Response of glutamine metabolism to exogenous glutamine in
humans.
Hankard, R[acute]egis G., Dominique Darmaun, Brenda K. Sager, Debra
D'amore, W. Reed Parsons, Morey Haymond.
Nemours Children's Clinic, Jacksonville, Florida
APStracts 2:0107E, 1995.
To determine whether exogenous glutamine affects whole body glutamine
metabolism: 1) preliminary experiments were performed to verify that
L-[1-13C]-, L-[U-14C]-, and L-[3,4-3H]glutamine given simultaneously
by vein, provided similar estimates of glutamine appearance rates
(Ra), glutamine Ra (355+/-24, 373+/-19, and 393+/-24 [mu]mol.kg-1.h
-1; means+/-SE; NS), in 6 healthy men; glutamine oxidation accounted
for 32+/-3% and 51+/-5% (p<0.01) of glutamine Ra when measured
using L-[U-14C]-, and L-[1-13C]glutamine, respectively. 2) Five
volunteers received two 5-h intravenous infusions of L-[3,4
-3H]glutamine, and a simultaneous nasogastric infusion of L-[1
-13C]glutamine on two separate days in the postabsorptive state, along
with saline on one day, and natural L-glutamine (856+/-45 [mu]mol.kg
-1.h-1) on another day, in a randomized order. Splanchnic glutamine
extraction--determined from 13C-glutamine appearance into systemic
blood--reached 74+/-4% or 53+/-5% during the enteral infusion of
tracer alone or in combination with a large load of glutamine,
respectively. Glutamine infusion was associated with increased plasma
glutamine concentration (from 630+/-50 to 1297+/-75 [mu]M), Ra (from
258+/-20 to 589+/-45 [mu]mol.kg-1.h-1), and oxidation (from 179+/-20
to 477+/-47 [mu]mol.kg-1.h-1; all p<0.01), no change in glutamine
release from proteolysis; and a decline in glutamine de novo
synthesis (from 156+/-15 to 93+/-13 [mu]mol.kg-1.h-1). We conclude
that the response to exogenous glutamine includes: 1) a stimulation
of glutamine oxidation and splanchnic extraction; and 2) suppression
of glutamine de novo synthesis.
Received 19 January 1995; accepted in final form 10 May 1995.
APS Manuscript Number E23-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 26 May 1995.