Dowd M K, Murali R, Seagrave R C
Iowa State University, Ames 50011.
Biophys J. 1991 Jul;60(1):160-71. doi: 10.1016/S0006-3495(91)82039-2.
An analysis of thermal effects on the facilitative transport of oxygen in skeletal muscle fibers is presented. Steady-state mass and energy transport balances are written and solved analytically or numerically using a finite-difference procedure. It is shown that no significant spatial thermal gradients exist due to internal reactions or bulk conduction effects across a muscle fiber. At typical muscle conditions, it is predicted that increased global temperature reduces the fraction of oxygenated myoglobin, increases local oxygen concentrations, and increases the percentage of oxygen flux attributed to oxy-myoglobin. The maximum supportable oxygen consumption rate, mO2max, is defined as the highest consumption rate sustainable without developing anoxic regions at the center of the fiber. By considering only temperature sensitive effects within fibers, mO2max is found to increase slightly with temperature at low temperatures. This increase is due to thermal effects on the diffusion coefficients as opposed to effects associated with the kinetics of the myoglobin-oxygen reaction. If the simulations include the temperature effect associated with oxygen solubility in blood plasma, mO2max decreases with temperature. A sensitivity analysis was performed by varying the values of relevant parameters. The maximum consumption rate was least affected by parameters associated with the kinetic and equilibrium constants and most affected by the diffusion coefficients and the concentration of myoglobin.
本文对热效应在骨骼肌纤维中促进氧气运输的情况进行了分析。通过稳态质量和能量传输平衡方程，采用有限差分法进行解析或数值求解。结果表明，由于肌肉纤维内部反应或整体传导效应，不存在显著的空间热梯度。在典型的肌肉条件下，预计整体温度升高会降低氧合肌红蛋白的比例，增加局部氧气浓度，并增加归因于氧合肌红蛋白的氧气通量百分比。最大可支持耗氧率(mO_2max)定义为在纤维中心不出现缺氧区域的情况下可持续的最高耗氧率。仅考虑纤维内的温度敏感效应时，发现低温下(mO_2max)随温度略有增加。这种增加是由于热对扩散系数的影响，而非与肌红蛋白 - 氧气反应动力学相关的影响。如果模拟包括与血浆中氧气溶解度相关的温度效应，(mO_2max)会随温度降低。通过改变相关参数的值进行了敏感性分析。最大耗氧率受与动力学和平衡常数相关的参数影响最小，受扩散系数和肌红蛋白浓度影响最大。
