[Anesthesia mechanisms: nerve excitation and temperature].

Depolarization of a nerve membrane produces heat while repolarization absorbs heat. This is equivalent to the phase transition of water where freezing of water produces heat and melting of ice absorbs heat. In this context, high temperature (as in water) supports resting potential and low temperature (as in ice) supports action potential. When assessed by the equilibrium between the two phases, anesthetized state is the high temperature state. Nevertheless, low temperature supports anesthesia. The two opposing facts confuse the understanding of anesthesia mechanisms. The inconsistency arises from the two effects of heat on nerve excitation. One is one the equilibrium between the resting and active states of the excitation machinery, and the other is on the reaction rate process. This review annotŁatsz why low temperature facilitates anesthesia while high temperature supports the resting state of nerves.