title: Efficient K+ buffering by mammalian retinal glial cells is due to cooperation of specialized ion channels.
abstract: Radial glial (Müller) cells were isolated from rabbit retinae by papaine and mechanical dissociation. Regional membrane properties of these cells were studied by using the patch-clamp technique. In the course of our experiments, we found three distinct types of large K+ conducting channels. The vitread process membrane was dominated by high conductance inwardly rectifying (HCR) channels which carried, in the open state, inward currents along a conductance of about 105 pS (symmetrical solutions with 140 mM K+) but almost no outward currents. In the membrane of the soma and the proximal distal process, we found low conductance inwardly rectifying (LCR) channels which had an open state-conductance of about 60 pS and showed rather weak rectification. The endfoot membrane, on the other hand, was found to contain non-rectifying very high conductance (VHC) channels with an open state-conductance of about 360 pS (same solutions). These results suggest that mammalian Müller cells express regional membrane specializations which are optimized to carry spatial buffering currents of excess K+ ions.
authors: Julius Bernstein Institute of Physiology, Martin Luther University Halle, German Democratic Republic.
authors: B
authors: B
authors: Nilius
authors: A
authors: A
authors: Reichenbach
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D007473:Ion Channels / Q000378:metabolism*; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D011188:Potassium