[Intensification of the effect of exogenous plasminogen activators on lysis of fibrin blood clots due to a decrease...

Using plasminogen-Sepharose 4B chromatography, a 50-70% reduction in the alpha-2-antiplasmin (alpha-2-AP) content in human and dog blood plasma was reached. The decrease in the alpha-2-AP concentration in human and dog blood plasma markedly enhanced the lysis of fibrin clots formed from the plasma under the action of urokinase and streptokinase. Thus, the lysis of model clots for a definite period of time for human and dog blood plasma depleted for alpha-2-AP by 50-70% required 5-8 and 3-6 times as low urokinase and streptokinase concentrations as those needed for the clot lysis in the native plasma. The decrease in the fibrinogen concentration in human blood plasma caused by plasmosorption on plasminogen-Sepharose enhanced the model fibrin clot lysis by urokinase and streptokinase, however, by no more than 5-10%. Hence, the increased efficiency of plasminogen activators in the given model system can be accounted for by the decline of the antiplasmin potential of the blood plasma.