[Effect of electrical stimulation of nodes of Ranvier on the rate of sodium channel modification by batrachotoxin under conditions of potential fixation].

Voltage clamp experiments were carried out on Ranvier nodes treated with steroidal alkaloid batrachotoxin (BTX). It is shown that the electric stimulation of voltage clamped Ranvier node with depolarizing pulses strongly increases the rate of BTX-Na channel interaction providing that two conditions take place simultaneously: sodium channels are not inactivated at the holding potential and applied pulses are large enough to activate Na channels. It is supposed that BTX interacts only with open sodium channels and that BTX-channel reaction is reversible. The electric stimulation is the way to obtain a marked fraction of modified channels in experiments even with low BTX concentrations (100--500 mM) and to achieve an equilibrium for BTX-Na channels reaction for a short time.