Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation.
Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation.
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双标记水法：体内氧和氢同位素分馏。
DOI：
10.1152/ajpregu.1986.251.6.r1137
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Brown,C
中科院分区：
文献类型：
--
作者：
Schoeller,DA;Leitch,CA;Brown,C
双标记水法测量能量消耗的准确度和精密度受到蒸发失水和CO2排泄过程中同位素分馏的影响。为了表征体内同位素分馏，我们收集和同位素分析生理液体和气体。呼吸和经皮水蒸气同位素分馏。分馏程度表明，前者是在37 ℃的平衡控制下分馏，而后者是动力学分馏。汗液和尿液未分离。通过使用同位素平衡模型，通过分馏路线的水损失的分数估计从同位素丰度的身体水，当地饮用水，和膳食固体。分级水分损失平均为23%（SD = 10%）的水周转，这与我们以前的估计代谢率的基础上同意，但有一个系统的差异的结果基于O2和氢。当使用标记水测量水周转或CO2产生时，应校正呼吸和（非汗液）经皮损失中水分的同位素分馏。
The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO2 excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37 degrees C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O2 and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO2 production.