title: Studies on the mechanisms of biliary excretion of circulating glycoproteins. The carcinoembryonic antigen.
abstract: The transport of carcinoembryonic antigen from the circulation of the bile has been studied in the rat. Biliary excretion was directly proportional to the intravenously administered dose. Approximately 1-1.5% of the injected is excreted in the bile. Asialo-(carcinoembryonic antigen), asialo-fetuin and asialo-(alpha 1-acid glycoprotein) behaved similarly. The transit time through the liver for both native- and asialo-(carcinoembryonic antigen) was calculated as 47 min. Sialic acid content was not affected during biliary excretion. Glycoproteins that entered the liver cell lysosomes were not excreted in ther bile. A mechanism by which circulating proteins may by-pass the hepatocytes before being excreted in bile is suggested. Alternative mechanisms of protein entry into bile are discussed.
mesh_terms: D000818:Animals; D001212:Asialoglycoproteins; D001646:Bile / Q000276:immunology / Q000378:metabolism*; D001692:Biological Transport; D002241:Carbohydrates / Q000032:analysis; D002272:Carcinoembryonic Antigen / Q000031:analogs & derivatives* / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D060748:Fetuins; D006023:Glycoproteins / Q000378:metabolism*; D008297:Male; D009961:Orosomucoid / Q000031:analogs & derivatives / Q000032:analysis; D051381:Rats; D013997:Time Factors; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D001212:Asialoglycoproteins; D002241:Carbohydrates; D002272:Carcinoembryonic Antigen; D060748:Fetuins; D006023:Glycoproteins; D009961:Orosomucoid; D000509:alpha-Fetoproteins; C029935:asialo-carcinoembryonic antigen; C017029:asialofetuin; C017030:asialoorosomucoid