Investigating the Metabolic Reactions of Subjects with Four-Month Isolation in a Hermetic Volume under Stress Conditions

In the dynamics of the international experiment with 120-day isolation in the hermetic volume SIRIUS 19, a crew of six people of both sexes aged from 27 to 46 years was examined. The subjects were divided into two groups of three people based on gender. In addition to the impact of the pressurized volume factors, the participants were exposed to a complex of stress factors, particularly, constant intense physical exertion and exercise tests, intense operator performance in the time shortage, 24-h sleep deprivation, and imitation of extravehicular and on-planetary activities. In the blood of the volunteers, the values of 42 biochemical parameters were determined, reflecting the state of the main metabolic components, as well as internal organs and tissues. It was found that metabolic reactions of the participants in the experiment with 120-day isolation in a pressurized volume, in contrast to the previous similar experiments, were determined by the constant stress-generating effect of high-intensity preventive physical exertion and were characterized by an increase in the activity of muscle enzymes, activation of lipolysis, decrease in the level of serum iron, and deceleration of the glomerular filtration rate in kidneys due to an increase in the blood concentration of cystatin C. The gender differences between groups consisted in a greater manifestation of the detected changes in men compared with women. The detected shifts can be interpreted as adaptive.