Pallikarakis N, Sphiris N, Lefebvre P
Department of Medical Physics, University of Patras, Greece.
Eur J Appl Physiol Occup Physiol. 1991;63(3-4):179-83. doi: 10.1007/BF00233844.
In 13CO2 breath tests, based on 13C:12C ratio measurements, the appearance of 13C in exhaled CO2 was monitored after the administration of a 13C-labelled compound. Independently of the substrate used, the existence of a bicarbonate pool into which the CO2 produced enters before being exhaled, imposes a delay on the appearance of changes in the 13C:12C ratio. To estimate the nature and magnitude of this delay, we applied a two-compartment model to describe the kinetics of the body bicarbonate pool and we evaluated the 13C:12C ratio of CO2 entering that pool from the measured 13C:12C ratio in the exhaled CO2 after an oral intake of "naturally labelled" 13C-glucose. Our results demonstrated that discrepancies between total and exogenous glucose oxidation in relation to the peak occurrence time, as well as the absolute quantities, could be adequately explained by the interference of the bicarbonate stores.
在13CO2呼气试验中，基于13C:12C比率测量，在给予13C标记化合物后监测呼出CO2中13C的出现情况。无论使用何种底物，呼出前产生的CO2进入的碳酸氢盐池的存在，都会使13C:12C比率变化的出现产生延迟。为了估计这种延迟的性质和程度，我们应用了一个两室模型来描述体内碳酸氢盐池的动力学，并根据口服“天然标记”的13C-葡萄糖后呼出CO2中测得的13C:12C比率，评估进入该池的CO2的13C:12C比率。我们的结果表明，总葡萄糖氧化和外源性葡萄糖氧化在峰值出现时间以及绝对量方面的差异，可以通过碳酸氢盐储备的干扰得到充分解释。
