title: Supersaturation of canine gallbladder bile with calcium bilirubinate during formation of pigment gallstones.
abstract: Analogous to cholesterol gallstones forming in bile supersaturated with cholesterol, pigment gallstones may form in bile supersaturated with calcium bilirubinate. We tested this hypothesis in a dietary model of pigment gallstones. The concentration of ionized calcium (Ca++) and unconjugated bilirubin (UCB) was measured in 15 normal dogs and in 15 dogs with pigment gallstones induced by 6 weeks of a methionine-deficient diet. Although there was minimal change in the gallbladder's ability to acidify or concentrate bile, both [Ca++] and [UCB] markedly increased. These values were compared with equilibrium concentrations in model bile solutions. In all normal bile, the [UCB] was equal to or lower than the mean [UCB] concentration of model bile solutions with comparable [Ca++]. However, in all but one bile sample from dogs with pigment gallstones, the [UCB] exceeded this concentration and was therefore supersaturated with calcium bilirubinate. This supports the hypothesis that calcium bilirubinate precipitation is important in the formation and growth of pigment gallstones.
authors.affiliation: Department of Surgery, Veterans Administration Lakeside Medical Center, Chicago, Illinois.
authors.forename: L G
authors.initials: LG
authors.lastname: Dawes
authors.forename: D L
authors.initials: DL
authors.lastname: Nahrwold
authors.forename: R V
authors.initials: RV
authors.lastname: Rege
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000378:metabolism; D001663:Bilirubin / Q000378:metabolism*; D002769:Cholelithiasis / Q000378:metabolism*; D004285:Dogs; D005704:Gallbladder / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008715:Methionine / Q000008:administration & dosage; D012964:Sodium / Q000378:metabolism
chemical_list: D001647:Bile Acids and Salts; D012964:Sodium; D008715:Methionine; D001663:Bilirubin