Effects of Endothelin on Potassium Currents in Primary Cultured Rat Microglia

ABSTRACT

BACKGROUND: Endothelin (ET), potent vasoconstricting peptide, are produced by endothelial cells after brain insults such as ischemia or infection and may play a role in the amplification or regulation of the microglia. In pathology of central nervous system, microglia might become activated leading to altered cellular function in response to brain injury. METHODS: Whole-cell patch clamp technique was used to study the effects of endothelin on changes of potassium currents in cultured rat microglia. Outward and inward rectifying potassium currents were recorded after application of depolarization and hyperpolarization pulses from -60 mV holding potential, respectively. RESULT: ET (100 nM) decreased the amplitude of outward rectifying potassium current and ET-3 was the most potent isoform. Both amplitude and slope conductance of inward rectifying potassium current were increased by ET. After application of ET, the reversal potential of inward potassium current was shifted to left relative to control. CONCLUSION: These results suggest that ET changes the potassium currents and membrane potential of microglia and this depolarizing effect of ET is related with the activation of microglia under pathological conditions of brain