Abstract
The in vitro and in vivo combined effects of urinary plasminogen activator (u-PA) and tissue plasminogen activator (t-PA) were examined. In in vitro experiments the additive combined effects of u-PA and t-PA were observed on human plasma clot lysis. In in vivo studies using a canine coronary thrombus model, an intravenous combined administration of t-PA and u-PA synergistically enhanced their thrombolytic activity, while the reductions of fibrinogen, plasminogen and α2-plasmin inhibitor were additive.
The studies on plasma and blood dynamic viscosities revealed that whole blood dynamic viscosity decreased significantly in both u-PA and the combination groups, while plasma viscosity was not changed. This lowered blood viscosity was rather notable at the lower shear rate condition than at the higher shear rate. It is, therefore, presumed that this combination therapy may have a great advantage on thrombolysis in acute myocardial infarction.
