O₂ Transport in Cerebral Microregions (Mathematical Simulation)

The effects of the circulation rate in capillaries, the intensity of O₂ consumption by nerve cells and the capillary network density on the O₂ tension distribution in the cerebral cortex have been studied, utilizing a mathematical model simulating actual neuron-capillary relationships. The model has been written as a system of equations in partial derivatives, its solution obtained by the net-point method. Regulatory variations of the capillary circulation rate in certain cerebral microregions have been shown to ensure similar changes in oxygen supply throughout the region. A drop of the pO₂ level in a cerebral microregion with a rising O₂ consumption by nerve cells is shown to be due, by 75 percent, to the increase of O₂ consumption and by 25 percent, to the lower pO₂ in the capillaries. Conversely, an increase in pO₂ in microregions resulting from a lower O₂ consumption by neurons is due by 75 percent, to a pO₂ rise in capillaries and by 25 percent, at the expense of an O₂ consumption decrease. In cerebral regions differing in capillary network density by 20 percent, changes in the conditions for oxygen supply to tissue are due by 1/3 to pO₂ variations in the capillaries and by 2/3 to alterations in the diffusion distances.