[Mechanisms of early changes in water-electrolyte metabolism in man in various ground-based models of the effects of microgravity].

Analysed was an array of data amassed in 4 series of experiments with simulated microgravity effects (HDT (-6 degrees); dry and suited immersions in horizontal and vertical position). Water-electrolyte turnover in blood and urine and hormonal controls have been under study. It was demonstrated that irrespective of the body axis position relative to the gravity vector in the immersion models, reactions of the active regulation of the water--electrolyte metabolism were noted already within the initial hours, i.e. more rapidly than in HDT. During the early phase of adaptation to the immersion models, some ostensibly similar responses were governed by different hormonal controls. Unlike the dry immersion, the suited immersion tests with various body positioning modified not only the strength but the dynamics of the water-electrolyte regulation, too. Findings also included differences in the dynamics osmo- and volumoregulation in the vertical and horizontal suited immersion tests which are, possibly, reflective of recruitment of different stimulating mechanisms and efficiency of organs-targets.