The influence of general, volatile anesthetics on the dynamic properties of model membranes.

The microscopic mechanism of general anesthesia is still not known but it may be located in the membrane region of nerve cells. In the present article microwave experiments on model membrane systems are discussed. At these particular frequencies a significant decrease of the systems' complex dielectric function is measured when it is exposed to volatile anesthetics. This effect is reversible as well as being identical for chemically quite different anesthetics. The corresponding anesthetic concentrations in the samples are relevant for medical anesthesia. The underlying microscopic mechanism is a decrease in the Debye relaxation frequency (and correspondingly an increase in viscosity) of those water molecules which are localized at the membranes' surfaces. General anesthesia might be a consequence of such a viscosity change at hydrophilic surfaces.