Method of estimating the inhibitory effect of plasma or serum upon urokinase-activated fibrinolysis.

Activator concentration in the range 50 to 100 Ploug units urokinase is directly proportional to the reciprocal of the lysis time both in the presence and absence of the plasma or serum inhibitors. Inhibitory activity can be estimated, therefore, by the difference in lysis time between control clots containing a buffer or euglobulin component and plasma or serum containing clots both activated by a common concentration of urokinase selected from within the critical range. An experimental model for this purpose is described with an examination of the effects of each variable in this system and a reference curve in terms of a known inhibitor. In this study, it has been found that the effects of calcium are influenced by the plasminogen concentration and are biphasic in the presence of the serum inhibitors.