Catalytic activity and integrity of plasma scuPA/suPAR complexes. (A) Lysis of fibrinogen: ¹²⁵I-fibrinogen was injected intravenously immediately before injecting saline alone (Cont.) or saline containing 11.3 mg/kg scuPA or the scuPA/suPAR complex. Two hours later, blood was collected, plasma prepared, and the release of radiolabeled fibrinogen degradation products (FDPs) into the plasma was measured. (B) Lysis of plasma clots: 11.3 mg/kg scuPA or scuPA/suPAR was injected; 2 minutes later, blood was collected, plasma prepared, and the capacity of the plasma from control animals (Cont.) or those injected with scuPA or scuPA/suPAR to lyse ¹²⁵I-plasma clots was measured. (C) ¹²⁵I-scuPA or ¹²⁵I-scuPA/suPAR complex (11.3 mg/kg) was injected intravenously. Two minutes later blood was taken, plasma prepared, and plasma radioactivity was precipitated using anti-uPAR antibodies. In all panels, results from 4 mice (mean ± SD) are shown.