Effect of anesthetics on the self-sustained oscillation in an artificial membrane induced by repetitive conformational change of DOPH molecules between hydrophilic and hydrophobic phases

Abstract

The mechanism of anesthesia was approached from a study of an artificial excitable membrane that well reproduced the active electrical properties of the nerve membrane. Self-sustained oscillations of the membrane potential in a model membrane in which dioleyl phosphate (DOPH) was infiltrated into the pores of a millipore filter were utilized to investigate the effect of volatile anesthetic agents on the repetitive conformational change of DOPH molecules between hydrophilic multibilayers and hydrophobic oil droplets, while this process was coupled with diffusion of K+ across the membrane placed between KCl aqueous solutions. The period of the self-sustained oscillations increased due to the addition of volatile anesthetics to the aqueous solutions, and there were critical values of concentrations of volatile anesthetics above which the self-sustained oscillations disappeared. The volatile anesthetic agents affected the hydrophobic oil droplets of the DOPH molecules and impeded their repetitive conformational change between the hydrophilic and hydrophobic phases, just as local anesthetics had been reported to do.