title: Plasma bikunin: half-life and tissue uptake.
abstract: Bikunin is a chondroitin sulfate-containing plasma protein synthesized in the liver. In vitro, it has been shown to inhibit proteases and to have additional activities, but its biological function is still unclear. Here we have studied the dynamics of plasma bikunin in rats and mice. A half-life of 7 +/- 2 min was obtained from the time course of the decrease of the plasma level of bikunin following hepatectomy. Clearance experiments with intravenously injected radiolabeled bikunin with or without the chondroitin sulfate chain showed that the polysaccharide had little influence on the elimination rate of the protein. The uptake of bikunin by different tissues was studied using bikunin labeled with the residualizing agent 125I-tyramine cellobiose; 60 min after intravenous injection, 49% of the radioactivity was recovered in the kidneys and 6-11% in the liver, bones, skin, intestine and skeletal muscle. The uptake in the liver was analyzed by intravenous injection of radiolabeled bikunin followed by collagenase perfusion and dispersion of the liver cells. These experiments indicated that bikunin is first trapped extracellularly within the liver before being internalized by the cells.
authors.affiliation: Department of Medical Biochemistry and Microbiology Uppsala University, Biomedical Center, Uppsala, Sweden.
authors.forename: Aneta
authors.initials: A
authors.lastname: Kaczmarczyk
authors.forename: Anna M
authors.initials: AM
authors.lastname: Blom
authors.forename: James
authors.initials: J
authors.lastname: Alston-Smith
authors.forename: Mats
authors.initials: M
authors.lastname: Sjöquist
authors.forename: Erik
authors.initials: E
authors.lastname: Fries
mesh_terms: D000818:Animals; D002475:Cellobiose / Q000737:chemistry; D002809:Chondroitin Sulfates / Q000737:chemistry / Q000378:metabolism; D006207:Half-Life; D006498:Hepatectomy; D007275:Injections, Intravenous; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics*; D008657:Metabolic Clearance Rate; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000008:administration & dosage / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics*; D014439:Tyramine / Q000737:chemistry
chemical_list: D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; C109148:SPINT2 protein, human; C038394:tyramine-cellobiose adduct; D002475:Cellobiose; D002809:Chondroitin Sulfates; D014360:Trypsin Inhibitor, Kunitz Soybean; D014439:Tyramine