TNF-ALPHA INDUCES A PROTEIN-KINASE C-DEPENDENT REDUCTION IN ASTROGLIAL K+ CONDUCTANCE

INCUBATION of cultured cortical astrocytes with tumor necrosis factor alpha (TNF alpha) led to a marked reduction of membrane potential. Her e we report that this depolarization depends on activation of protein kinase C (PKC), since it could be blocked by the PKC antagonists staur osporine and H7 and it could be mimicked by direct activation of PKC u sing the phorbol ester phorbol 12-myristate 13 acetate (PMA). Analyses of whole cell currents revealed a reduction of inwardly rectifying K currents whereas K+ outward currents were not affected. We conclude t hat TNF alpha induces changes of basic electrophysiological properties of astrocytes which are similar to those induced by proliferation or an in vitro model of traumatic injury. (C) 1998 Rapid Science Ltd.