The role of antioxidant enzymes in the control of opossum sphincter of Oddi motility

Joseph J. Cullen, Brian M. Herrmann, Raymond M. Thomas, Shengyun Fang, Joseph A. Murray, Amber Ledlow, James Christensen, Jeffrey L. Conklin

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)G1050-G1056
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number5 35-5
StatePublished - May 1997


  • Contractile activity
  • Enzyme activity
  • Immunostaining
  • Nitric oxide
  • Oxygen free radicals
  • Superoxide dismutase

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)


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