Molecular mechanism of inhalation anesthesia and phase transition of lipid membranes

This paper is dedicated to Professor Mase, S. of Kyushu University. In this paper the molecular mechanism of inhalation anesthesia is reviewed. The effect of anesthetics upon the phase transition temperature of lipid membranes correlates with the anesthetic potency. Hydrostatic pressure antagonizes the anesthetic effect. Thus, inhalation anesthesia is considered to be a physico-chemical process. The transition temperature of lipid membranes is colligatively depressed by anesthetics. On the other hand, certain anesthetics broaden the width of the temperature span of the transition, while others do not. Solid solution theory is employed to elucidate the depression of the phase transition temperature and the width of the temperature span of the transition simultaneously.