Gut mucosal protein synthesis in fed and fasted humans..
Bouteloup-Demange, Corinne, Yves Boirie, Pierre Dechelotte, Pierre
Gachon, Bernard Beaufrere.
Laboratoire de Nutrition Humaine, Universite d'Auvergne, Centre de
Recherche en Nutrition Humaine, 63000 Clermont-Ferrand and GBPDN,
Centre Hospitalier Charles Nicolle, 76000 Rouen, France.
APStracts 4:0255E, 1997.
Fractional protein synthesis rate (FSR) of duodenal mucosa was
measured in two groups of six healthy young men, either in the fed
state at the end of a 10-day standardized diet or after a 36-h fast.
Protein synthesis rate was measured during a 9-h intravenous infusion
of 13C-leucine and 2H5-phenylalanine. The fed group also received an
intragastric tracer, 2H3-leucine, mixed with the liquid diet. At the
end of the tracer infusion, an endoscopy was performed to take
duodenal mucosal biopsies. The major results were: 1) duodenal
mucosal protein synthesis was high, 48.0 +/- 8.5%/d (mean +/- SE)
using the intravenous leucine tracer and the intracellular leucine
enrichment; 2) It was not affected by feeding whatever the tracer or
the precursor pool used for the calculations; 3) the two intravenous
tracers gave different FSR values; and 4) with the intragastric
tracer, FSR was 25%-220% of the rate calculated with the intravenous
tracer, depending on the precursor pool used for the calculation.
Thus, absolute values of FSR should be taken with caution, since they
depend on the precursor pool chosen, on the route of administration
of the tracer and of the tracer itself. However, gut mucosal protein
synthesis as assessed by an intravenous tracer is not affected by
feeding in humans.
Received 28 July 1997; accepted in final form 12 November 1997.
APS Manuscript Number E352-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 12 December 1997