Mechanism of the voltage-induced conductance change in the Na channel

A mechanism proposed for the voltage-dependent sodium channel postulates solid-state Na⁺ conduction through the polypeptide structure. Ion conduction is assumed to be state solid-state, through the protein subunits of the channel, rather than aqueous, through a hypothetical pore. The channel conformational change is taken to be a phase transition, with the closed state ferroelectric and the open state superionically conducting. This hypothesis is consistent with the known experimental properties of the channel, and it explains channel properties that current theories are unable to explain-in particular, the initiation of a sodium current by a membrane depolarization. The hypothesis explains channel hysteresis, heat and cold block, magnitude of surface charge, and other observed properties