Fig. 11

Mean responses of arterial pressure at the level of the brain (brain AP) of 12 rats with anti-G equipment exposed to +5.0 Gz acceleration for 15 s. +Gz and internal suit pressure were expressed by logarithmic scales. **p < 0.01 by one-factor ANOVA with the Tukey–Kramer test. An anti-G suit could dramatically block the +5.0-Gz-induced severe hypotension and kept the brain arterial pressure to the control level. Still, however, decreases in brain AP were observed twice; first during the increasing +Gz phase but before activation of an anti-G suit (the acceleration hypotension), and later during the decreasing +Gz phase after deactivation of an anti-G suit (the deceleration hypotension). The deceleration hypotension was significantly greater than the acceleration hypotension, although the loaded Gz and internal suit pressure during the deceleration hypotension phase were almost equal to those during the acceleration hypotension phase [17, 18, 22]. A slower onset or offset rate of acceleration in our centrifuge may permit to observe both of hypotensions, however the obtained data shows that the G-decreasing deceleration phase has more damage-full potentials built in than the G-increasing acceleration phase