title: Affinity of binding of radiolabeled (125I) heparin and low molecular weight heparin fraction CY 222 to endothelium in culture.
abstract: Binding of radiolabeled (125I) heparin and its low molecular weight fraction CY 222 (Choay) to human and porcine cultured endothelium was investigated. The binding was measured over a wide range of heparin or CY 222 concentration in culture medium, from less than 20-time up to more than 30-times of the therapeutic heparin level. A relatively small fraction (less than 1%) of tested products was bound to endothelium. The process of binding was temperature-independent. A comparable number of endothelial binding sites (approx. 10(12)/cm2) for both 125I-heparin and 125I-CY 222 was calculated. About 40% totally bound 125I-heparin and 30% of 125I-CY 222 was found in extracellular matrix of cultured endothelium. The endothelium exhibited a 2.4-times lower affinity for 125I-CY 222 (Kd = 5.59 +/- 1.77 microM) than that for 125I-heparin (Kd = 2.35 +/- 0.78 microM). A similar affinity of human (venous) and porcine (aortic) endothelium for 125I-heparin was demonstrated. Cultured endothelium exhibited the same affinity for unlabeled heparin as for 125I-heparin. The endothelium depleted of sialic acid residues bound 1.5-times more of 125I-CY 222 than the control endothelium in culture.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism*; D006495:Heparin, Low-Molecular-Weight / Q000378:metabolism*; D006801:Humans; D007457:Iodine Radioisotopes; D012044:Regression Analysis; D013552:Swine
chemical_list: D006495:Heparin, Low-Molecular-Weight; D007457:Iodine Radioisotopes; D006493:Heparin