title: Heparin-induced release of extracellular superoxide dismutase to human blood plasma.
abstract: Extracellular superoxide dismutase (SOD) has previously been shown to be the major SOD isoenzyme in extracellular fluids. Upon chromatography on heparin-Sepharose it was separated into three fractions: A, without affinity; B, with intermediate affinity; and C, with relatively strong heparin affinity. Intravenous injection of heparin leads to a prompt increase in plasma extracellular-superoxide-dismutase (EC-SOD) activity. Heparin induces no release of EC-SOD from blood cells, nor does it activate EC-SOD in plasma, indicating that the source of the released enzyme is the endothelial-cell surfaces. No distinct saturation could be demonstrated in a dose-response curve up to 200 i.u. of heparin per kg body weight, showing that the releasing potency of heparin is lower for EC-SOD than for previously investigated heparin-released factors. Chromatography of human plasma on heparin-Sepharose shows nearly equal amounts of EC-SOD fractions A, B and C. Heparin induces specifically the release of fraction C. The findings point to the existence of an equilibrium of EC-SOD fraction C between the plasma phase and endothelial-cell surfaces. The major part of EC-SOD in the vasculature seems to be located on endothelial-cell surfaces.
mesh_terms: D002846:Chromatography, Affinity; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000097:blood* / Q000302:isolation & purification; D013482:Superoxide Dismutase / Q000097:blood* / Q000302:isolation & purification
chemical_list: D007527:Isoenzymes; D006493:Heparin; D013482:Superoxide Dismutase