Thrombin Binds to Soluble Fibrin Degradation Products Where it Is Protected From Inhibition by Heparin-Antithrombin but Susceptible to Inactivation by Antithrombin-Independent Inhibitors

BACKGROUND: Thrombolytic therapy induces a procoagulant state characterized by elevated plasma levels of fibrinopeptide A (FPA), but the responsible mechanism is uncertain. METHODS AND RESULTS: Washed plasma clots were incubated in citrated plasma in the presence or absence of tissue plasminogen activator (t-PA), and FPA generation was monitored as an index of unopposed thrombin activity. FPA levels are almost twofold higher in the presence of …