Bile: An emulsifying agent produced in the LIVER and secreted into the DUODENUM. Its composition includes BILE ACIDS AND SALTS; CHOLESTEROL; and ELECTROLYTES. It aids DIGESTION of fats in the duodenum.Bile Acids and Salts: Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones.Bile Ducts: The channels that collect and transport the bile secretion from the BILE CANALICULI, the smallest branch of the BILIARY TRACT in the LIVER, through the bile ductules, the bile ducts out the liver, and to the GALLBLADDER for storage.Common Bile Duct: The largest bile duct. It is formed by the junction of the CYSTIC DUCT and the COMMON HEPATIC DUCT.Bile Canaliculi: Minute intercellular channels that occur between liver cells and carry bile towards interlobar bile ducts. Also called bile capillaries.Bile Pigments: Linear TETRAPYRROLES that give a characteristic color to BILE including: BILIRUBIN; BILIVERDIN; and bilicyanin.Bile Duct Diseases: Diseases in any part of the ductal system of the BILIARY TRACT from the smallest BILE CANALICULI to the largest COMMON BILE DUCT.Bile Ducts, Intrahepatic: Passages within the liver for the conveyance of bile. Includes right and left hepatic ducts even though these may join outside the liver to form the common hepatic duct.Bile Duct Neoplasms: Tumors or cancer of the BILE DUCTS.Bile Ducts, Extrahepatic: Passages external to the liver for the conveyance of bile. These include the COMMON BILE DUCT and the common hepatic duct (HEPATIC DUCT, COMMON).Bile Reflux: Retrograde bile flow. Reflux of bile can be from the duodenum to the stomach (DUODENOGASTRIC REFLUX); to the esophagus (GASTROESOPHAGEAL REFLUX); or to the PANCREAS.Taurocholic Acid: The product of conjugation of cholic acid with taurine. Its sodium salt is the chief ingredient of the bile of carnivorous animals. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is used as a cholagogue and cholerectic.Chenodeoxycholic Acid: A bile acid, usually conjugated with either glycine or taurine. It acts as a detergent to solubilize fats for intestinal absorption and is reabsorbed by the small intestine. It is used as cholagogue, a choleretic laxative, and to prevent or dissolve gallstones.Cholic Acids: The 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholanic acid family of bile acids in man, usually conjugated with glycine or taurine. They act as detergents to solubilize fats for intestinal absorption, are reabsorbed by the small intestine, and are used as cholagogues and choleretics.Deoxycholic Acid: A bile acid formed by bacterial action from cholate. It is usually conjugated with glycine or taurine. Deoxycholic acid acts as a detergent to solubilize fats for intestinal absorption, is reabsorbed itself, and is used as a choleretic and detergent.Cholic Acid: A major primary bile acid produced in the liver and usually conjugated with glycine or taurine. It facilitates fat absorption and cholesterol excretion.Gallbladder: A storage reservoir for BILE secretion. Gallbladder allows the delivery of bile acids at a high concentration and in a controlled manner, via the CYSTIC DUCT to the DUODENUM, for degradation of dietary lipid.Cholestasis: Impairment of bile flow due to obstruction in small bile ducts (INTRAHEPATIC CHOLESTASIS) or obstruction in large bile ducts (EXTRAHEPATIC CHOLESTASIS).Cholelithiasis: Presence or formation of GALLSTONES in the BILIARY TRACT, usually in the gallbladder (CHOLECYSTOLITHIASIS) or the common bile duct (CHOLEDOCHOLITHIASIS).Lithocholic Acid: A bile acid formed from chenodeoxycholate by bacterial action, usually conjugated with glycine or taurine. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is used as cholagogue and choleretic.Ursodeoxycholic Acid: An epimer of chenodeoxycholic acid. It is a mammalian bile acid found first in the bear and is apparently either a precursor or a product of chenodeoxycholate. Its administration changes the composition of bile and may dissolve gallstones. It is used as a cholagogue and choleretic.Glycocholic Acid: The glycine conjugate of CHOLIC ACID. It acts as a detergent to solubilize fats for absorption and is itself absorbed.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Common Bile Duct Diseases: Diseases of the COMMON BILE DUCT including the AMPULLA OF VATER and the SPHINCTER OF ODDI.Enterohepatic Circulation: Recycling through liver by excretion in bile, reabsorption from intestines (INTESTINAL REABSORPTION) into portal circulation, passage back into liver, and re-excretion in bile.Taurodeoxycholic Acid: A bile salt formed in the liver by conjugation of deoxycholate with taurine, usually as the sodium salt. It is used as a cholagogue and choleretic, also industrially as a fat emulsifier.Taurochenodeoxycholic Acid: A bile salt formed in the liver by conjugation of chenodeoxycholate with taurine, usually as the sodium salt. It acts as detergent to solubilize fats in the small intestine and is itself absorbed. It is used as a cholagogue and choleretic.Biliary Tract: The BILE DUCTS and the GALLBLADDER.Cholesterol 7-alpha-Hydroxylase: A membrane-bound cytochrome P450 enzyme that catalyzes the 7-alpha-hydroxylation of CHOLESTEROL in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP7, converts cholesterol to 7-alpha-hydroxycholesterol which is the first and rate-limiting step in the synthesis of BILE ACIDS.Organic Anion Transporters, Sodium-Dependent: A subclass of ORGANIC ANION TRANSPORTERS whose transport of organic anions is driven either directly or indirectly by a gradient of sodium ions.Gallstones: Solid crystalline precipitates in the BILIARY TRACT, usually formed in the GALLBLADDER, resulting in the condition of CHOLELITHIASIS. Gallstones, derived from the BILE, consist mainly of calcium, cholesterol, or bilirubin.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Biliary Fistula: Abnormal passage in any organ of the biliary tract or between biliary organs and other organs.Cholagogues and Choleretics: Gastrointestinal agents that stimulate the flow of bile into the duodenum (cholagogues) or stimulate the production of bile by the liver (choleretic).Adenoma, Bile Duct: A benign tumor of the intrahepatic bile ducts.Cholecystectomy: Surgical removal of the GALLBLADDER.Cholestasis, Extrahepatic: Impairment of bile flow in the large BILE DUCTS by mechanical obstruction or stricture due to benign or malignant processes.Cholangiography: An imaging test of the BILIARY TRACT in which a contrast dye (RADIOPAQUE MEDIA) is injected into the BILE DUCT and x-ray pictures are taken.Common Bile Duct Neoplasms: Tumor or cancer of the COMMON BILE DUCT including the AMPULLA OF VATER and the SPHINCTER OF ODDI.Bilirubin: A bile pigment that is a degradation product of HEME.Cholangiopancreatography, Endoscopic Retrograde: Fiberoptic endoscopy designed for duodenal observation and cannulation of VATER'S AMPULLA, in order to visualize the pancreatic and biliary duct system by retrograde injection of contrast media. Endoscopic (Vater) papillotomy (SPHINCTEROTOMY, ENDOSCOPIC) may be performed during this procedure.Cholestanols: Cholestanes substituted in any position with one or more hydroxy groups. They are found in feces and bile. In contrast to bile acids and salts, they are not reabsorbed.Biliary Tract Diseases: Diseases in any part of the BILIARY TRACT including the BILE DUCTS and the GALLBLADDER.Cholestyramine Resin: A strongly basic anion exchange resin whose main constituent is polystyrene trimethylbenzylammonium Cl(-) anion.Cholestasis, Intrahepatic: Impairment of bile flow due to injury to the HEPATOCYTES; BILE CANALICULI; or the intrahepatic bile ducts (BILE DUCTS, INTRAHEPATIC).Hydroxysteroid Dehydrogenases: Enzymes of the oxidoreductase class that catalyze the dehydrogenation of hydroxysteroids. (From Enzyme Nomenclature, 1992) EC 1.1.-.Glycochenodeoxycholic Acid: A bile salt formed in the liver from chenodeoxycholate and glycine, usually as the sodium salt. It acts as a detergent to solubilize fats for absorption and is itself absorbed. It is a cholagogue and choleretic.Dehydrocholic Acid: A semisynthetic bile acid made from cholic acid. It is used as a cholagogue, hydrocholeretic, diuretic, and as a diagnostic aid.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Taurine: A conditionally essential nutrient, important during mammalian development. It is present in milk but is isolated mostly from ox bile and strongly conjugates bile acids.Taurolithocholic Acid: A bile salt formed in the liver from lithocholic acid conjugation with taurine, usually as the sodium salt. It solubilizes fats for absorption and is itself absorbed. It is a cholagogue and choleretic.Biliary Tract Surgical Procedures: Any surgical procedure performed on the biliary tract.Hepatic Duct, Common: Predominantly extrahepatic bile duct which is formed by the junction of the right and left hepatic ducts, which are predominantly intrahepatic, and, in turn, joins the cystic duct to form the common bile duct.Ligation: Application of a ligature to tie a vessel or strangulate a part.Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Cholangitis: Inflammation of the biliary ductal system (BILE DUCTS); intrahepatic, extrahepatic, or both.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Cholecystectomy, Laparoscopic: Excision of the gallbladder through an abdominal incision using a laparoscope.Cholestanetriol 26-Monooxygenase: An NAPH-dependent cytochrome P450 enzyme that catalyzes the oxidation of the side chain of sterol intermediates such as the 27-hydroxylation of 5-beta-cholestane-3-alpha,7-alpha,12-alpha-triol.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Jaundice, Obstructive: Jaundice, the condition with yellowish staining of the skin and mucous membranes, that is due to impaired BILE flow in the BILIARY TRACT, such as INTRAHEPATIC CHOLESTASIS, or EXTRAHEPATIC CHOLESTASIS.Symporters: Membrane transporters that co-transport two or more dissimilar molecules in the same direction across a membrane. Usually the transport of one ion or molecule is against its electrochemical gradient and is "powered" by the movement of another ion or molecule with its electrochemical gradient.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Micelles: Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.Steroid 12-alpha-Hydroxylase: A liver microsomal cytochrome P450 enzyme that catalyzes the 12-alpha-hydroxylation of a broad spectrum of sterols in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP8B1gene, converts 7-alpha-hydroxy-4-cholesten-3-one to 7-alpha-12-alpha-dihydroxy-4-cholesten-3-one and is required in the synthesis of BILE ACIDS from cholesterol.Hepatocytes: The main structural component of the LIVER. They are specialized EPITHELIAL CELLS that are organized into interconnected plates called lobules.Duodenum: The shortest and widest portion of the SMALL INTESTINE adjacent to the PYLORUS of the STOMACH. It is named for having the length equal to about the width of 12 fingers.Receptors, Cytoplasmic and Nuclear: Intracellular receptors that can be found in the cytoplasm or in the nucleus. They bind to extracellular signaling molecules that migrate through or are transported across the CELL MEMBRANE. Many members of this class of receptors occur in the cytoplasm and are transported to the CELL NUCLEUS upon ligand-binding where they signal via DNA-binding and transcription regulation. Also included in this category are receptors found on INTRACELLULAR MEMBRANES that act via mechanisms similar to CELL SURFACE RECEPTORS.Steroid Hydroxylases: Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism.Cholestanes: Derivatives of the saturated steroid cholestane with methyl groups at C-18 and C-19 and an iso-octyl side chain at C-17.Choledocholithiasis: Presence or formation of GALLSTONES in the COMMON BILE DUCT.Glucuronates: Derivatives of GLUCURONIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that include the 6-carboxy glucose structure.Cholates: Salts and esters of CHOLIC ACID.Sphincterotomy, Endoscopic: Incision of Oddi's sphincter or Vater's ampulla performed by inserting a sphincterotome through an endoscope (DUODENOSCOPE) often following retrograde cholangiography (CHOLANGIOPANCREATOGRAPHY, ENDOSCOPIC RETROGRADE). Endoscopic treatment by sphincterotomy is the preferred method of treatment for patients with retained or recurrent bile duct stones post-cholecystectomy, and for poor-surgical-risk patients that have the gallbladder still present.Cholangiocarcinoma: A malignant tumor arising from the epithelium of the BILE DUCTS.Sulfobromophthalein: A phenolphthalein that is used as a diagnostic aid in hepatic function determination.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Sterols: Steroids with a hydroxyl group at C-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. (IUPAC Steroid Nomenclature, 1987)Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Liver Diseases: Pathological processes of the LIVER.Drainage: The removal of fluids or discharges from the body, such as from a wound, sore, or cavity.Xanthomatosis: A condition marked by the development of widespread xanthomas, yellow tumor-like structures filled with lipid deposits. Xanthomas can be found in a variety of tissues including the SKIN; TENDONS; joints of KNEES and ELBOWS. Xanthomatosis is associated with disturbance of LIPID METABOLISM and formation of FOAM CELLS.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.CholanesLiver Cirrhosis, Biliary: FIBROSIS of the hepatic parenchyma due to obstruction of BILE flow (CHOLESTASIS) in the intrahepatic or extrahepatic bile ducts (BILE DUCTS, INTRAHEPATIC; BILE DUCTS, EXTRAHEPATIC). Primary biliary cirrhosis involves the destruction of small intra-hepatic bile ducts and bile secretion. Secondary biliary cirrhosis is produced by prolonged obstruction of large intrahepatic or extrahepatic bile ducts from a variety of causes.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Jaundice: A clinical manifestation of HYPERBILIRUBINEMIA, characterized by the yellowish staining of the SKIN; MUCOUS MEMBRANE; and SCLERA. Clinical jaundice usually is a sign of LIVER dysfunction.Ampulla of Vater: A dilation of the duodenal papilla that is the opening of the juncture of the COMMON BILE DUCT and the MAIN PANCREATIC DUCT, also known as the hepatopancreatic ampulla.Sphincter of Oddi: The sphincter of the hepatopancreatic ampulla within the duodenal papilla. The COMMON BILE DUCT and main pancreatic duct pass through this sphincter.Biliary Atresia: Progressive destruction or the absence of all or part of the extrahepatic BILE DUCTS, resulting in the complete obstruction of BILE flow. Usually, biliary atresia is found in infants and accounts for one third of the neonatal cholestatic JAUNDICE.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Jejunum: The middle portion of the SMALL INTESTINE, between DUODENUM and ILEUM. It represents about 2/5 of the remaining portion of the small intestine below duodenum.1-Naphthylisothiocyanate: A tool for the study of liver damage which causes bile stasis and hyperbilirubinemia acutely and bile duct hyperplasia and biliary cirrhosis chronically, with changes in hepatocyte function. It may cause skin and kidney damage.Eubacterium: A genus of gram-positive, rod-shaped bacteria found in cavities of man and animals, animal and plant products, infections of soft tissue, and soil. Some species may be pathogenic. No endospores are produced. The genus Eubacterium should not be confused with EUBACTERIA, one of the three domains of life.Cholesterol, Dietary: Cholesterol present in food, especially in animal products.ATP-Binding Cassette Transporters: A family of MEMBRANE TRANSPORT PROTEINS that require ATP hydrolysis for the transport of substrates across membranes. The protein family derives its name from the ATP-binding domain found on the protein.Cholestanol: A cholesterol derivative found in human feces, gallstones, eggs, and other biological matter.Cholestenones: CHOLESTENES with one or more double bonds and substituted by any number of keto groups.