Lagerlund T D, Low P A
Department of Neurology, Mayo Foundation, Rochester, Minnesota 55905.
Microvasc Res. 1987 Sep;34(2):211-22. doi: 10.1016/0026-2862(87)90054-9.
We have performed a mathematical simulation on a CYBER computer of the release, diffusion, and consumption of oxygen in the capillaries and surrounding tissue of peripheral nerve under steady-state conditions. The Krogh-Erlang equation was used to calculate oxygen tension in tissue, while numerical solution of the differential equation governing oxygen release from hemoglobin and diffusion was used to calculate oxygen tension in the capillary. Using average measured values for the parameters of oxygen solubility, diffusion coefficient, capillary diameter, capillary density, nerve blood flow, oxygen consumption rate, and arterial oxygen tension in rat peripheral nerve, we calculated the endoneurial oxygen tension as a function of distance from the nearest capillary and distance along the capillary from the arterial end to the venous end. The range of calculated values agreed with experimental measurements obtained from the sciatic nerves of rats. Alterations in these parameters produced changes in the calculated oxygen tension distributions. Conditions which adversely affected oxygen delivery include reduced capillary diameter, increased intercapillary distance, reduced blood flow, and reduced arterial oxygen tension. The lower experimentally obtained oxygen tensions in sciatic nerves of diabetic rats could be accounted for reasonably by this model on the basis of a 33% reduction in nerve blood flow (consistent with previously measured flow reduction). However, the measured reduction in oxygen tensions in sciatic nerves of rats with experimental galactose neuropathy were not as marked as those predicted on the basis of a 22% increase in tissue cylinder radius in the model (consistent with experimental observations). This may be due to the fact that the oxygen consumption rate is reduced in hypoxic regions of tissue.
我们在一台CYBER计算机上对稳态条件下周围神经毛细血管及周围组织中氧气的释放、扩散和消耗进行了数学模拟。采用克罗格-厄兰方程计算组织中的氧张力，同时利用控制血红蛋白释放氧气和扩散的微分方程的数值解来计算毛细血管中的氧张力。利用大鼠周围神经中氧溶解度、扩散系数、毛细血管直径、毛细血管密度、神经血流量、氧消耗率和动脉氧张力等参数的平均测量值，我们计算了神经内膜氧张力与距最近毛细血管的距离以及沿毛细血管从动脉端到静脉端的距离的函数关系。计算值范围与从大鼠坐骨神经获得的实验测量值一致。这些参数的改变导致了计算出的氧张力分布的变化。对氧输送产生不利影响的条件包括毛细血管直径减小、毛细血管间距增加、血流量减少和动脉氧张力降低。该模型能够合理地解释糖尿病大鼠坐骨神经中实验获得的较低氧张力，这是基于神经血流量降低33%（与先前测量的血流量减少一致）。然而，实验性半乳糖神经病大鼠坐骨神经中测量到的氧张力降低并不像模型中基于组织圆柱体半径增加22%所预测的那样显著（与实验观察结果一致）。这可能是由于组织缺氧区域的氧消耗率降低所致。
