PLASMINOGEN DEPLETION DURING STREPTOKINASE TREATMENT OR 2-CHAIN UROKINASE INCUBATION CORRELATES WITH DECREASED CLOT LYSABILITY EX-VIVO AND IN-VITRO

The relationship between lytic state variables and ex vivo clot lysabi lity was investigated in blood drawn from patients during streptokinas e administration for acute myocardial infarction. A lytic state was al ready evident after 5 min of treatment and after 20 min the plasminoge n concentration had decreased to 24%, antiplasmin to 7% and fibrinogen 0.2 g/l. Lysis of radiolabeled retracted clots in the patient plasmas decreased from 37 +/- 8% after 5 min to 21 +/- 8% at 10 min and was s ignificantly lower (8 +/- 9%, p <0.005) in samples drawn at 20, 40 and 80 min. Clot lysability correlated positively with the plasminogen co ncentration (r = 0.78, p = 0.003), but not with plasmin activity. Susp ension of radiolabeled clots in normal plasma pre-exposed to 250 U/ml two-chain urokinase for varying time to induce an in vitro lytic state was also associated with decreasing clot lysability in direct proport ion with the duration of prior plasma exposure to urokinase. The decre ased lysability correlated with the time-dependent reduction in plasmi nogen concentration (r = 0.88, p <0.0005). Thus, clot lysability decre ases in conjunction with the development of the lytic state and the as sociated plasminogen depletion. The lytic state may therefore limit re perfusion during thrombolytic treatment.