Relationship of urokinase type plasminogen activator, plasminogen activator inhibitor type 1 and activated protein C in fibrinolysis of human placenta.

Suppression of the fibrinolytic activity plays an important role in the prevention of hemorrhage during pregnancy and labor. A hypofibrinolytic and hypercoagulable state may be established in the placenta during pregnancy. However, little infraction is present in the normal placenta. This evidence shows that placenta maintains the fibrinolytic activity in spite of hypercoagulable state. As there is a high amount of APC in the placenta, APC is thought to be involved in fibrinolysis of placenta. Thus, we studied the role of APC on fibrinolysis in placenta. (1) uPA activity of cell membrane reappears after incubation with uPA/PAI-1 complex and a large amount of APC by flow cytometry, (2) APC was made PAI-1/APC complex after incubation of uPA/PAI-1 complex with APC. Our results suggest that APC is the important substance for fibrinolysis in the placenta by decreasing of PAI activity.