Glycolysis is a source of pyruvate for transamination of glutamine
amino nitrogen in jejunal epithelial cells.
Cremin, John D., Jr., and Sharon E. Fleming.
Department of Nutritional Science, University of California,
Berkeley, CA 94720, U.S.A.
APStracts 3:0230G, 1996.
Previous research has shown that glucose increases transamination of
glutamine amino nitrogen with pyruvate. It is unclear whether glucose
or glutamine provides the pyruvate used for transamination. In the
current study, it was hypothesized that glucose provides pyruvate for
transamination of glutamine amino nitrogen. This hypothesis was
tested by tracing the metabolism of [2-13C]glucose in these cells
incubated in the presence of [2-13C]glucose or [2-13C]glucose and
glutamine using 13C-NMR. Glutamine supplementation increased alanine
production but did not affect lactate production. The [1-13C], [2
-13C], [3-13C], [1,2-13C], and [2,3- 13C] isotopomers of alanine and
lactate were produced when glutamine was supplemented. Glutamine
supplementation increased production of [2-13C], [1,2-13C], and [2,3
-13C] isotopomers of alanine, but did not affect the production of
isotopomers of lactate. The ratio of production of [2-13C]alanine :
[3-13C]alanine was 37:1 when glutamine was present. The predominance
of production of [2-13C]alanine versus all other isotopomers
demonstrates that a large proportion of the pyruvate used for
transamination of glutamine amino nitrogen was derived from
glycolysis.
Received 3 July 1996; accepted in final form 28 September 1996.
APS Manuscript Number G269-6.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996