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Chylomicron remnant uptake by enterocytes is receptor dependent
1Department of Medicine, University of Tennessee, Memphis 38163, USA.
The American Journal of Physiology
|January 11, 1996
Summary
Enterocytes take up chylomicron remnants via a receptor-mediated process at their basolateral membranes. This uptake suggests remnants provide endogenous triacylglycerol fatty acids for enterocytes.
Area of Science:
- Lipid metabolism
- Cell biology
- Gastroenterology
Background:
- Dietary triacylglycerol absorption involves chylomicron formation and processing.
- Chylomicron remnants are enriched in endogenous fatty acids compared to parent chylomicrons.
Purpose of the Study:
- To investigate if enterocytes can uptake and metabolize chylomicron remnants.
- To determine if this uptake process is receptor-mediated.
Main Methods:
- Incubation of isolated enterocytes with 3H-labeled chylomicron remnants.
- Assessment of remnant uptake kinetics and localization (apical vs. basolateral).
- Competition assays using unlabeled remnants, LDL, and receptor inhibitors.
Main Results:
- Chylomicron remnants were taken up by the basolateral membrane of enterocytes, not the apical membrane.
- Uptake demonstrated saturation kinetics and was proportional to time and cell number.
- Uptake was inhibited by unlabeled remnants, LDL, and receptor inhibitors, indicating receptor mediation.
- Remnant uptake was highest in proximal intestinal villus tips.
Conclusions:
- Enterocytes mediate the uptake of chylomicron remnants via a receptor-dependent mechanism.
- This process occurs at the basolateral membrane, suggesting a role in endogenous fatty acid supply.