1. Somatostatin stimulates the brush-tailed possum sphincter of Oddi in vitro and in vivo.
- Author
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Huang J, Padbury RT, Schloithe AC, Cox MR, Simula ME, Harvey JR, Baker RA, Toouli J, and Saccone GT
- Subjects
- Animals, Australia, Common Bile Duct cytology, Common Bile Duct innervation, Female, Fluorescent Antibody Technique, Gallbladder cytology, Gallbladder innervation, Ganglia, Sympathetic cytology, In Vitro Techniques, Male, Muscle Contraction drug effects, Muscle, Smooth drug effects, Muscle, Smooth innervation, Muscle, Smooth physiology, Nerve Fibers ultrastructure, Neurons physiology, Opossums, Somatostatin analysis, Sphincter of Oddi drug effects, Sphincter of Oddi innervation, Tetrodotoxin pharmacology, Neurons cytology, Somatostatin pharmacology, Somatostatin physiology, Sphincter of Oddi physiology
- Abstract
Background & Aims: Somatostatin, a neuropeptide and hormone, is found in the biliary tract of several species. The aim of this study was to map the distribution of somatostatin-like immunoreactive nerve fibers in the extrahepatic biliary tract of the Australian possum and to determine the pharmacological effects of somatostatin 1-14 on sphincter of Oddi activity in vitro and in vivo., Methods: Tissue was harvested for immunohistochemistry and sphincter of Oddi for circular or longitudinal muscle contractility. In anesthetized possums, sphincter of Oddi motility was measured by manometry, and transsphincteric flow was measured gravimetrically., Results: Somatostatin immunoreactivity was evident in gallbladder ganglia nerve cell bodies and in nerve fibers of the common bile duct and sphincter of Oddi. Somatostatin 1-14 increased circular and longitudinal muscle contraction amplitude 3-4-fold (P < 0.05), but only the longitudinal muscle contraction amplitude was tetrodotoxin sensitive. Somatostatin 1-14 stimulated spontaneous sphincter of Oddi motility in a tetrodotoxin-insensitive manner, increasing basal pressure, contraction frequency, and amplitude 2-4-fold (P < 0.05) and reducing transsphincteric flow to 25% of control (P < 0.0001)., Conclusions: Somatostatin-like immunoreactivity is present in the extrahepatic biliary tree, and somatostatin 1-14 stimulates sphincter of Oddi smooth muscle and nerves. The major action is direct stimulation of sphincter of Oddi circular muscle, which reduces transsphincteric flow.
- Published
- 1998
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