Incorporation of ALA-14C in circulating bilirubin and hemoglobin heme of hepatectomized dogs.
After intravenous injection of delta amino-levulinic acid-14C (ALA-14C) (50 muCi) in hepatectomized dogs, bilirubin-14C reaches a peak after 3-6 hours and then slowly falls. During this time radioactivity of hemoglobin heme is much lower and rises sluggishly. Bilirubin specific activity is several hundred times that of hemoglobin heme. Incorporation of isotope is also much greater for bilirubin. This difference between bilirubin-14C and hemoglobin heme-14C provides evidence that bilirubin is produced outside the liver by a mechanism other than breakdown of hemoglobin. In intact dogs with cannulated common duct, intravenous injection of ALA-14C produces similar results but the rise of bilirubin-14C produced in 9 hours in the hepatectomized dogs is about 12% of the total blood bilirubin-14C of non hepatectomized animals with cannulated common duct. If we include bile bilirubin-14C produced in the same time by intact animals with cannulated common duct, nonhemoglobin bile production is only 4.2% of the total.
D000622:Aminolevulinic Acid / Q000378:metabolism; D000818:Animals; D001663:Bilirubin / Q000096:biosynthesis*; D004285:Dogs; D006418:Heme / Q000031:analogs & derivatives*; D006427:Hemin / Q000096:biosynthesis*; D006454:Hemoglobins / Q000378:metabolism; D006498:Hepatectomy; D008099:Liver / Q000378:metabolism
D006454:Hemoglobins; D006418:Heme; D006427:Hemin; D000622:Aminolevulinic Acid; D001663:Bilirubin