The Pressure Reversal of a Variety of Anesthetic Agents in Mice

Abstract

The ability of high pressures to reverse the anesthesia produced by a wide range of general anesthetics were studied in mammals. Dose-response curves were obtained using mice at pressures ranging from 1-125 atm for 5 agents, namely .alpha.-chloralose, ethylcarbamate, phenobarbital and, for comparison, N and Ar. The increase of ED50 was a linear function of pressure in each case, but the proportionate increases in ED50 with pressure were greater for the 3 non-inhalation agents than for the 2 gases. The ratio of ED50 at 100 atm to that at 1 atm was 1.74 for .alpha.-chloralose, 1.68 for ethylcarbamate and 1.54 for phenobarbital. The corresponding ratios for Ar and N were only 1.36 and 1.34. The potencies of 3 short-acting agents (trichloroethanol, ketamine and alphadione) increased with decreasing pressure, although ED50 values could not be obtained. Pressure reverses the actions of a wide variety of anesthetics in mice. These results were not inconsistent with either the fluidized lipid membrane or the critical volume hypotheses of anesthetic action.