It was studied water-electrolyte metabolism and system of volumoregulation during short-term space flights, duration of 8–25 day, and in the early readaptation period. The results of research have shown that the volumoregulation change at the initial period of action of weightlessness is consequence of redistribution of blood and hemodinamic of shifts, resulting in change of volumoregulation hormones production and formation of hypohydration of the organism. At more late stages of flight there occurs repeated redistribution of water-electrolyte homeostasis, meanwhile ADH production increases and simultaneously ANP and RAAS hormones release reduces and renal sodium and liquid excretion decreases. After returning to earthly gravitation in majority of cosmonauts adaptive reactions develop, directed at compensation of losses of extracellular fluid and mineral substances for “earthly” water-electrolyte homeostasis formation.
