[Inhibition of tacrine on delayed rectifier and transient outward potassium currents in cultured rat hippocampal neurons]

Abstract

Aim: To study the effects of tacrine on IK and IA potassium current in primary cultured rat hippocampal neurons.

Methods: Whole cell patch clamp and primary rat hippocampal neuron cultures were used.

Results: Tacrine 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 mumol.L-1, respectively. Tacrine (30 mumol.L-1) shifted the steady state activation of IK and IA to negative potentials by 12 and 15 mV, respectively. The V1/2 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 V1/2 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.

Conclusion: Tacrine inhibited IK and IA currents in rat hippocampal neurons and it is more potent for blocking IK.