title: The inhibitory effects of nifedipine on outward voltage-gated potassium currents in mouse neuroblastoma N2A cells.
abstract: BACKGROUND
  Voltage-gated K(+) (Kv) channels have a pivotal role in tuning the action potential duration and excitability in neuronal cells. Although Ca(2+) channel antagonist nifedipine exhibited an inhibitory effect on cardiac Kv currents, a possible action of nifedipine on neuronal Kv currents has not been fully investigated.
  
  
  METHODS
  The effects of nifedipine on elicited Kv currents were characterized using whole-cell recording in mouse neuroblastoma N2A cells.
  
  
  RESULTS
  Exposure to nifedipine induced a dose-dependent inhibition of Kv currents with an IC50 value of 22.3±4.2μM and prolonged the time course of activation. The half-maximum activation potential was 1.6±1.7mV in control conditions and became 13.5±1.5mV in 50μM nifedipine. In addition, the decay rate of Kv currents was substantially accelerated by 39.5% at +60mV. For the voltage-dependent inactivation, the half-maximum inactivation potential was -13.8±0.8mV and strongly shifted to the left following treatment with 50μM nifedipine.
  
  
  CONCLUSIONS
  Treatment with nifedipine exerted a strong influence on the activation and inactivation rate of Kv currents as well as an obvious leftward shift in the inactivation curve. These data indicated that nifedipine exerted an inhibitory effect on Kv currents in N2A cells.
authors.affiliation: Graduate Institute of South-Central University for Nationalities, Wuhan, China.
authors.forename: Xiao-Yue
authors.initials: XY
authors.lastname: Qiu
authors.affiliation: Graduate Institute of South-Central University for Nationalities, Wuhan, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Neurobiology, College of Life Science, South-Central University for Nationalities, Wuhan, China.
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Li
authors.affiliation: Department of Neurobiology, College of Life Science, South-Central University for Nationalities, Wuhan, China. Electronic address: li56567@yeah.net.
authors.forename: Xian-Tao
authors.initials: XT
authors.lastname: Li
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D008564:Membrane Potentials / Q000187:drug effects*; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors*
chemical_list: D024642:Potassium Channels, Voltage-Gated; D009543:Nifedipine
keywords: Kv currents; N2A cells; Nifedipine; Voltage-dependent manner