Chylomicrons lipolytic processing

Plasma VLDL is catabolized by LPL in the capillary beds in a process similar to the lipolytic processing of chylomicrons (Figure 35—1). When triglyceride hydrolysis is nearly complete, the VLDL remnants, usually termed intermediate-density lipoproteins (IDL), are released from the capillary endothelium and reenter the circulation. ApoB-100 containing small VLDL and IDL, which have a tj 2 minutes, have two potential fates 40-60% are cleared from the plasma... 

It is not until the vitamin E-containing chylomicrons reach the liver that discrimination between the various dietary vitamin E forms occurs. The hepatic a-TTP preferentially facilitates secretion of a-tocopherol, specifically 2R-a-tocopherols, and not other tocopherols or tocotrienols from the liver into the plasma in very low-density lipoproteins (VLDLs). In the circulation, VLDLs are cata-bolized to low-density lipoproteins (LDL are also known as the bad cholesterol because high LDL levels are associated with increased risk of heart disease). During this lipolytic process, all of the circulating lipoproteins become enriched with o-tocopherol. 

The best-known effect of APOE is the regulation of lipid metabolism (see Fig. 10.13). APOE is a constituent of TG-rich chylomicrons, VLDL particles and their remnants, and a subclass of HDL. In addition to its role in the transport of cholesterol and the metabolism of lipoprotein particles, APOE can be involved in many other physiological and pathological processes, including immunoregu-lation, nerve regeneration, activation of lipolytic enzymes (hepatic lipase, lipoprotein lipase, lecithin cholesterol acyltransferase), ligand for several cell receptors, neuronal homeostasis, and tissue repair (488,490). APOE is essential... 

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