[Water and electrolyte content of the organs and tissues of male rats following a flight on the Kosmos 1667 biosatellite].

After the 7-day space flight onboard the biosatellite Cosmos-1667 the water, Na, K, Ca and Mg content of the liver, kidney, heart, skin and bone of male rats was measured. No significant changes in the weight or water content of the above organs were seen. The exception was a decrease of water contained in the heart and an increase of water contained in the caudal appendage of the epididymis. After flight the mineral composition of the liver was identical to that after control studies. The K content of the heart of the flight rats was lower and that of Na, Ca and Mg was identical to the parameter in the controls. The K content of the skin and bone increased and the Na content of the skin also grew. In the kidney the Ca content did not change whereas the content of K, Na and Mg decreased significantly. In the testis Na decreased and K increased after flight. Thus, changes in fluid-electrolyte homeostasis at the organ and tissue level can develop within 7 days of space flight. They occur not only in the musculoskeletal system but may also evolve in the nonweight-bearing organs.