Antithrombotic effects of thrombin-induced activation of endogenous protein C in primates

Stephen R. Hanson, John H. Griffin, Laurence A. Harker, Andrew B. Kelly, Charles T. Esmon, András Gruber

Research output: Contribution to journalArticlepeer-review

170 Scopus citations


The effects on thrombosis and hemostasis of thrombin-induced activation of endogenous protein C (PC) were evaluated in baboons. Thrombosis was induced by placing into arteriovenous shunts a segment of Dacron vascular graft, which generated arterial platelet-rich thrombus, followed by an expansion region of low-shear blood flow, which in turn accumulated fibrin-rich venous-type thrombus. Thrombosis was quantified by 111In-platelet imaging and 125I-fibrinogen accumulation. Intravenous infusion of α-thrombin, 1-2 U / kg-min for 1 h, increased baseline activated PC levels (∼ 5 ng/ml) to 250-500 ng/ml (P < 0.01). The lower thrombin dose, which did not deplete circulating platelets, fibrinogen, or PC, reduced arterial graft platelet deposition by 48% (P < 0.05), and platelet and fibrin incorporation into venous-type thrombus by > 85% (P < 0.01). Thrombin infusion prolonged the activated partial thromboplastin clotting time, elevated fibrinopeptide A (FPA), thrombin antithrombin III complex (T:AT III), and fibrin D-dimer plasma levels (P < 0.01), but did not affect bleeding times. Thrombin's antithrombotic effects were blocked by infusing a monoclonal antibody (HPC-4) which prevented PC activation in vivo, caused shunt occlusion, increased the consumption of platelets and fibrinogen, elevated plasma FPA and T:AT III levels, and reduced factor VIII (but not factor V) procoagulant activity (P < 0.05). We conclude that activated PC is a physiologic inhibitor of thrombosis, and that activation of endogenous PC may represent a novel and effective antithrombotic strategy.

Original languageEnglish (US)
Pages (from-to)2003-2012
Number of pages10
JournalJournal of Clinical Investigation
Issue number4
StatePublished - 1993
Externally publishedYes


  • Anti-thrombotic therapy
  • Protein c
  • Thrombin
  • Thrombosis

ASJC Scopus subject areas

  • General Medicine


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