Electrical properties of isolated demyelinated rat nerve fibres

Abstract

Isolated large rat nerve fibers with diphtheria toxin-induced paranodal demyelination were investigated. These fibers had increased membrane time constant of the demyelinated nodal segment, related to a large increase in capacitance (5-50 times). The resting conductance was less increased (2-3 times), meaning that the internodal axolemma has considerably higher resting resistance than the nodal membrane. A large variation in action potential amplitude was found which was unrelated to the size of the nodal widening and the passive electrical properties.