Comparative responsiveness of the rapidly acting arterial pressure control system to quick mild hemorrhage and infusion in conscious rabbits.

The responsiveness of the rapidly acting arterial pressure control system to hemorrhage and infusion was investigated. Two catheters, one for pressure measurement and the other for inducing hemorrhage and infusion, were chronically implanted in 19 rabbits. A few days after the operation, each animal was quickly bled and transfused (2 ml/kg body weight) at intervals of 5 min while it was conscious. The hemorrhage-infusion experiment was repeated 16 times in each animal. The 16 strings of data were pooled for each animal. The overall open-loop gains (G) of the rapidly acting arterial pressure control system were estimated from the individually pooled responses to hemorrhage and infusion. There was no significant difference between the G-values, i.e., 7.2 +/- 1.2 by hemorrhage and 7.1 +/- 1.2 by infusion (mean +/- SD), as evaluated by the paired t-test (p greater than 0.5). Thus, the responsiveness of the rapidly acting arterial pressure control system to quick mild hemorrhage and to infusion appears to be similar.