The direct clotiysis by urokinase (UK) may be due to exogenous clotlysis. On the other hand, the clot formed in the presence of UK may undergo endogenous clotlysis. To elucidate the optimal dosage of UK in the exogenous and endogenous clotlysis, the Chandler's loop method and thromboelastography (TEG) were used.
Fibrinogen, plasminogen, α2-macroglobulin, α1-antitrypsin, antithrombin III, α2-plasmin inhibitor, C1-inactivator, hematocrit and platelet count were measured. The correlation between these factors and clotlysis time on TEG were analysed.
In the loop method, UK agents from six companies (A-F) were used. previously formed Chandler's artificial clots were placed into loops containing 200, 120 and 60IU/ml of UK in saline solution, and these loops were rotated for 4-24 hours. Percentage reduction of clot weight was measured (Fig. 1).
In TEG, clotlysis time on TEG was measured using 5, 10, 20, 25, 30, 40, 50 and 100IU/ml of UK.
The artificial clots in 200IU/ml of UK solution showed mean clotlysis 55.8% in 4 hours by the Chandler's technique. By TEG, the clot formed in the presence of 10-20IU/ml of UK revealed clotlysis in 46-120min after clotting.
C1-INA and α2-PI showed correlation between clotlysis time on TEG (Fig. 2).