Ethanol modulates the ionic permeability of sodium channels in rat sensory neurons.

The effects of ethanol on tetrodotoxin-sensitive (TTXs) and tetrodotoxin-resistant (TTXr) sodium channels in rat spinal ganglia were studied using a patch-clamp method. Application of ethanol (10 and 100 mM) to both sides of membranes resulted in decreases in the reversion potentials of both types of sodium channels. In the case of TTXr channels, ethanol decreased their selectivity in relation to Na ions and altered the sequence of ion selectivity of these channels for different cations from row X to row XI of the Eisenman selectivity classification. It is suggested that this change in ion selectivity is associated with ethanol-induced disruption of hydrogen bonds which stabilize the spatial structure of ion channel macromolecules, which may lead to changes in the steric parameters of the pores formed by these channels.