Journal of Applied Physiology, Vol 61, Issue 6 2005-2011, Copyright © 1986 by American Physiological Society
Prolonged exposure of mice to He-O2 at high pressure: effects on seizure and anesthesia liability
R. W. Brauer, J. A. Dutcher, W. Hinson and W. S. Vorus
Multiday exposures of CD-1 mice to He-O2 atmospheres at pressures from 30
to 100 atm result in marked increases of threshold pressures for type I
high-pressure neurological syndrome seizures. The effect develops with a
half time (t1/2) of 12 h and is reversible (t1/2 = 7 h). The maximum
enhancement of Pc is attained at a conditioning pressure of 80 ATA.
Pressure conditioning also results in suppression of the compression rate
effect on Pc. Furthermore, reserpine blocks the increase in Pc during
prolonged pressure exposure. The entire effect thus appears to be an
extension in time of the monoaminergic compression rate effect on Pc.
Pressure conditioning does not modify anesthesia tolerance, unlike N2
habituation which affects anesthesia threshold pressure as well as Pc. The
results are compared with the effects of habituation to inert-gas narcotics
and the implications of the data for an understanding of inert-gas
high-pressure antagonism in intact animals are discussed.
