Ionic mechanisms of depolarization responses in Helix pomatia neurons to glutamate application

Abstract

Reversal potentials of transmembrane ionic currents induced by glutamate were determined in various D neurons ofHelix pomatia. Two types of neurons were found with mean reversal potentials of −10.6±1.2 and −40.0±0.6 mV. Neurons of the first group responded under ordinary conditions to glutamate application by a volley of action potentials. Neurons of the second group did not generate action potentials under the same conditions during glutamate application. With an increase in the dose of mediator the amplitude of D responses in these neurons increased only up to a certain limit, without reaching the critical depolarization level of the cell; a fall in the external chloride ion concentration led to a decrease in their reversal potential. The possible ionic mechanisms of glutamate-dependent depolarization responses of these groups of neurons are discussed.