t-PA has been well known to show thrombolytic activity mediated through the activation of plasminogen. The activation is markedly stimulated in the presence of fibrin. Although t-PA tightly binds to fibrin, it has not been clarified how long the activity of the binding t-PA to thrombus is sustained in the physiological condition. Therefore, we examined the correlation between the binding amount of t-PA to thrombus and the duration of the thrombolytic activity induced by only the binding t-PA in vivo.After human plasma clots were immersed in human plasma containing various concentration of t-PA or LUK for 1min, the clots were washed with saline and immersed in the plasma without t-PA or LUK. The clots pretreated with t-PA were lysed for 3 hours continuously and the clot lysis is clearly correlated with the binding amount of t-PA to clot.On the other hand, the clots pretreated with LUK lacking in fibrin affinity were never lysed significantly.When the rabbit with pulmonary embolism was injected with t-PA (300,000 IU/kg i.v.), the circulating t-PA was quickly disappeared and was detected only slight(17±10 IU/ml) after 30min. However, the degree of thrombolysis was increased for 120min after the injection of t-PA(17±3.5%at 30min; 31±3.2% at 120min).These results indicate that the binding t-PA not only to plasma clots but also to thrombi is active and the thrombi bound with t-PA continue lysing at least for several hours even in the absence of free form of t-PA in plasma.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.