Recovery of13CO2during rest and exercise after [1-13C]acetate, [2-13C]acetate, and NaH13CO3infusions

• DOI: 10.1152/ajpendo.2001.281.4.e683
• Publication Date: 2017-12-22T14:44:53Z
• Authors: Jeff K. Trimmer; Gretchen A. Casazza; Michael A. Horning; George A. Brooks
• Keywords: Bicarbonate

For estimating the oxidation rates (Rox) of glucose and other substrates by use 13 C-labeled tracers, we obtained correction factors to account for label dilution in endogenous bicarbonate pools TCA cycle exchange reactions. Fractional recoveries C respiratory gases were determined during 225 min rest 90 leg ergometry at 45 65% peak oxygen uptake (V˙o 2 ) after continuous infusions [1- C]acetate, [2- or NaH CO 3 . In parallel trials, [6,6- H]glucose C]glucose given. Experiments conducted an overnight fast with exercise commencing 12 h last meal. During transition from exercise, production increased ( P < 0.05) intensity-dependent manner. Significant differences observed fractional as (NaH , 77.5 ± 2.8%; 49.8 2.4%; 26.1 1.4%). compared rest. Magnitudes both intensities tracer specific 93%; 80%; 65%). Use acetate-derived factor resulted Rox values excess P< rate disappearance hard exercise. We conclude that, fast: 1) recovery [ C]acetate is decreased bicarbonate; 2) position acetate affects carbon estimations; 3) increases isotope-dependent manner; 4) application measurements results V˙o Therefore, bicarbonate, not acetate, are advocated tracers exercising men.