Changes in breath 13CO2/12CO2 during exercise of different intensities.
Changes in breath 13CO2/12CO2 during exercise of different intensities.
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不同强度运动时呼吸13CO2/12CO2的变化。
DOI：
10.1152/jappl.1996.81.3.1096
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发表时间：
1996
影响因子：
3.3
通讯作者：
P. Lefèbvre
中科院分区：
文献类型：
--
作者：
J. Gautier;F. Pirnay;M. Lacroix;F. Mosora;A. Scheen;G. Cathelineau;P. Lefèbvre
在运动过程中，通常使用呼吸13CO2/12CO2的测量来评估富含13C的外源性碳水化合物的氧化率。这项研究的目的是调查运动本身是否影响呼气二氧化碳中13C/12C的比率与运动强度的关系。用同位素操作质谱仪测定了呼气二氧化碳中~(13)C和~(12)C的相对丰度，用克雷格公式和校正标准表示为~(13)C(以%o为单位)。五名健康的年轻男性在夜间禁食后在跑步机上按随机顺序进行了四次105分钟的锻炼。工作速度大约是他们最大摄氧量(VO2max)的30%、45%、60%和75%。每15分钟或30分钟测定呼气二氧化碳增量13C和呼吸交换率(RER)。在30%和45%最大摄氧量时，30min时，Delta13C略有增加，但无统计学意义。相比之下，在6075%VO2max时，上升有统计学意义，平均分别为0.83和0.99%。平均13C增量(0~105min)随运动强度的增加而递增。个体Delta13C与RER呈正相关(r=0.653，P=0.002)，Delta13C与内源碳水化合物利用率呈正相关(r=0.752，P=0.001)。富含13C的外源性葡萄糖负荷(实际上未被摄入)的人为或“假氧化”是从呼气13C的变化中计算出来的。在整个运动期间，30%和40%最大摄氧量的变化没有统计学意义。然而，在前60分钟的运动中，外源性葡萄糖的这种假氧化在30%和45%的最大摄氧量时显著。总而言之，通过改变氧化内源底物的混合物，60%VO2max及以上的运动显著增加了呼气二氧化碳中13C/12C的比率。在这些强度下，这可能会导致高估口服13C标记底物的氧化程度。在较低的运动强度下，这种高估要小得多，并且主要影响在运动的最初部分记录的数值。
The measurement of breath 13CO2/12CO2 is commonly used during exercise to evaluate the oxidation rate of exogenous carbohydrates enriched in 13C. The aim of this study was to investigate whether exercise itself affects the 13C/12C ratio in expired air CO2 in relation to exercise intensity. The relative abundance of 13C and 12C in expired air CO2 was determined by isotoperatio mass spectrometry and expressed as delta 13C (in %o) by using Craig's formula and calibrated standards. Five healthy young men exercised on a treadmill after an overnight fast during > or = 105 min on four occasions and in a randomized order. Work rates were performed at approximately 30, 45, 60, and 75% of their maximal O2 uptake (VO2max). Delta 13C in expired air CO2 and respiratory exchange ratio (RER) were determined every 15 or 30 min during exercise. At 30 and 45% VO2max, a slight and not statistically significant increase in delta 13C was observed at 30 min. In contrast, at 60 75% VO2max, the rise was statistically significant and averaged 0.83 and 0.99%o, respectively. Average delta 13C (between 0 and 105 min) progressively increased with the intensity of exercise. Individual values of delta 13C and RER were positively correlated (r = 0.653, P = 0.002) as were values of delta 13C and endogenous carbohydrates utilized (r = 0.752, P < 0.001). Factitious or "pseudooxidation" of a 13C-enriched exogenous glucose load (indeed noningested) was calculated from the changes in expired air delta 13C. Over the whole period of exercise it was not statistically significant at 30 and 40% VO2max. However, over the first 60 min of exercise, such pseudooxidation of exogenous glucose was significant at 30 and 45% VO2max. In conclusion, by modifying the mix of endogenous substrates oxidized, exercise at 60% VO2max and above significantly increases the 13C/12C ratio in expired air CO2. At these intensities, this could lead to overestimation of the oxidation of 13C-labeled substrates given orally. At lower intensities of exercise, such overestimation is much smaller an affects mainly the values recorded during the initial part of the exercise bout.