title: Nitric oxide inhibits resting sphincter of Oddi activity.
abstract: The sphincter of Oddi has basal myogenic phasic activity that is modulated by neural and hormonal pathways. Stimulatory innervation to this organ is cholinergic, whereas the inhibitory pathways are unknown. Nitric oxide (NO), generated from L-arginine, relaxes gastrointestinal smooth muscle in vitro. We, therefore, hypothesized that resting sphincter of Oddi and duodenal motilities are regulated by a NO-mediated inhibitory pathway. In 23 anesthetized prairie dogs, systemic blood pressure and sphincter of Oddi and duodenal motilities were monitored during systemic infusion of N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase. L-NAME was infused alone and simultaneously with excess D- and L-arginine. L-NAME alone and L-NAME with D-arginine produced hypertension and increased sphincter of Oddi and duodenal motilities. L-arginine blocked these increases, suggesting that baseline sphincter of Oddi and duodenal motility regulation involves the generation of NO from L-arginine. We conclude that baseline sphincter of Oddi phasic activity is regulated by cholinergic stimulatory and NO-mediated inhibitory neural pathways.
authors.affiliation: Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: H S
authors.initials: HS
authors.lastname: Kaufman
authors.forename: M A
authors.initials: MA
authors.lastname: Shermak
authors.forename: C A
authors.initials: CA
authors.lastname: May
authors.forename: H A
authors.initials: HA
authors.lastname: Pitt
authors.forename: K D
authors.initials: KD
authors.lastname: Lillemoe
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000187:drug effects / Q000502:physiology; D005769:Gastrointestinal Motility / Q000187:drug effects; D008297:Male; D016065:Myoelectric Complex, Migrating / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase; D010275:Parasympathetic Nervous System / Q000502:physiology; D012589:Sciuridae; D009803:Sphincter of Oddi / Q000187:drug effects* / Q000294:innervation / Q000502:physiology
chemical_list: D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester