Reference : Endogenous substrate oxidation during exercise and variations in breath 13CO2/12CO2.
Scientific journals : Article
Human health sciences : Endocrinology, metabolism & nutrition
http://hdl.handle.net/2268/14022
Endogenous substrate oxidation during exercise and variations in breath 13CO2/12CO2.
English
Gautier, J. F. [> > > >]
Pirnay, Freddy mailto [Centre Hospitalier Universitaire de Liège - CHU > > Pneumologie-Allergologie >]
Jandrain, Bernard mailto [Centre Hospitalier Universitaire de Liège - CHU > > Diabétologie,nutrition, maladies métaboliques >]
Lacroix, M. [> > > >]
Mosora, F. [> > > >]
Scheen, André mailto [Université de Liège - ULg > Département des sciences cliniques > Diabétologie, nutrition et maladie métaboliques - Médecine interne générale >]
Lefebvre, Pierre [Centre Hospitalier Universitaire de Liège - CHU > > Diabétologie,nutrition, maladies métaboliques >]
1993
Journal of Applied Physiology (Bethesda, Md. : 1985)
American Physiological Society
74
1
133-8
Yes (verified by ORBi)
8750-7587
1522-1601
Bethesda
MD
[en] Adult ; Breath Tests ; Calorimetry ; Carbon Dioxide/metabolism ; Carbon Isotopes ; Energy Metabolism/physiology ; Exercise/physiology ; Humans ; Male ; Mass Spectrometry ; Oxidation-Reduction
[en] This study attempted to induce a major shift in the utilization of endogenous substrates during exercise in men by the use of a potent inhibitor of adipose tissue lipolysis, Acipimox, and to see to what extent this affects the 13C/12C ratio in expired air CO2. Six healthy volunteers exercised for 3 h on a treadmill at approximately 45% of their maximum O2 uptake, 75 min after having ingested either a placebo or 250 mg Acipimox. The rise in plasma free fatty acids and glycerol was almost totally prevented by Acipimox, and no significant rise in the utilization of lipids, evaluated by indirect calorimetry, was observed. Total carbohydrate oxidation averaged 128 +/- 17 (placebo) and 182 +/- 21 g/3 h (Acipimox). Conversely, total lipid oxidation was 84 +/- 5 (placebo) and 57 +/- 6 g/3 h (Acipimox; P < 0.01). Under placebo, changes in expired air CO2 delta 13C were minimal, with only a 0.49/1000 significant rise at 30 min. In contrast, under Acipimox, the rise in expired air CO2 delta 13C averaged 1/1000 and was significant throughout the 3-h exercise bout; in these conditions calculation of a "pseudooxidation" of an exogenous sugar naturally or artificially enriched in 13C, but not ingested, would have given an erroneous value of 19.8 +/- 2.6 g/3 h. Thus under conditions of extreme changes in endogenous substrate utilization, an appropriate control experiment is mandatory when studying exogenous substrate oxidation by 13C-labeled substrates and isotope-ratio mass spectrometry measurements on expired air CO2.
http://hdl.handle.net/2268/14022

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