Summary
We investigated the effect of staphylokinase (SAK), which has specific thrombolytic
properties, on human platelet aggregation. Platelet aggregation induced with collagen
was observed following preincubation of platelets in platelet-rich plasma (PRP) or
washed platelet suspension (WP) with SAK at 37° C for 30 min. SAK inhibited platelet
aggregation in PRP only at the highest examined concentration (1 x 10-4 g/ml). Although SAK did not inhibit platelet aggregation in WP which contained fibrinogen,
it did when the platelets had been preincubated with SAK and plasminogen. The most
effective concentration in WP was 1 x 10-6 g/ml. The effect could be inhibited by adding aprotinin or α2-antiplasmin. The highest generation of plasmin in the same preincubation fluid was
detected at 1 x 10-6 g/ml SAK. We concluded that SAK can inhibit platelet aggregation in WP by generating
plasmin and/or fibrinogen degradation products, but is only partially effective in
PRP because of the existence of α2-antiplasmin.
