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Exogenous H 2 S enhances mice gastric smooth muscle tension through S‐sulfhydration of K V 4.3, mediating the inhibition of the voltage‐dependent potassium current
Author(s) -
Liu D.H.,
Huang X.,
Meng X.M.,
Zhang C.M.,
Lu H.L.,
Kim Y.C.,
Xu W.X.
Publication year - 2014
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/nmo.12451
Subject(s) - chemistry , membrane potential , potassium channel , biophysics , patch clamp , charybdotoxin , channel blocker , depolarization , biochemistry , biology , receptor , organic chemistry , calcium
Background Hydrogen sulfide ( H 2 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 H 2 S and determine how H 2 S affects its target proteins during H 2 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. Key Results Exogenous H 2 S enhanced the tonic contraction of gastric antral smooth muscle, and voltage‐dependent potassium channel (K V ) blocker and Dithiothreitol ( DTT , a reducing agent) abolished the excitatory effect of NaHS . Exogenous H 2 S inhibited the fast inactivation component of the voltage‐dependent potassium channel current (IK Vfast ) in isolated gastric antral smooth muscle cells. H 2 S inhibited the K V 4.3 current in H293 cells with heterologous expression of K V 4.3, but did not inhibit the K V 4.1 and K V 4.2 currents, which together contribute greatly to IK Vfast . NaHS significantly decreased the membrane potential in cultured gastric smooth muscle cells, but the NaHS ‐induced depolarization was suppressed by knockdown of K V 4.3 and N‐ethylamaleimide ( NEM ), a free thiol group blocker. In addition, NaHS sulfhydrated K V 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 IK Vfast and K V 4.3 was also blocked by NEM and DTT . Conclusions & Inferences These results suggest that exogenous H 2 S sulfhydrates K V 4.3 to decrease the membrane potential, thereby enhancing the basal tension of gastric antral smooth muscle.