Effect of activation of the fibrinolytic mechanism on experimental platelet-rich thrombi in rabbits.

Abstract

Abstract Activation of the fibrinolytic mechanism was found to suppress the formation of thrombi in extracorporeal shunts connected to rabbits. The effect of increased fibrinolytic activity on the dissolution of established platelet-rich thrombi was also examined. Streptokinase infusions resulted in a considerable reduction in thrombus size but were also associated with a high incidence of death, apparently caused by diffuse pulmonary platelet-rich microemboli originating from the breaking up of the established thrombi. Urokinase infusion, in contrast to streptokinase, actually enhanced thrombus formation in rabbits. This thrombus augmenting effect appeared to be attributable to the presence of contaminating clot promoting activity in the urokinase which became apparent because of the high concentrations of urokinase required to activate the fibrinolytic system in rabbits.