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 lipopolysaccharide (LPS)-activated cultured rat microglial cells by using whole-cell patch clamp method. The current showed `window current' where channels were available for activation but never fully inactivated. At 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 current and depolarize the membrane potential reversibly. These results suggest that 4-AP sensitive I K current plays a direct role of setting the resting membrane potential in LPS-activated microglia.