[Activity of the sympathetico-adrenal system in humans during modeling of weightlessness]

The state of the sympathico-adrenal system (SAS) before and during three days of suited immersion was investigated in six male subjects on the basis of renal excretion of adrenaline (A), noradrenaline (NA), dopamine (DA) and DOPA according to Vasilyev. Computer-aided analysis of the experimental data by the method of principal components showed that the SAS was functionally stressed in all subjects. Suited immersion that simulated hemodynamic, metabolic and vestibulo-motor effects of microgravity helped to distinguish between men with sustained and lowered capabilities of the SAS which are largely determined by the A-, NA-, and mixed type of its function. Clinical manifestations of A-crises in all subjects pointed to central genesis of SAS reactions to simulated microgravity. A correlation between the decline of SAS reserve capabilities and the level of the vestibulo-autonomic syndrome during suited immersion as well as drastic decrease of physical work capacity after immersion was established. It is emphasized that correction of unstable states of the SAS functional activity acquires special importance.