Simultaneous blood-tissue exchange of oxygen, carbon dioxide, bicarbonate, and hydrogen ion
Simultaneous blood-tissue exchange of oxygen, carbon dioxide, bicarbonate, and hydrogen ion
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DOI：
10.1007/s10439-005-9066-4
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发表时间：
2006-07-01
影响因子：
3.8
通讯作者：
Bassingthwaighte, James B.
中科院分区：
文献类型：
--
作者：
Dash, Ranjan K.;Bassingthwaighte, James B.
建立了一个详细的非线性四区（红细胞、血浆、间质液和实质细胞）轴向分布的对流-扩散-渗透-反应-结合计算模型，研究了氧（O-2）和二氧化碳（CO2）在心脏血液组织交换系统中的同时传输和交换.由于血液和组织中的pH变化影响O-2和CO2的运输和交换（玻尔和哈勒效应），并且由于大多数CO2通过CO2水合（缓冲）反应以HCO 3-（碳酸氢盐）形式运输，因此HCO 3-和H+的运输和交换也与O-2和CO2的运输和交换一起沿着。此外，该模型考虑了O-2和CO2与红细胞内血红蛋白的竞争性非线性结合（非线性O-2 - CO2相互作用，Bohr和Halfenic效应），以及肌红蛋白促进的实质细胞内O-2的运输。实质细胞内通过细胞色素-c氧化酶反应消耗O-2是基于米氏动力学。相应的二氧化碳产生量由呼吸商（RQ）决定，取决于碳水化合物、蛋白质和脂肪的相对消耗。该模型给出了一个生理上现实的描述O-2运输和代谢的心脏微循环。此外，由于示踪剂瞬态和稳态的模型解可以高效地计算，该模型可能是常规数据分析的首选工具，其中需要重复的解决方案和参数优化，如PET成像中用于估计心肌O-2消耗的情况。
A detailed nonlinear four-region (red blood cell, plasma, interstitial fluid, and parenchymal cell) axially distributed convection-diffusion-permeation-reaction-binding computational model is developed to study the simultaneous transport and exchange of oxygen (O-2) and carbon dioxide (CO2) in the blood tissue exchange system of the heart. Since the pH variation in blood and tissue influences the transport and exchange of O-2 and CO2 (Bohr and Haldane effects), and since most CO2 is transported as HCO3- (bicarbonate) via the CO2 hydration (buffering) reaction, the transport and exchange of HCO3- and H+ are also simulated along with that of O-2 and CO2. Furthermore, the model accounts for the competitive nonlinear binding of O-2 and CO2 with the hemoglobin inside the red blood cells (nonlinear O-2 - CO2 interactions, Bohr and Haldane effects), and myoglobin-facilitated transport of O-2 inside the parenchymal cells. The consumption of O-2 through cytochrome-c oxidase reaction inside the parenchymal cells is based on Michaelis - Menten kinetics. The corresponding production of CO2 is determined by respiratory quotient (RQ), depending on the relative consumption of carbohydrate, protein, and fat. The model gives a physiologically realistic description of O-2 transport and metabolism in the microcirculation of the heart. Furthermore, because model solutions for tracer transients and steady states can be computed highly efficiently, this model may be the preferred vehicle for routine data analysis where repetitive solutions and parameter optimization are required, as is the case in PET imaging for estimating myocardial O-2 consumption.