Different effect of 5,6-trans-prostaglandin E2 on plasminogen activation by urokinase and streptokinase

We examined the effects of 5,6-trans-prostaglandin E2 (trans-PG E2) on fibrinolysis and plasminogen activation by either urokinase or streptokinase. trans-PG E2 was found to enhance fibrinolysis induced by urokinase and inhibit the one by streptokinase. These effects were also appeared in the method using synthetic chromogenic substrate S-2251, which suggested that the effects of trans-PG E2 were induced in the circumstances without coagulation factors such as fibrinogen, thrombin or fibrin. Moreover, the enhancement effect of trans-PG E2 on fibrinolysis by urokinase was investigated. The result of SDS-PAGE indicated that plasmin formation rate from plasminogen by urokinase was accelerated in the presence of trans-PG E2. As trans-PG E2 increased the hydrolyzing rate of S-2288 by urokinase, trans-PG E2 directly interacted with urokinase. Therefore, the enhancement effect of trans-PG E2 on plasminogen activation by urokinase could be explained, at least in part, as follows: at first trans-PG E2 directly exerts its effect on urokinase, then it causes the increase of generation rate of plasmin from plasminogen.