Temperature and per se hydrostatic pressure reversal of pentobarbital anesthesia in fish

Investigations have been made into the effects of temperature (between 10 and 19 degrees C) on the one hand, and hydrostatic pressure per se (101 ATA) on the other, on recovery time from anesthesia (pentobarbital) in a fish (Salmo gairdneri R). At each of the two pressures studied (1 and 101 ATA) the rise in temperature shortens the recovery period, after a treatment by a constant dose of pentobarbital. Under hyperbaric pressure conditions (101 ATA) the duration of anesthesia is lower than the control value obtained at barometric pressure, whatever the temperature. The analysis of the results shows a similarity between the effects of temperature and pressure on the recovery from pentobarbital anesthesia on the one hand and on chemical kinetics on the other. The results support the hypothesis of the direct action of hydrostatic pressure per se at molecular level.