[Human sympathetic-adrenal system during water immersion]

The activity of the sympathoadrenal system (SAS) of 12 volunteers exposed to water immersion for 7 days was studied. Before and after water immersion six of the test subjects were exposed to acceleration of +3 Gz for 15 min. It was demonstrated that water immersion increased the hormonal activity and decreased the transmitter activity of the SAS. Exposure to acceleration stimulated the SAS, thus increasing immersion tolerance.