Lai Nicola, Saidel Gerald M, Iorio Matthew, Cabrera Marco E
Department of Biomedical Engineering, Center for Modeling Integrated Metabolism Systems, Case Western Reserve University, Cleveland, OH 44106, USA.
Adv Exp Med Biol. 2009;645:155-60. doi: 10.1007/978-0-387-85998-9_24.
Muscle oxygenation measurements by near infrared spectroscopy (NIRS) are frequently obtained in humans to make inferences about mechanisms of metabolic control of respiration in working skeletal muscle. However, these measurements have technical limitations that can mislead the evaluation of tissue processes. In particular, NIRS measurements of working muscle represent oxygenation of a mix of fibers with heterogeneous activation, perfusion and architecture. Specifically, the relative volume distribution of capillaries, small arteries, and venules may affect NIRS data. To determine the effect of spatial volume distribution of components of working muscle on oxygen utilization dynamics and blood flow changes, a mathematical model of oxygen transport and utilization was developed. The model includes blood volume distribution within skeletal muscle and accounts for convective, diffusive, and reactive processes of oxygen transport and metabolism in working muscle. Inputs to the model are arterial O2 concentration, cardiac output and ATP demand. Model simulations were compared to exercise data from human subjects during a rest-to-work transition. Relationships between muscle oxygen consumption, blood flow, and the rate coefficient of capillary-tissue transport are analyzed. Blood volume distribution in muscle has noticeable effects on the optimal estimates of metabolic flux and blood flow in response to an exercise stimulus.
通过近红外光谱（NIRS）对肌肉氧合进行测量在人体中经常进行，以便推断工作骨骼肌中呼吸代谢控制的机制。然而，这些测量存在技术局限性，可能会误导对组织过程的评估。特别是，工作肌肉的NIRS测量代表了具有异质激活、灌注和结构的纤维混合物的氧合情况。具体而言，毛细血管、小动脉和小静脉的相对体积分布可能会影响NIRS数据。为了确定工作肌肉各组成部分的空间体积分布对氧利用动态和血流变化的影响，开发了一个氧运输和利用的数学模型。该模型包括骨骼肌内的血容量分布，并考虑了工作肌肉中氧运输和代谢的对流、扩散和反应过程。模型的输入参数是动脉血氧浓度、心输出量和ATP需求。将模型模拟结果与人类受试者在从休息到工作过渡期间的运动数据进行了比较。分析了肌肉耗氧量、血流量和毛细血管 - 组织运输速率系数之间的关系。肌肉中的血容量分布对运动刺激下代谢通量和血流量的最佳估计有显著影响。
