DELAYED RECTIFIER POTASSIUM CURRENTS INDUCED IN ACTIVATED RAT MICROGLIA SET THE RESTING MEMBRANE-POTENTIAL

The delayed rectifying outward K+ (I-K) current was measured in lipopo lysaccharide (LPS)-activated cultured rat microglial cells by using wh ole-cell patch clamp method. The current showed 'window current' where channels were available for activation but never fully inactivated. A t near resting membrane potential some part of the current was able to be activated by depolarization. Among the several K+ channel blockers tested, only 4-aminopyridine (4-AP) was able to block most of the cur rent and depolarize the membrane potential reversibly. These results s uggest that 4-AP sensitive I-K current plays a direct role of setting the resting membrane potential in LPS-activated microglia. (C) 1998 El sevier Science ireland Ltd.