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Coagulation-associated enhancement of fibrinolytic activity via a neutralization of PAI-1 activity

T Urano1, H Ihara, Y Suzuki

  • 1Department of Physiology, Hamamatsu University School of Medicine, Japan. uranot@hama-med.ac.jp

Seminars in Thrombosis and Hemostasis
|May 11, 2000
PubMed

Total fibrinolytic activity in the vasculature is finely tuned by the balance between tissue plasminogen activator and plasminogen activator inhibitor type 1 (PAI-1). Although PAI-1 targets plasminogen activators, it also reacts with other serine proteases such as thrombin and factor Xa. The latter was shown to interact with PAI-1 only when a physiological concentration of calcium ions (Ca++) is present. Through such interaction, thrombin and Ca++-bound factor Xa shortened fibrin clot lysis times in a purified system by neutralizing PAI-1 activity. Both unfractionated heparin and vitronectin were shown to enhance the clot lysis further. Together with the cleavage and inactivation of PAI-1 by human neutrophil elastase, which was reported previously from our laboratory, such neutralization of PAI-1 activity by these serine proteases was shown to be strongly involved in the coagulation-associated enhancement of fibrinolytic activity.

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