Regional specialization of the membrane of retinal glial cells and its importance to K+ spatial buffering.
Electrophysiological experiments, obtained primarily from dissociated salamander cells, demonstrate that the K+ conductance of Müller cells is distributed in a highly nonuniform manner over the cell surface. A large fraction of the total cell conductance is localized to that portion of the endfoot process that faces the vitreous humor. Along the remainder of the cell, specific K+ conductance is larger in the outer plexiform layer than in neighboring regions. High-endfoot conductance directs K+ spatial buffering currents preferentially through the endfoot process, leading to an efficient form of spatial buffering termed K+ siphoning. Preliminary experiments suggest that the endfeet of astrocytes also have high K+ conductance.
D000818:Animals; D001001:Anura; D001253:Astrocytes / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D009457:Neuroglia / Q000378:metabolism* / Q000648:ultrastructure; D009900:Optic Nerve / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D014562:Caudata
D007473:Ion Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium