[Use of mathematical models in study of nitric oxide, myoglobin and cell oxygen regimen].

The influence ofnanomolar concentrations of NO on oxygen regimen of muscle cells was investigated. The intracellular distribution of oxygen consumption rates, pO2, NO and myoglobin was calculated by mathematical modeling of diffusion reactions of O2, NO and myoglobin in the muscle cell. The diffusion of O2, and NO from blood vessel surface into cell was taken into account. According to calculations, NO roughly regulates the oxygen regimen of cell, because it increases the tissue pO2 level by inhibition of mitochondria activity in the whole cell space. The presence ofmyoglobin is capable potentially to modulate the influence of NO on oxygen regimen. Myoglobin not only contributes to tissue O2 supply, but it can locally affect the NO concentration. Acting as an NO scavenger under normoxia and as an NO producer under hypoxia, myoglobin together with NO can provide fine adjustment of muscle oxygen regimen via an increase in tissue pO, and elimination a mismatch between oxygen supply and demand.

[Oxygen transport in skeletal muscles working with its maximum consumption during hypoxemia]. / Transport kysniu v skeletnomu m'iazi pry roboti z maksymal'nym ioho spozhyvanniam za umov hipoksemiï.

The influence of acute hypoxia (35 < or = PaO2 < or = 100 mmHg) on the values of VO2max and parameters of oxygen transport in muscle working at VO2max was studied under different values of muscle blood flow F (80 < or = F < or = 120 ml/(min 100g), blood pH (7.0-7.6), and different diffusion conditions. Investigations were performed on a computer model of O2 delivery to and O2 consumption in the working muscle. VO2max, pvO2, PO2- and VO2-fields in the muscular fiber were calculated. It was shown that the greater the degree of arterial hypoxemia, the lower the muscle VO2max and PvO2 values. The greater the blood flow through muscle, the greater the VO2max. The diffusion conditions produced a powerful influence on the VO2max value. However, with an increasing degree of arterial hypoxemia, the effect of F, intercapillary distances, and blood pH on the value of VO2max is weakened.