Anesthetic Action of Inert and Unreactive Gases on Intact Animals and Isolated Tissues

Abstract

A comparison was made of the central nervous system depressant action of 11 chemically unreactive gases with reference to the partial pressure of each that is necessary to protect 50% of a group of mice from electro-shock convulsive seizures. At consistently higher pressures 6 of 7 of the gases tested diminish excitability, block conduction and produce significant depolarization of isolated rat peripheral nerve. The depressant action of these substances is fundamentally related to the facility with which they dissolve in olive oil or a non-polar liquid to produce a critical concn. of molecules at their site of action. The relative solubility of a gas in olive oil or a non-polar liquid is inversely proportional to its standard state fugacity. For 2 gases of very high molecular weight, smaller amounts were dissolved than would be predicted by this rule and the relation between the depressant action of a gas and its fugacity is not so clear.