title: [Inhibition of tacrine on delayed rectifier and transient outward potassium currents in cultured rat hippocampal neurons].
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  Tacrine inhibited IK and IA currents in rat hippocampal neurons and it is more potent for blocking IK.
authors.affiliation: Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Hong-wei
authors.initials: HW
authors.lastname: Jin
authors.forename: Shao-feng
authors.initials: SF
authors.lastname: Xu
authors.forename: Lin-tao
authors.initials: LT
authors.lastname: Qu
authors.forename: Xiao-liang
authors.initials: XL
authors.lastname: Wang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000166:cytology / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects*; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013619:Tacrine / Q000494:pharmacology*
chemical_list: D002800:Cholinesterase Inhibitors; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D013619:Tacrine