Chylomicron remnant uptake by enterocytes is receptor dependent. Soued, Mounzer, and Charles M. Mansbach, Ii. Department of Medicine, Division of Gastroenterology, The University of Tennessee, Memphis, Memphis, TN 38163 and The Veterans Administration Medical Center, Memphis, TN 38104
APStracts 2:0156G, 1995.
During glyceryltrioleate absorption in the rat, mucosal triacylglycerol-fatty acids have been shown to consist of only 71 % exogenous oleate. Chylomicron remnants are enriched with endogenous triacylglycerol-fatty acids as compared to their parent chylomicrons which consist primarily of exogenous ones. Since enterocytes have the apolipoprotein B100/E receptor, this study was directed at determining if the cells can take up and metabolize chylomicron remnants and, if so, whether this was receptor mediated. Isolated enterocytes were incubated with purified 3H- chylomicron remnants. The remnants were shown to be taken up by the basolateral membrane, not the apical membrane. Remnant uptake was proportional to time, number of enterocytes, and saturation kinetics were observed. Non -radiolabeled remnants, human LDL, anti-LDL receptor antibody, and receptor associated protein, an LDL related receptor inhibitor, were all shown to compete for or reduce 3H-remnant uptake. Remnants taken up by the enterocytes could not be removed on incubation with excess human LDL. Uptake was shown to be greatest in the villus tips of the proximal intestine. These studies suggest that enterocytes take up chylomicron remnants by a receptor mediated process from their basolateral membranes and that the remnants could provide a source of endogenous triacylglycerol-fatty acids for the enterocytes. 

Received 28 February 1995; accepted in final form 26 July 1995.
APS Manuscript Number G87-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.