The influence of various combinations of plasminogen and streptokinase on fibrinolysis.

The lysis rates of 125I cross-linked plasma fibrin clots have been investigated following immersion in various buffered concentration of streptokinase (SK), prior to (called the SK leads to plgn regimen) and after (called the plgn leads to SK regimen) enrichment with 2.0 U of plasminogen (plgn, lys-type). The SK leads to plgn regimen usually achieved total clot lysis with the most active lysis occurring following enrichment in 125-130 IU SK solutions, while only partial lysis was observed during the plgn leads to SK procedure. The effect of SK concentration was marked during the SK leads to plgn regimen while, during the plgn leads to SK treatment, its lytic rate never exceeded a factor of 2.0 over a wide concentration range of SK (8.0-20,000 IU/ml. The availability of plasminogen to perfuse the activator-rich clot seemed to be the prevailing influence on clot lysis and lysis of clots in plasma was inhibited by serum inhibitors, SK antibodies and plasma fibrinogen.