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Resolving three types of chloride channels in demyelinated Xenopus axons
Author(s) -
Wu J. V.,
Shrager P.
Publication year - 1994
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490380603
Subject(s) - depolarization , chloride channel , dids , xenopus , biophysics , chemistry , rectification , membrane potential , hyperpolarization (physics) , physics , voltage , stereochemistry , biology , biochemistry , membrane , quantum mechanics , nuclear magnetic resonance spectroscopy , gene
Axons from Xenopus sciatic nerve were demyelinated by intraneural injection of lysolecithin rendering the entire internodal axolema accessible to a patch electrode. In this region, three types of anion selective pores were found and characterized at the single‐channel level. These included outwardly rectifying, inwardly rectifying, and maxi Cl − channels. The outwardly rectifying Cl − channels (24 pS) are activated by depolarization with a weak voltage dependence of 42 mV per e ‐fold change in open probability. The inwardly rectifying Cl − channels (27 pS) are insensitive to voltage, but can be blocked by internal application of 100 μM SITS or DIDS. The I‐V curves of rectifying channels are S‐shaped and can be fitted by a kinetic model with a single free energy barrier. The rectification may be related to the location of this barrier. The maxi Cl − channel (335 pS) is often open at the resting potential, but is inactivated by a large depolarization. The rectification, voltage dependence, and inactivation of these channels may contribute to the regulation of axonal Cl − balance and resting potential. © 1994 Wiley‐Liss, Inc.