[The effect of complex barometric exposure on hemodynamics during simulation of the physiological impacts...

In experiments with anesthetized cats effects of breathing under negative pressure (BNP, -5 cm of water column) combined with lower body negative pressure (LBNP, -20 cm of water column) on the cardiorespiratory reactions to postural simulation of the hemodynamic shifts in microgravity were studied. Evidence was obtained that this complex barometric exposure of tilted animals (-30 degrees) imitated the central and peripheral hemodynamics characteristic of tilt at the calculated inclination of +6 degrees up to +12 degrees. Extrapolation of the experimental data on the orthodox physiological model of microgravity (HDT, -6 degrees) allows an assumption that the protocol of complex barometric exposure tested in this experiment transforms the hemodynamic parameters under study to the levels close to those in the vertical body. Results of the investigation infer an additive character of the complex barometric exposure (LBNP + BNP) and its utility as a model of orthostatic g-loads.