Single ion channel currents in neuropile glial cells of the leech central nervous system

✍ Scribed by Michael Müller; Wolfgang Hanke; Prof. Dr. Wolf-R. Schlue

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 757 KB
• Volume: 9
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/glia.440090404

✦ Synopsis

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 rnediciaulis. We found evidence for two distinct C1-channels that could be distinguished by their basic electrical properties and their responses to different inhibitors on single ion channel currents. In the inside-out configuration in symmetrical C1-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 SO4'could not be detected. The open-state probability of the 70 pS C1-channel increased with membrane depolarization, whereas the open-state probability of the 80 pS C1-channel was voltage-independent. The application of the stilbene derivative DIDS (100 pM) to the cytoplasmic side of the glial cell membrane blocked both C1-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 Zn2 '. Kf channels could only be observed occasionally in the soma membrane of the NG cells. We have characterized a 60 pS Kf 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. o 1993 Wiey-Liss, Inc.