[Oxygenation of the frontal cerebral cortex in monkeys during a two-week space flight]

In monkeys (Macaca mulatta) during a two-week space flight and in a ground-based control experiment, with semi-closed platinum electrodes, partial oxygen pressure (pO2) was registered in the frontal cerebral cortex. It was shown that during the flight there is a marked increase of pO2 in the frontal cortex, reaching maximal values on days 5-8 (up to 203%) with a subsequent tendency to normalization by day 11. In the control experiment pO2 values in the cortical zone studied did not exceed the baseline level throughout the period of registration. Analysis of the curves of pO2 oscillations in the frequency range from 0.2 to 0.01 Hz in-flight revealed a shift of the oscillation power spectrum in the long-wave direction which was not seen in the control experiment and suggested a decreased rate of tissue metabolism. As a possible explanation for the noted effects of pO2 dynamics during weightlessness, a combination of a decreased metabolic rate in the brain segment under study with a disorder in the mechanism of regulation of local cerebral blood flow is suggested.