title: Modulation of whole body protein metabolism, during and after exercise, by variation of dietary protein.
abstract: The aim of this study was to investigate dietary protein-induced changes in whole body leucine turnover and oxidation and in skeletal muscle branched chain 2-oxo acid dehydrogenase (BCOADH) activity, at rest and during exercise. Postabsorptive subjects received a primed constant infusion of L-[1-13C,15N]leucine for 6 h, after previous consumption of a high- (HP; 1.8 g . kg-1 . day-1, n = 8) or a low-protein diet (LP; 0.7 g . kg-1 . day-1, n = 8) for 7 days. The subjects were studied at rest for 2 h, during 2-h exercise at 60% maximum oxygen consumption, then again for 2 h at rest. Exercise induced a doubling of both leucine oxidation from 20 micromol . kg-1 . h-1 and BCOADH percent activation from 7% in all subjects. Leucine oxidation was greater before (+46%) and during (+40%, P < 0.05) the first hour of exercise in subjects consuming the HP rather than the LP diet, but there was no additional change in muscle BCOADH activity. The results suggest that leucine oxidation was increased by previous ingestion of an HP diet, attributable to an increase in leucine availability rather than to a stimulation of the skeletal muscle BCOADH activity.
authors.affiliation: Department of Anatomy and Physiology, Small's Wynd, University of Dundee, Dundee, DD1 4HN, United Kingdom. J.L.Bowtell@lboro.ac.uk
authors.forename: J L
authors.initials: JL
authors.lastname: Bowtell
authors.forename: G P
authors.initials: GP
authors.lastname: Leese
authors.forename: K
authors.initials: K
authors.lastname: Smith
authors.forename: P W
authors.initials: PW
authors.lastname: Watt
authors.forename: A
authors.initials: A
authors.lastname: Nevill
authors.forename: O
authors.initials: O
authors.lastname: Rooyackers
authors.forename: A J
authors.initials: AJ
authors.lastname: Wagenmakers
authors.forename: M J
authors.initials: MJ
authors.lastname: Rennie
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000328:Adult; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007651:Keto Acids / Q000097:blood; D007658:Ketone Oxidoreductases / Q000378:metabolism; D007930:Leucine / Q000097:blood / Q000378:metabolism; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D011506:Proteins / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D007651:Keto Acids; D009097:Multienzyme Complexes; D011506:Proteins; C013082:alpha-ketoisocaproic acid; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D007930:Leucine; D009584:Nitrogen