title: The role of antioxidant enzymes in the control of opossum sphincter of Oddi motility.
abstract: Superoxide rapidly oxidizes nitric oxide (NO) to form peroxynitrite, thus terminating the biological activity of NO. The aims of our study were to determine if superoxide alters the motor function of the sphincter of Oddi and to localize the antioxidant enzymes in the sphincter of Oddi. Immunostaining was performed and enzyme activities were measured in the sphincter of Oddi. In physiological experiments, force-displacement transducers recorded tension in the spontaneously contracting sphincter of Oddi and after electrical field stimulation (EFS) of precontracted sphincter of Oddi. Superoxide was generated by the addition of xanthine with xanthine oxidase, superoxide radicals were scavenged by the addition of superoxide dismutase (SOD), and catalase or SOD was inhibited by diethyldithiocarbamic acid. Immunostaining demonstrated SOD and catalase immunoreactivity in ganglia situated at the serosal surface of the circular muscle. Total SOD activity was 202 +/- 12 U/mg. Generation of superoxide or inhibition of SOD increased the contractile frequency and decreased relaxation after EFS. We conclude that superoxide alters sphincter of Oddi motor function, and the presence of superoxide scavenging enzymes in enteric plexuses suggests that they may regulate sphincter of Oddi neuromuscular function by clearing endogenous superoxide.
authors.affiliation: Department of Surgery, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Cullen
authors.forename: B M
authors.initials: BM
authors.lastname: Herrmann
authors.forename: R M
authors.initials: RM
authors.lastname: Thomas
authors.forename: S
authors.initials: S
authors.lastname: Fang
authors.forename: J A
authors.initials: JA
authors.lastname: Murray
authors.forename: A
authors.initials: A
authors.lastname: Ledlow
authors.forename: J
authors.initials: J
authors.lastname: Christensen
authors.forename: J L
authors.initials: JL
authors.lastname: Conklin
mesh_terms: D000818:Animals; D002374:Catalase / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D009119:Muscle Contraction; D009126:Muscle Relaxation / Q000502:physiology; D009420:Nervous System / Q000378:metabolism; D009424:Nervous System Physiological Phenomena; D009893:Opossums; D009803:Sphincter of Oddi / Q000294:innervation / Q000502:physiology*; D013482:Superoxide Dismutase / Q000502:physiology*
chemical_list: D002374:Catalase; D013482:Superoxide Dismutase