title: Hydrogen sulfide regulates the colonic motility by inhibiting both L-type calcium channels and BKCa channels in smooth muscle cells of rat colon.
abstract: OBJECTIVE
  To examine the hypothesis that hydrogen sulfide (H2S) regulates the colonic motility by modulating both L-type voltage-dependent calcium channels and large conductance Ca2+-activated K+ (BKCa) channels.
  
  
  METHODS
  Immunohistochemistry was performed on rat colonic samples to investigate the localization of the H2S-producing enzymes cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). The contractions of proximal colonic smooth muscle were studied in an organ bath system. The whole-cell patch-clamp technique was used to record both L-type calcium currents (ICa,L) and BKCa currents in colonic smooth muscle cells (SMCs) isolated from male Wistar rats.
  
  
  RESULTS
  Immunohistochemistry revealed the presence of CBS and CSE in mucosa, smooth muscle cells and myenteric neurons. The H2S donor NaHS inhibited spontaneous contractions of the longitudinal muscle and circular muscle strips in a dose-dependent manner, and the inhibitory effects were not blocked by tetrodotoxin. NaHS inhibited the peak ICa,L in colonic SMCs at a membrane potential of 0 mV. The current-voltage (I-V) relationship of L-type calcium channels was modified by NaHS, and the peak of the I-V curve was shifted to the right. NaHS (200 μΜ) evoked a significant rightward shift of the steady-state activation curve and inhibited the inactivation of L-type calcium channels. Furthermore, NaHS reversibly decreased the peak ICa,L in a dose-dependent manner. Likewise, BKCa channels were significantly inhibited by NaHS, and the addition of NaHS caused a time- and dose-dependent reduction in the BKCa current.
  
  
  CONCLUSIONS
  The relaxant effect of H2S on colonic muscle strips may be associated with the direct inhibition of H2S on L-type calcium channels. H2S may be involved in the regulation of calcium homeostasis in colonic SMCs of rat colon.
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.
authors: Xiaojing
authors: X
authors: Quan
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.
authors: Hesheng
authors: H
authors: Luo
authors: Department of Gastroenterology, the Affiliated Hospital of Guilin Medical College, Guilin, China.
authors: Yin
authors: Y
authors: Liu
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China; Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, China.
authors: Hong
authors: H
authors: Xia
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.
authors: Wei
authors: W
authors: Chen
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, China.
authors: Qincai
authors: Q
authors: Tang
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D003106:Colon / Q000187:drug effects* / Q000502:physiology*; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000037:antagonists & inhibitors*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D003541:Cystathionine beta-Synthase; D003542:Cystathionine gamma-Lyase; D006862:Hydrogen Sulfide