Control of extracellular potassium levels by retinal glial cell K+ siphoning.
Efflux of K+ from dissociated salamander Müller cells was measured with ion-selective microelectrodes. When the distal end of an isolated cell was exposed to high concentrations of extracellular K+, efflux occurred primarily from the endfoot, a cell process previously shown to contain most of the K+ conductance of the cell membrane. Computer simulations of K+ dynamics in the retina indicate that shunting ions through the Müller cell endfoot process is more effective in clearing local increases in extracellular K+ from the retina than is diffusion through extracellular space.
D000557:Ambystoma; D000818:Animals; D005110:Extracellular Space / Q000378:metabolism*; D008839:Microelectrodes; D009457:Neuroglia / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*
D011188:Potassium