title: Mechanisms of action of the gasotransmitter hydrogen sulfide in modulating contractile activity of longitudinal muscle of rat ileum.
abstract: OBJECTIVE
  This study aims to determine mechanisms of action of the gasotransmitter hydrogen sulfide (H(2)S) on contractile activity in longitudinal muscle of rat ileum.
  
  
  METHODS
  Ileal longitudinal muscle strips were prepared to measure isometric contractions. Effects of sodium hydrosulfide (NaHS), a donor of H(2)S, were evaluated on spontaneous contractile activity and after enhanced contractile activity with bethanechol. L-cysteine was evaluated as a potential endogenous donor of H(2)S. We evaluated involvement of extrinsic nerves, enteric nervous system, visceral afferent nerves, nitric oxide, and K(ATP)(+) channel and K(Ca)(+) channel activity on the action of H(2)S using non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, L-N(G)-nitro arginine (L-NNA), glibenclamide, and apamin, respectively, as well as electrical field stimulation.
  
  
  RESULTS
  NaHS dose-dependently and reversibly inhibited spontaneous and bethanechol-stimulated contractile activity (p < 0.05). L-cysteine had no inhibitory effect. Non-adrenergic/non-cholinergic conditions, tetrodotoxin, capsaicin, L-NNA, glibenclamide, or apamin had no major effect on total contractile activity by NaHS, although both tetrodotoxin and apamin decreased the frequency of bethanechol-enhanced contractile activity (p < 0.05). We could not demonstrate H(2)S release by electrical field stimulation but did show that inhibition of cystathionine β synthase, an endogenous source of H(2)S, augmented the inhibitory effect of low-frequency electrical field stimulation.
  
  
  CONCLUSIONS
  H(2)S inhibits contractile activity of ileal longitudinal muscle dose-dependently but not through pathways mediated by the extrinsic or enteric nervous system, visceral afferent nerves, nitric oxide, K(ATP)(+) channels, or K(Ca)(+) channels.
authors.affiliation: Gastroenterology Research Unit and Division of Gastroenterologic and General Surgery, Rochester, MN 55905, USA.
authors.forename: Munenori
authors.initials: M
authors.lastname: Nagao
authors.forename: David R
authors.initials: DR
authors.lastname: Linden
authors.forename: Judith A
authors.initials: JA
authors.lastname: Duenes
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sarr
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects / Q000502:physiology*; D054086:KATP Channels / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D054086:KATP Channels; D006862:Hydrogen Sulfide