Fit of the dielectric anomaly of squid axon membrane near heat-block temperature to the ferroelectric Curie-Weiss law.

In a 1969 experiment, Palti and Adelman reported that the capacitance of squid axon membrane rises sharply with temperature between 40 and 50 degrees C. This phenomenon is here explained by the ferroelectric-superionic transition hypothesis, which also explains channel gating and other phenomena observed in excitable membranes. According to this hypothesis gating in the Na channel is due to a first-order phase transition from a ferroelectric (closed) state to a superionic (open) state. From it, the dielectric permittivity of the Na channel, and hence the temperature-dependent component of membrane capacitance, is predicted to obey the ferroelectric Curie-Weiss law near the transition (heat-block) temperature. The Palti-Adelman data are fitted accurately by the predicted relationship. The parameters obtained permit an estimate to be made of the Curie constant of the channel, approximately 6400 K, consistent with an order-disorder ferroelectric. The Na channel appears to be a ferroelectric polymer component of a lyotropic lamellar liquid crystal.