Effect of Na/sup +/ replacement on transport and metabolism of succinate and glutamine in jejunal epithelium
Novel radioisotope techniques may be applied to the analysis of metabolism and transport in intact cells. In the present study, rat jejunal epithelium was suspended in media containing five concentrations of glutamine between 0 and 5 mM, either Na/sup +/ or N-methyl-D-glucamine (NMDG/sup +/) as the major cation, and 44 ..mu..M (/sup 14/C)succinate. An increased ratio of steady state /sup 14/CO/sub 2/ production from (1,4-/sup 14/C)succinate versus (2,3-/sup 14/C)succinate indicates enhanced efflux of TCA cycle intermediates to products other than CO/sub 2/, relative to cycle flux. Glutamine dependent increases in succinate CO/sub 2/ ratios plateaued above 0.5mM glutamine, indicating that entry of glutamine-derived carbon into TCA cycle intermediate pools was saturated above physiological plasma glutamine concentrations. Although /sup 14/CO/sub 2/ production from succinate tracers was reduced approximately 95% by Na/sup +/ replacement, succinate CO/sub 2/ ratios were not altered, indicating that succinate uptake was significantly reduced in NMDG/sup +/ medium. /sup 14/C-alanine and /sup 14/C-aspartate accumulation increased with increasing glutamine concentrations in a pattern similar to succinate CO/sub 2/ ratios, indicating that these amino acids were net products of glutamine carbon. Incorporation of /sup 14/C into lactate and alanine demonstrated the presence of an enzymatic pathway for conversion of TCA cycle intermediates to pyruvate.
- Research Organization:
- George Washington Univ. Medical Center, Washington, DC
- OSTI ID:
- 5392529
- Report Number(s):
- CONF-8604222-; TRN: 86-028404
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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GLUTAMINE
MEMBRANE TRANSPORT
METABOLISM
SODIUM COMPOUNDS
BIOLOGICAL EFFECTS
SUCCINIC ACID
ALANINES
ASPARTIC ACID
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CARBON DIOXIDE
CATIONS
EPITHELIUM
RATS
SMALL INTESTINE
TRACER TECHNIQUES
ALKALI METAL COMPOUNDS
AMIDES
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BODY
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHARGED PARTICLES
DICARBOXYLIC ACIDS
DIGESTIVE SYSTEM
GASTROINTESTINAL TRACT
INTESTINES
IONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXIDES
OXYGEN COMPOUNDS
RODENTS
TISSUES
VERTEBRATES
550501* - Metabolism- Tracer Techniques