Acute post-prandial changes in leucine metabolism as assessed with
an intrinsically labelled milk protein.
Boirie, Yves, Pierre Gachon, Sandrine Corny, Jacques Fauquant, Jean
-Louis Maubois, Bernard Beaufr[grave]ere.
Laboratoire de Nutrition Humaine, Universit[acute]e Clermont
Auvergne, CRNH, Clermont-Ferrand; Pharmacie Centre Hospitalier
R[acute]egional, Clermont-Ferrand; Laboratoire de Technologie
Laiti[grave]ere, INRA, Rennes, France
APStracts 3:0163E, 1996.
Mechanisms of protein gain during protein feeding have been
investigated using a combination of oral and intravenous labelled
leucine in healthy young men. The oral labelled leucine was
administered, either as a free oral tracer (13C- or 2H3-leucine)
added to unlabelled whey protein, or as whey protein intrinsically
labelled with L-[1-13C] leucine. When the oral tracer was free
leucine, it appeared in the plasma more rapidly than the unlabelled
leucine derived from the whey protein, and this resulted in an
artefactual 88 % decrease of protein breakdown. When the oral tracer
was protein bound, protein breakdown did not change significantly
after the meal. By contrast, non oxidative leucine disposal (i.e.,
protein synthesis) was stimulated by 63 % by the meal. In conclusion
1) an intrinsically labelled protein is more appropriate than an oral
free tracer to study post-prandial leucine kinetics under non-steady
state conditions, 2) protein gain after a single whey protein meal
solely results from an increased protein synthesis with no
modification of protein breakdown.
Received 28 March 1996; accepted in final form 25 July 1996.
APS Manuscript Number E157-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996