title: Altered gallbladder bile acidification with long-term total parenteral nutrition.
abstract: BACKGROUND
  An important function of the gallbladder is to acidify and concentrate bile. Acidification helps protect against the precipitation of calcium salts, which promote gallstone formation. Altered acidification may result in pigment gallstones. We investigated gallbladder composition in a model of TPN-associated pigment gallstones to test whether changes in acidification may be important in this gallstone model.
  
  
  METHODS
  Ten miniswine were intravenously fed for 21 to 27 days (mean 23 days). Ten fed pig chow with intravenous infusion of saline served as controls. Gallbladder and hepatic bile electrolytes, lipids, pH, and pCO2 were measured.
  
  
  RESULTS
  All animals remained healthy and gained weight. Hepatic bile electrolytes and pH were similar among all animals. Pigs on TPN had a higher gallbladder pH and the [H+] was half the value of controls [8.1 +/- 1.6 x 10(-8) meq/liter (control) versus 3.9 +/- 0.7 x 10(-8) meq/liter (TPN)]. Gallbladder bile pCO2, sodium (Na), and potassium were higher in controls. Biliary lipids [bile salts (BS), phospholipids, and cholesterol] with TPN were decreased in both hepatic and gallbladder bile.
  
  
  CONCLUSIONS
  Unlike short-term TPN where gallbladder pH and [BS] are similar, with long-term TPN pH is higher with lower [H+], [Na], and [BS]. Despite a presumed longer residence time in the gallbladder, intravenous feeding without oral intake results in gallbladder bile that is less concentrated and acidified. Enteral stimulation may be an important stimulus for gallbladder acidification and periods without feeding may promote gallstone formation by increasing the pH of gallbladder bile.
authors.affiliation: Northwestern University, Chicago, Illinois, 60611, USA.
authors.forename: L G
authors.initials: LG
authors.lastname: Dawes
authors.forename: M
authors.initials: M
authors.lastname: Greiner
authors.forename: R J
authors.initials: RJ
authors.lastname: Joehl
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry*; D001647:Bile Acids and Salts / Q000032:analysis; D001653:Bile Ducts, Intrahepatic / Q000378:metabolism; D002245:Carbon Dioxide / Q000032:analysis; D002769:Cholelithiasis / Q000209:etiology*; D002784:Cholesterol / Q000032:analysis; D005704:Gallbladder / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010289:Parenteral Nutrition, Total / Q000009:adverse effects*; D010743:Phospholipids / Q000032:analysis; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013552:Swine; D013556:Swine, Miniature
chemical_list: D001647:Bile Acids and Salts; D010743:Phospholipids; D002245:Carbon Dioxide; D002784:Cholesterol; D012964:Sodium; D011188:Potassium