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Glutamine transport by basolateral plasma-membrane vesicles prepared from rabbit intestine
1Department of Biochemistry, J. Hillis Miller Health Center, University of Florida, Gainesville 32610.
The Biochemical Journal
|August 1, 1991
Summary
This study characterizes L-glutamine transport in rabbit intestinal cells. Findings reveal both Na(+)-dependent System A and Na(+)-independent System L carriers are crucial for nutrient uptake.
Area of Science:
- Cell Biology
- Molecular Biology
- Physiology
Background:
- L-Glutamine is a primary energy source for intestinal epithelial cells.
- It is absorbed from both intraluminal contents and arterial blood.
- Understanding basolateral membrane transport is key to enterocyte nutrition.
Purpose of the Study:
- To characterize L-glutamine transport mechanisms at the basolateral membrane of rabbit enterocytes.
- To identify the specific transporter systems involved in basolateral glutamine uptake.
Main Methods:
- Isolated basolateral membrane vesicles from rabbit intestinal epithelial cells were used.
- Transport assays were conducted to assess glutamine uptake kinetics.
- Inhibition studies with specific amino acid analogs (MeAIB, BCH) and pH variations were performed.
- System identification involved reciprocal inhibition analysis and substrate specificity tests.
Main Results:
- Basolateral glutamine transport is mediated by both Na(+)-dependent and Na(+)-independent carriers.
- Na(+)-dependent transport is attributed to System A, as evidenced by MeAIB inhibition and pH sensitivity.
- Na(+)-independent transport is attributed to System L, indicated by BCH inhibition and pH insensitivity.
Conclusions:
- Rabbit intestinal epithelial cells utilize System A for Na(+)-dependent basolateral glutamine uptake.
- System L facilitates Na(+)-independent glutamine transport across the basolateral membrane.
- These transporters are vital for maintaining enterocyte energy supply, especially in the post-absorptive state.