title: ASIC-like currents in freshly isolated cerebral artery smooth muscle cells are inhibited by endogenous oxidase activity.
abstract: OBJECTIVE
  The aim of this study was to determine if VSMC ASIC-like currents are regulated by oxidative state.
  
  
  METHODS
  We used whole-cell patch clamp of isolated mouse cerebral VSMCs to determine if 1) reducing agents, such as DTT and GSH, and 2) inhibition of endogenous oxidase activity from NADPH and Xanthine oxidases potentiate active currents and activate electrically silent currents.
  
  
  RESULTS
  Pretreatment with 2 mM DTT or GSH, increased the mean peak amplitude of ASIC-like currents evoked by pH 6.0 from 0.4 ± 0.1 to 14.9 ± 3.6 pA/pF, and from 0.9 ± 0.3 to 11.3 ± 2.4 pA/pF, respectively. Pretreatment with apocynin, a NADPH oxidase inhibitor, mimics the effect of the reducing agents, with the mean peak current amplitude increased from 0.9 ± 0.5 to 7.0 ± 2.6 pA/pF and from 0.5 ± 0.2 to 26.4 ± 6.8 pA/pF by 50 and 200 μM apocynin, respectively. Pretreatment with allopurinol, a xanthine oxidase inhibitor, also potentiates the VSMC ASIC-like activity.
  
  
  CONCLUSIONS
  These findings suggest that VSMC ASIC-like channels are regulated by oxidative state and may be inhibited by basal endogenous oxidative sources such as NADPH and xanthine oxidase.
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA.
authors.forename: Wen-Shuo
authors.initials: WS
authors.lastname: Chung
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Farley
authors.forename: Heather A
authors.initials: HA
authors.lastname: Drummond
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D062565:Acid Sensing Ion Channels; D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002536:Cerebral Arteries / Q000166:cytology; D004229:Dithiothreitol / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D032389:Myocytes, Smooth Muscle / Q000201:enzymology / Q000502:physiology*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D019163:Reducing Agents / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism / Q000502:physiology*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000098:Acetophenones; D062565:Acid Sensing Ion Channels; D009419:Nerve Tissue Proteins; D019163:Reducing Agents; D015222:Sodium Channels; D000493:Allopurinol; C056165:acetovanillone; D014969:Xanthine Oxidase; D019255:NADPH Oxidases; D005978:Glutathione; D004229:Dithiothreitol