[Mechanisms of volume regulation under the effect of spaceflight factors]

Studied was the significance of the volume regulating system of the human body for adaptive readjustment of the water-electrolyte homeostasis to changed position, immersion, and microgravity. Experiments were made to investigate volume regulation and associated events and their sequence as during simulation studies (bed rest, immersion, tilting, g-loads), so in Salyut-7 and Mir missions from 7 to 438 days of length. Established was a distinct relationship between the central venous pressure and hydration state of the body, and determined were quantitative parameters of circulating blood migration along the body axis during HDT and hypovolemia. The experiments revealed interdependence of g-tolerance and the way hypohydration had been triggered by, the mechanism of which was also explored. Investigations of human early adaptation to space flight allowed development of an approach to the hydration control (pharmacological hypohydration) with the purpose to minimize discomfort and to improve human performance at the beginning of space mission.