title: Mechanism of interdigestive migrating motor complex in conscious dogs.
abstract: BACKGROUND
  The migrating motor complex (MMC) is well characterized by the appearance of gastrointestinal contractions in the interdigestive state. This study was designed to clarify the mechanisms of gastric MMC (G-MMC) and intestinal MMC (I-MMC) in conscious dogs.
  
  
  METHODS
  Five strain gauge transducers were implanted on the stomach and intestine. To investigate the correlation between luminal 5-HT and phase III contractions, gastric and duodenal juices were collected during the MMC cycle. The 5-HT concentrations in gastric and duodenal juice were measured by HPLC. To investigate whether luminal 5-HT initiates MMC, 5-HT (10(-8)-10(-6) M, 10 ml) was administered into the duodenum 20 min after gastric phase III. To investigate the involvement of 5-HT(3) or 5-HT(4) receptors in mediating G-MMC and I-MMC, 5-HT(3) antagonists (ondansetron) or 5-HT(4) antagonists (GR 125,487) were infused for 120 min.
  
  
  RESULTS
  Luminal administration of 5-HT (10(-6) M) initiated duodenal phase II followed by G-MMC and I-MMC with a concomitant increased release of plasma motilin. The duodenal 5-HT concentration was significantly increased during phase II (59 +/- 9 ng/ml) and phase III (251 +/- 21 ng/ml) compared to that of phase I (29 +/- 5 ng/ml). On the other hand, the 5-HT content in the stomach was not significantly changed throughout the MMC cycle. Intravenous infusion of motilin (0.3 microg/kg/h) increased the luminal 5-HT content and induced G-MMC and I-MMC. 5-HT(4) antagonists significantly inhibited both G-MMC and I-MMC, while 5-HT(3) antagonists inhibited only G-MMC.
  
  
  CONCLUSIONS
  It is suggested that the MMC cycle is mediated by a positive feedback mechanism via the interaction between motilin and 5-HT.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC, USA.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakajima
authors.forename: Erito
authors.initials: E
authors.lastname: Mochiki
authors.forename: Aaron
authors.initials: A
authors.lastname: Zietlow
authors.forename: Kirk
authors.initials: K
authors.lastname: Ludwig
authors.forename: Toku
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D003243:Consciousness / Q000502:physiology; D004285:Dogs; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D005765:Gastrointestinal Agents / Q000494:pharmacology; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D009037:Motilin / Q000494:pharmacology / Q000502:physiology*; D009092:Mucous Membrane / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D016065:Myoelectric Complex, Migrating / Q000187:drug effects / Q000502:physiology*; D011706:Pyloric Antrum / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D018490:Serotonin Agents / Q000494:pharmacology; D014160:Transducers, Pressure
chemical_list: D005765:Gastrointestinal Agents; D018490:Serotonin Agents; D012701:Serotonin; D009037:Motilin