EFFECTS OF TUMOR-NECROSIS-FACTOR ON INWARD POTASSIUM CURRENT AND CELLMORPHOLOGY IN CULTURED HUMAN OLIGODENDROCYTES

The effects of recombinant human tumor necrosis factor-alpha (rhTNF-al pha) on inward rectifier potassium [K(IR)] currents and on cell morpho logy have been studied in cultured human oligodendrocytes. Cell-attach ed patches were used to isolate and record unitary currents through an inward rectifier K+ channel with a conductance of 23 pS. In control o ligodendrocytes the mean open times showed an exponential dependence o n patch potential with an e-fold decrease over a patch hyperpolarizati on of 28 mV. Treatment of oligodendrocytes with rhTNF (at 250 ng/ml fo r 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 o pen times were reduced by 60% after rhTNF application; the amplitudes of unitary currents or the extrapolated zero-current potentials were n ot significantly changed by the cytokine. The rhTNF treatments were no t cytotoxic to cultured human oligodendrocytes; however, in some exper iments rhTNF caused evident retraction of cell processes. (C) 1993 Wil ey-Liss, Inc.