title: Affects of hirudin and heparin on the binding of new fibrin to the thrombus in t-PA treated rabbits.
abstract: The aim of this study was to compare the ability of heparin and recombinant hirudin (r-hirudin) in preventing accretion of new fibrin on thrombi during and after treatment with tissue-type plasminogen activator (t-PA) and in enhancing t-PA induced fibrinolysis in a rabbit jugular vein thrombosis model. Heparin and r-hirudin were infused at doses capable of doubling aPTT. In the fibrin accretion inhibition experiments t-PA was infused over 3 h at a dose of 0.2 mg/kg along with saline or heparin, 0.75 mg/kg or r-hirudin, 1.25 mg/kg. In rabbits treated with t-PA plus saline, heparin or r-hirudin, an accumulation of 125I-fibrinogen on the thrombi of 52.5 +/- 5.1 micrograms, 49.5 +/- 5.6 micrograms and 23.5 +/- 3.5 micrograms was observed, respectively, the difference between r-hirudin and both saline and heparin being statistically significant (p less than 0.01). The inhibition of fibrin accretion on the thrombi induced by r-hirudin persists for at least 9 h after the end of the infusion. By that time r-hirudin has been cleared from the circulation and aPTT has returned to the baseline level for at least 8 h. t-PA, 0.2, 0.4, and 1 mg/kg, infused with saline produced 34 +/- 6%, 52 +/- 5% and 79 +/- 8% lysis of pre-formed thrombi, respectively. The same doses of t-PA infused with heparin, 0.75 mg/kg, produced 32 +/- 3%, 54 +/- 5% and 78 +/- 6% fibrinolysis, respectively and infused with r-hirudin, 1.25 mg/kg, 38 +/- 3%, 57 +/- 5% and 82 +/- 8%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Istituto di Semeiotica Medica, Università di Perugia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Agnelli
authors.forename: C
authors.initials: C
authors.lastname: Pascucci
authors.forename: B
authors.initials: B
authors.lastname: Cosmi
authors.forename: G G
authors.initials: GG
authors.lastname: Nenci
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects*; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005341:Fibrinolysin / Q000378:metabolism; D005342:Fibrinolysis / Q000187:drug effects*; D006493:Heparin / Q000494:pharmacology*; D006629:Hirudins / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides; D011817:Rabbits; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*
chemical_list: D006629:Hirudins; D009842:Oligopeptides; D005337:Fibrin; D005340:Fibrinogen; D006493:Heparin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin