ENHANCING EFFECT OF PLATELETS ON STAPHYLOKINASE-MEDIATED CLOT LYSIS AND PLASMINOGEN ACTIVATION

The effects of platelets on clot lysis and plasminogen activation by s taphylokinase (SAK) were investigated. At concentrations ranging from 2 x 10(-7) to 1 x 10(-5)g/ml of SAK, the lysis time of platelet-rich p lasma clots (PRP-clots) was shorter than that of platelet-poor plasma clots (PPP-clots). This reduction of clot lysis time was observed in a dose-dependent manner on platelet count in PRP. The activation rate o f plasminogen by SAK measured by the amidolytic method using S-2251 wa s enhanced by the addition of washed platelets, These enhancing effect s of platelets on clot lysis and plasminogen activation were not alter ed by pretreatment of platelets with indometacin and theophylline, but were diminished by platelet disruption. Thus, we concluded that plate lets enhance fibrinolytic activity of SAK, and this effect is not due to the release reaction or intracellular contents of platelets, but to the existence of platelet surface in the intact shape as a catalytic site for fibrinolysis.