title: Exogenous H2 S enhances mice gastric smooth muscle tension through S-sulfhydration of KV 4.3, mediating the inhibition of the voltage-dependent potassium current.
abstract: BACKGROUND
  Hydrogen sulfide (H2 S) has been shown to have an excitatory effect on gastric motility, but the underlying molecular mechanism is unclear. In this study, we aimed to investigate the possible targets of H2 S and determine how H2 S affects its target proteins during H2 S-induced contraction.
  
  
  METHODS
  Patch-clamp and potentiometric fluorescence dye were utilized to measure the electrophysiological changes. The Biotin-switch assay was utilized to detect the protein S-sulfhydration. The isometric tension measurement was conducted too.
  
  
  RESULTS
  Exogenous H2 S enhanced the tonic contraction of gastric antral smooth muscle, and voltage-dependent potassium channel (KV ) blocker and Dithiothreitol (DTT, a reducing agent) abolished the excitatory effect of NaHS. Exogenous H2 S inhibited the fast inactivation component of the voltage-dependent potassium channel current (IKVfast ) in isolated gastric antral smooth muscle cells. H2 S inhibited the KV 4.3 current in H293 cells with heterologous expression of KV 4.3, but did not inhibit the KV 4.1 and KV 4.2 currents, which together contribute greatly to IKVfast . NaHS significantly decreased the membrane potential in cultured gastric smooth muscle cells, but the NaHS-induced depolarization was suppressed by knockdown of KV 4.3 and N-ethylamaleimide (NEM), a free thiol group blocker. In addition, NaHS sulfhydrated KV 4.3 in H293 cells and in gastric smooth muscle tissue. However, this S-sulfhydration was inhibited by NEM and DTT. Meanwhile the NaHS-induced inhibition of IKVfast and KV 4.3 was also blocked by NEM and DTT.
  
  
  CONCLUSIONS
  These results suggest that exogenous H2 S sulfhydrates KV 4.3 to decrease the membrane potential, thereby enhancing the basal tension of gastric antral smooth muscle.
authors.affiliation: Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: D-H
authors.initials: DH
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: X-M
authors.initials: XM
authors.lastname: Meng
authors.forename: C-M
authors.initials: CM
authors.lastname: Zhang
authors.forename: H-L
authors.initials: HL
authors.lastname: Lu
authors.forename: Y-C
authors.initials: YC
authors.lastname: Kim
authors.forename: W-X
authors.initials: WX
authors.lastname: Xu
mesh_terms: D000818:Animals; D005753:Gastric Mucosa / Q000378:metabolism*; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051672:Shal Potassium Channels / Q000378:metabolism*; D013270:Stomach / Q000187:drug effects
chemical_list: D051672:Shal Potassium Channels; D006862:Hydrogen Sulfide
keywords: H2S; KV4.3; S-sulfhydration; gastrointestinal motility; voltage-dependent potassium current