title: A comparison of the delayed outward potassium current between the nucleus ambiguus and hippocampus: sensitivity to paeonol.
abstract: Whole-cell patch-clamp recordings investigated the electrophysiological effects of 2'-hydroxy-4'-methoxyacetophenone (paeonol), one of the major components of Moutan Cortex, in hippocampal CA1 neurons and nucleus ambiguus (NA) neurons from neonatal rats as well as in lung epithelial H1355 cells expressing Kv2.1 or Kv1.2. Extracellular application of paeonol at 100μM did not significantly affect the spontaneous action potential frequency, whereas paeonol at 300μM increased the frequency of spontaneous action potentials in hippocampal CA1 neurons. Paeonol (300μM) significantly decreased the tetraethylammonium-sensitive outward current in hippocampal CA1 neurons, but had no effect upon the fast-inactivating potassium current (IA). Extracellular application of paeonol at 300μM did not affect action potentials or the delayed outward currents in NA neurons. Paeonol (100μM) reduced the Kv2.1 current in H1355 cells, but not the Kv1.2 current. The inhibitor of Kv2, guangxitoxin-1E, reduced the delayed outward potassium currents in hippocampal neurons, but had only minimal effects in NA neurons. We demonstrated that paeonol decreased the delayed outward current and increased excitability in hippocampal CA1 neurons, whereas these effects were not observed in NA neurons. These effects may be associated with the inhibitory effects on Kv2.1 currents.
authors.affiliation: School of Chinese Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Chin-Tsang
authors.initials: CT
authors.lastname: Yang
authors.affiliation: Department of Physiology, China Medical University, Taichung, Taiwan.
authors.forename: Yuk-Man
authors.initials: YM
authors.lastname: Leung
authors.affiliation: Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan.
authors.forename: Sheng-Feng
authors.initials: SF
authors.lastname: Hsu
authors.affiliation: Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan.
authors.forename: Iona
authors.initials: I
authors.lastname: MacDonald
authors.affiliation: Department of Physiology, China Medical University, Taichung, Taiwan.
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Wang
authors.affiliation: School of Chinese Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Jaung-Geng
authors.initials: JG
authors.lastname: Lin
authors.affiliation: Division of Colorectal Surgery, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan. Electronic address: shihyahung@mail.cmu.edu.tw.
authors.forename: Shih-Ya
authors.initials: SY
authors.lastname: Hung
authors.affiliation: Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan; Department of Photonics and Communication Engineering, Asia University, Taiwan. Electronic address: yihungchen@mail.cmu.edu.tw.
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Chen
mesh_terms: D000098:Acetophenones / Q000494:pharmacology*; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D002460:Cell Line; D055724:Electrophysiological Phenomena / Q000187:drug effects*; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D051669:Shab Potassium Channels / Q000378:metabolism
chemical_list: D000098:Acetophenones; D051669:Shab Potassium Channels; C013638:paeonol; D011188:Potassium
keywords: Action potentials; Hippocampal neuron; Paeonol; Potassium current