GLYCOLYSIS IS A SOURCE OF PYRUVATE FOR TRANSAMINATION OF GLUTAMINE AMINO NITROGEN IN JEJUNAL EPITHELIAL-CELLS

Previous research has shown that glucose increases transamination of g lutamine amino nitrogen with pyruvate. It is unclear whether glucose o r glutamine provides the pyruvate used for transamination. In the curr ent study, it was hypothesized that glucose provides pyruvate for tran samination of glutamine amino nitrogen. This hypothesis was tested by tracing the metabolism of [2-C-13]glucose in these cells incubated in the presence of [2-C-13]glucose or [2-C-13]glucose and glutamine using C-13 nuclear magnetic resonance. Glutamine supplementation increased alanine production but did not affect lactate production. The 1-C-13, 2-C-13, 3-C-13, 1,2-C-13, and 2,3-C-13 isotopomers of alanine and lact ate were produced when glutamine was supplemented. Glutamine supplemen tation increased production of 2-C-13, 1,2-C-13, and 2,3-C-13 isotopom ers of alanine but did not affect the production of isotopomers of lac tate. The ratio of production of [2-C-13] alanine to [3-C-13] alanine was 37:1 when glutamine was present. The predominance of production of [2-C-13]alanine vs. all other isotopomers demonstrates that a large p roportion of the pyruvate used for transamination of glutamine amino n itrogen was derived from glycolysis.