A function of delayed rectifier potassium channels in glial cells: maintenance of an auxiliary membrane potential under pathological conditions.
Müller glial cells from human and guinea-pig retinae were investigated using the whole-cell patch-clamp technique. Human Müller cells from eyes with different diseases were characterized by diminished inwardly-rectifying K(+) currents. A comparable reduction of these currents was achieved in guinea pig Müller cells by treatment with iodoacetate to generate ischemia-like conditions. Consequently, the membrane potentials were reduced significantly in both diseased human and iodoacetate-treated guinea-pig Müller cells as compared to normal controls. However, the potentials were still clearly negative. Delayed rectifier currents could still be recorded under these conditions. Application of quinine blocked the delayed rectifier K(+) channels, and resulted in a total breakdown of the membrane potentials. Thus, it becomes apparent that the glial delayed rectifier K(+) channels are necessary to maintain an 'auxiliary' membrane potential under certain pathological conditions that are characterized by an almost total loss of inward rectifier conductance. Therefore, the delayed rectifier K(+) channels of glial cells may become crucial for the support of basic glial functions.
Pannicke
T
T
Paul-Flechsig-Institute for Brain Research, Department of Neurophysiology, University of Leipzig, Jahnallee 59, D-04109, Leipzig, Germany. pant@server3.medizin.uni-leipzig.de
Faude
F
F
Reichenbach
A
A
Reichelt
W
W
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051668:Delayed Rectifier Potassium Channels; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007461:Iodoacetates / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009457:Neuroglia / Q000737:chemistry* / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D011803:Quinine / Q000494:pharmacology; D012160:Retina / Q000737:chemistry / Q000166:cytology* / Q000503:physiopathology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D018630:Vitreoretinopathy, Proliferative / Q000503:physiopathology*
D051668:Delayed Rectifier Potassium Channels; D004791:Enzyme Inhibitors; D007461:Iodoacetates; D009125:Muscle Relaxants, Central; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D000255:Adenosine Triphosphate; D011803:Quinine