title: Localization and characterization of secretin binding sites expressed by rat bile duct epithelium.
abstract: The goal of the present studies was to identify and characterize the site of secretin action in the liver. Sections of normal and bile duct-ligated rat livers were used for in vitro 125I-secretin receptor autoradiography. Saturable binding was observed in both normal and bile duct-ligated livers but was much greater in the bile duct-ligated preparations. Binding was limited to biliary epithelium and the increased secretin binding observed in the ligated livers correlated with the increase in ductular tissue. Saturable binding was inhibited in a dose-dependent fashion by increasing concentrations of nonradioactive secretin. Analysis of saturation binding showed that 125I-secretin binding was best fit by a one-site receptor model with a Kd of 5.3 +/- 1.1 nmol/L. Glucagon, vasoactive intestinal polypeptide, gastric inhibitory polypeptide, growth hormone-releasing hormone, and cholecystokinin did not inhibit saturable 125I-secretin binding at concentrations of 1 pmol/L to 1 mumol/L. The authors conclude that high-affinity, specific secretin binding sites are present in rat intrahepatic biliary epithelium. When bile ducts are stimulated to proliferate by bile duct ligation, secretin binding is also increased.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: M
authors.initials: M
authors.lastname: Farouk
authors.forename: S R
authors.initials: SR
authors.lastname: Vigna
authors.forename: D C
authors.initials: DC
authors.lastname: McVey
authors.forename: W C
authors.initials: WC
authors.lastname: Meyers
mesh_terms: D000818:Animals; D001345:Autoradiography; D001652:Bile Ducts / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D002766:Cholecystokinin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000378:metabolism; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology; D005934:Glucagon / Q000494:pharmacology; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D006965:Hyperplasia / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone / Q000096:biosynthesis*; D012633:Secretin / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; C029937:secretin receptor; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; D005749:Gastric Inhibitory Polypeptide; D005934:Glucagon; D002766:Cholecystokinin; D013007:Growth Hormone-Releasing Hormone