AIM:To study the effects and mechanisms of ethanol on chloride channels in poorly differentiated nasopharyngeal carcinoma CNE-2Z cells.METHODS:The effect of ethanol on the cell growth was analyzed by MTT as-say.The technique of whole-cell patch-clamp was used to detect the chloride current .The characteristics of the chloride current were analyzed by using the chloride channel blockers .The siRNA technique was used to analyze the molecular basis of the ethanol-sensitive chloride channels .RESULTS: Under isotonic conditions , the background current was weak and stable.Ethanol at concentrations of 0.17~170 mmol/L activated a chloride current in a concentration-dependent manner (an inverted U-shape), with a maximum effect at the concentration of 17 mmol/L.The currents showed obviously outward rectification and were susceptible to extracellular hypertonicity and the chloride channel blocker , 5-nitro-2-(3-phenylpropyl-amino) benzoic acid ( NPPB) .ClC-3 siRNA obviously decreased the currents activated by ethanol .CONCLUSION:Ex-tracellular ethanol induces chloride currents through activating the ClC-3 chloride channels .