat hepatocytes. Chylomicrons in the medium containing postheparin rat plasma significantly inhibited fatty acid synthesis in hepatocytes. On the other hand, chylomicrons in the medium containing pre-heparin rat plasma caused inhibition to a much smaller extent. Remnants prepared from the chylomicrons injected into functionally hepatectomized rats inhibited fatty acid synthesis to a greater extent than unmetabolized chylomicrons. Thus the chylomicron remnants produced by the action of lipoprotein lipase may play an important role in the regulation of hepatic fatty acid synthesis.