title: Apocynum venetum leaf aqueous extract inhibits voltage-gated sodium channels of mouse neuroblastoma N2A cells.
abstract: BACKGROUND
  Apocynum venetum Linn. (Apocynaceae family), also called Luobuma, is a shrub which grows widely in the Xinjiang Autonomous Region of China. Its leaves are used in herbal tea for the treatment of hypertension, anxiety and depression. Animal studies have also shown that Apocynum venetum leaf extract (AVLE) also exerts anti-depressant and anti-anxiety activities. The effects of AVLE on neuronal tissues in vitro are not fully understood.
  
  
  METHODS
  Using the whole-cell voltage-clamp method, we studied the effects of AVLE on ion channels in cultured mouse neuroblastoma N2A cells.
  
  
  RESULTS
  AVLE inhibited voltage-gated inward Na(+) current in a reversible and concentration-dependent manner (half-inhibitory concentration was 18 μg/ml and maximum inhibition at 100 μg/ml). AVLE specifically promoted steady-state inactivation of Na(+) channels but did not affect voltage-dependence of activation. The inhibitory effect was not use-dependent and was not affected by 300μM L-NAME, suggesting that NO was not involved in the action of AVLE in neuronal cells. AVLE also had a mild inhibitory effect on voltage-gated K(+) channels, but did not affect ATP-sensitive K(+) channels.
  
  
  CONCLUSIONS
  Since voltage-gated Na(+) and K(+) channels are associated with neuronal excitability and therefore affect neurotransmission, the modulation of neuronal ion channels by AVLE may exert neuropharmacological effects. In particular, the inhibition of voltage-gated Na(+) currents by AVLE may in part account for the psychopharmacological effects of this herbal remedy.
authors.affiliation: Graduate Institute of Neural and Cognitive Sciences, China Medical University, Taichung 40402, Taiwan.
authors.forename: Chang-Shin
authors.initials: CS
authors.lastname: Kuo
authors.forename: Chiu-Yin
authors.initials: CY
authors.lastname: Kwan
authors.forename: Chi-Li
authors.initials: CL
authors.lastname: Gong
authors.forename: Min-Fan
authors.initials: MF
authors.lastname: Tsai
authors.forename: S
authors.initials: S
authors.lastname: Nishibe
authors.forename: J
authors.initials: J
authors.lastname: Tatsuzaki
authors.forename: Yuk-Man
authors.initials: YM
authors.lastname: Leung
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D000928:Antidepressive Agents / Q000494:pharmacology*; D030010:Apocynum; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009447:Neuroblastoma; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects* / Q000502:physiology
chemical_list: D014151:Anti-Anxiety Agents; D000928:Antidepressive Agents; D004791:Enzyme Inhibitors; D018377:Neurotransmitter Agents; D010936:Plant Extracts; D024642:Potassium Channels, Voltage-Gated; D015222:Sodium Channels; D012964:Sodium; D019331:NG-Nitroarginine Methyl Ester