Premium
Single ion channel currents in neuropile glial cells of the leech central nervous system
Author(s) -
Müller Michael,
Hanke Wolfgang,
Schlue WolfR.
Publication year - 1993
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.440090404
Subject(s) - dids , leech , depolarization , biophysics , membrane potential , ion channel , hirudo medicinalis , patch clamp , biology , electrophysiology , neuron , neuroscience , membrane , biochemistry , receptor , world wide web , computer science
The patch‐clamp technique was used to investigate the activity of single ion channels in neuropile glial (NG) cells in the central nervous system (CNS) of the medicinal leech, Hirudo medicinalis. We found evidence for two distinct Cl − channels that could be distinguished by their basic electrical properties and their responses to different inhibitors on single ion channels currents. In the Inside‐out configuration in symmetrical Cl solutions, these channels showed current‐voltage relationships with slight outward rectification, mean conductances of 70 and 80 pS, and reversal potentials near 0 mV. Significant permeability to Na + , K + , or SO 4 2− could not be detected. The open‐state probability of the 70 pS Cl − channel increased with membrane depolarization, whereas the open‐state probability of the 80 pS Cl − channel was voltage‐independent. The application of the stilbene derivative DIDS (100 μM) to the cytoplasmic side of the glial cell membrane blocked both Cl − channels. The activity of the 70 pS channel was blocked irreversibly by DIDS, whereas the activity of the 80 pS channel reappeared after wash‐out of DIDS. Both channels were blocked reversibly by 1 mM Zn 2+ . K + channels could only be observed occasionally in the soma membrane of the NG cells. We have characterized a 60 pS K + channel with a high selectivity for K + over Na + . The low density of K + channels in the soma membrane may indicate a non‐uniform distribution of this channel type in NG cells. © 1993 Wiley‐Liss, Inc.