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Glutamine oxidation and utilization by rat and human oesophagus and duodenum
L A James1, P G Lunn, S Middleton
1MRC Dunn Clinical Nutrition Centre, Cambridge, UK.
The British Journal of Nutrition
|September 22, 2000
Summary
Glutamine is a preferred fuel for duodenal tissue but not esophageal tissue in rats and humans. This difference in fuel utilization suggests distinct responses to glutamine administration in these tissues.
Area of Science:
- Gastroenterology
- Metabolism
- Cell Biology
Background:
- Glutamine and glucose are vital substrates for gastrointestinal tissue metabolism.
- Understanding the differential utilization of these fuels is crucial for comprehending tissue-specific metabolic adaptations.
Purpose of the Study:
- To investigate and compare the utilization and oxidation rates of glutamine and glucose in esophageal and duodenal tissues.
- To determine the contribution of glutamine to the oxidative metabolism of these tissues in rats and humans.
Main Methods:
- Comparative analysis of glutamine and glucose uptake and oxidation in isolated rat and human esophageal and duodenal tissues.
- Measurement of CO2 production from labeled glutamine (glutamine-C) and glucose.
- Assessment of glutamine's metabolic fate, including conversion to glutamate and alanine.
Main Results:
- Esophageal tissue showed significantly lower glutamine utilization and oxidation compared to duodenal tissue in rats.
- Duodenal tissue derived approximately 34% of its CO2 production from glutamine, a contribution not suppressed by glucose.
- Human biopsy data mirrored rat findings, with glutamine oxidation contributing significantly to duodenal (34%) but minimally to esophageal (8%) CO2 production.
Conclusions:
- Glutamine serves as a primary fuel source for duodenal tissue, while it is not a preferred substrate for esophageal tissue.
- The distinct metabolic profiles of esophageal and duodenal tissues indicate differential responses to glutamine availability and administration.