Bicarbonate kinetics in humans: identification and validation of a three-compartment model.
Bicarbonate kinetics in humans: identification and validation of a three-compartment model.
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人体碳酸氢盐动力学：三室模型的识别和验证。
DOI：
10.1152/ajpendo.1995.269.1.e183
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Cobelli,C
中科院分区：
文献类型：
--
作者：
Saccomani,MP;Bonadonna,RC;Caveggion,E;DeFronzo,RA;Cobelli,C
碳酸氢盐动力学模型是一个正确的解释实验测量氧化在体内的碳标记的化合物是至关重要的。本研究的目的是开发一个房室模型的碳酸氢盐动力学在人类的示踪剂数据，特别注意模型识别和验证。数据库由9名正常受试者的14 C标记的碳酸氢盐的脉冲剂量研究组成。呼出气中CO2比活度（saRCO 2）衰减曲线的采样时间为4-7 h。此外，内源性生产的CO2，VCO 2，通过间接量热法测定。数据模型，即，一个指数模型，分析的衰减曲线的saRCO 2表明，首先，三个隔间是必要的，足以描述碳酸氢根示踪动力学。然后将房室模型用作系统模型。为了正确描述输入-输出配置，呼出空气中的标记CO2通量，phi RCO 2（= saRCO2.VCO2），已被用作示踪剂模型识别中的测量变量。研究了具有呼吸损失和非呼吸损失的乳头状三室模型。尽管有充分的证据表明呼吸损失发生在中央室，但非呼吸损失是否发生在中央室或两个外周室之一尚不确定。因此，考虑了三种竞争示踪剂模型。使用基于身体活动变量的数据的模型独立分析来计算系统中的平均停留时间，我们已经能够验证特定的模型结构，即，其中两个不可逆损失发生在中央隔室中。然后使用该经验证的示踪剂模型对系统中的碳酸氢盐质量进行定量。由于内源性生产进入系统的位置存在不确定性，因此推导出体内碳酸氢盐质量的下限和上限。
A model of bicarbonate kinetics is crucial to a correct interpretation of experiments for measuring oxidation in vivo of carbon-labeled compounds. The aim of this study is to develop a compartmental model of bicarbonate kinetics in humans from tracer data by devoting particular attention to model identification and validation. The data base consisted of impulse-dose studies of 14C-labeled bicarbonate in nine normal subjects. The decay curve of specific activity of CO2 in expired air (saRCO2) was frequently sampled for 4-7 h. In addition, endogenous production of CO2, VCO2, was measured by indirect calorimetry. A model of data, i.e., an exponential model, analysis of decay curves of saRCO2 showed first that three compartments are necessary and sufficient to describe bicarbonate tracer kinetics. Compartmental models were then used as models of system. To correctly describe the input-output configuration, labeled CO2 flux in the expired air, phi RCO2 (= saRCO2.VCO2), has been used as measurement variable in tracer model identification. A mammillary three-compartment model with a respiratory and a nonrespiratory loss has been studied. Whereas there is good evidence that respiratory loss takes place in the central compartment, whether nonrespiratory loss is taking place in the central compartment or in one of the two peripheral compartments is uncertain. Thus three competing tracer models were considered. Using a model-independent analysis of data, based on the body activity variable, to calculate mean residence time in the system, we have been able to validate a specific model structure, i.e., with the two irreversible losses taking place in the central compartment. This validated tracer model was then used to quantitate bicarbonate masses in the system. Because there is uncertainty about where endogenous production enters the system, lower and upper bounds of masses of bicarbonate in the body are derived.