Effects of tumor necrosis factor on inward potassium current and cell morphology in cultured human oligodendrocytes.
The effects of recombinant human tumor necrosis factor-alpha (rhTNF-alpha) on inward rectifier potassium [K(IR)] currents and on cell morphology have been studied in cultured human oligodendrocytes. Cell-attached patches were used to isolate and record unitary currents through an inward rectifier K+ channel with a conductance of 23 pS. In control oligodendrocytes the mean open times showed an exponential dependence on patch potential with an e-fold decrease over a patch hyperpolarization of 28 mV. Treatment of oligodendrocytes with rhTNF (at 250 ng/ml for 24-48 h) had significant actions to diminish the mean open times of K(IR) relative to control values. At cell resting potential the mean open times were reduced by 60% after rhTNF application; the amplitudes of unitary currents or the extrapolated zero-current potentials were not significantly changed by the cytokine. The rhTNF treatments were not cytotoxic to cultured human oligodendrocytes; however, in some experiments rhTNF caused evident retraction of cell processes.
McLarnon
J G
JG
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Michikawa
M
M
Kim
S U
SU
D000368:Aged; D004594:Electrophysiology; D006801:Humans; D008875:Middle Aged; D009836:Oligodendroglia / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D015221:Potassium Channels; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D011188:Potassium