Abstract: AimTo study the effects of tacrine on _IK and _IA potassium current in primary cultured rat hippocampal neurons. MethodsWhole cell patch clamp and primary rat hippocampal neuron cultures were used. ResultsTacrine was shown to reduce the amplitude of _IK and _IA, in concentration-dependent manners. The IC₅₀s at +40 mV for reduction of _IK and _IA were 23 and 52.6 μmol·L^-1, respectively. Tacrine (30 μmol·L^-1) shifted the steady state activation of _IK and _IA to negative potentials by 12 and 15 mV, respectively. The V_1/2 of activation curves for _IK current before and after the application of tacrine were (6.7±1.4) mV and (-5.4±1.3) mV, respectively. The k of activation curves for _IK current was 13.4+1.3 and 12.5+1.4 without and with tacrine, respectively. The V_1/2 of activation curve for _IA current were (-9.9±2.6) mV and (-24±5) mV in the absence and presence of tacrine, respectively, and the k value was not changed. ConclusionTacrine inhibited _IK and _IA currents in rat hippocampal neurons and it is more potent for blocking _IK.