title: [Effects of methane on proximal colon motility of rats and ion channel mechanisms].
abstract: OBJECTIVE
  To explore the effects of methane on proximal colon motility and elucidate its ion channel mechanisms.
  
  
  METHODS
  The circular muscle and longitudinal muscle strips of proximal colon were isolated from rats. An isometric force transducer and a biology signal collection system were employed to observe the effects of methane on spontaneous contractile activity of muscle strips. The effects of methane on longitudinal muscle strips were observed after pre-treatment of these strips with tetrodotoxin (TTX) or N-nitro-L-arginine methylester (L-NAME). Single cell of colonic smooth muscle was isolated by collagenase and then whole-cell patch clamp technique was used to record voltage dependent potassium current (IKV) and large conductance Ca(2+)-activated K(+) current (IBKca) in the absence or presence of methane.
  
  
  RESULTS
  Methane significantly attenuated the contractile amplitude of longitudinal muscle strips (from (1.12 ± 0.27) to (0.99 ± 0.31) g, n = 19, P = 0.013) whereas there were no changes in some longitudinal muscle strips (n = 6) in the presence of methane. The inhibitory effect of methane persisted after the pre-treatment of longitudinal muscle strips with TTX or L-NAME. Methane had no effects on the contractile cycle time of longitudinal muscle strips and contractile activity of circular muscle strips. And 3% methane solution significantly increased the density of IKV (from (13.3 ± 1.0) pA/pF to (18.5 ± 1.4) pA/pF, at +60 mV, n = 11, P = 0.001) versus the control group whereas methane had no effect on IBKca (all P > 0.05).
  
  
  CONCLUSIONS
  Methane can inhibit contractile activity of proximal colonic longitudinal muscle by activating voltage dependent potassium channel and increasing IKV.
authors: Department of Gastroenterology, Renmin Hospital, Wuhan University, Wuhan, China.
authors: Ying
authors: Y
authors: Liu
authors: He-sheng
authors: HS
authors: Luo
authors: Cheng-bo
authors: CB
authors: Liang
authors: Wei
authors: W
authors: Tan
authors: Hong
authors: H
authors: Xia
authors: Wen-juan
authors: WJ
authors: Xu
mesh_terms: D000818:Animals; D003106:Colon / Q000187:drug effects* / Q000502:physiology; D005769:Gastrointestinal Motility; D066298:In Vitro Techniques; D008297:Male; D008697:Methane / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D024642:Potassium Channels, Voltage-Gated; D008697:Methane