Summary
Thrombin activity was assayed on the aortic surface of rabbits after soft tissue trauma
or endothelial injury caused by a balloon catheter. The animals were sacrificed by
exsanguination 20 minutes or 3 hours after either type of trauma. Thrombin amidolytic
activity on the luminal surface of the aorta was measured by exposing it to a synthetic
chromogenic substrate.
Thrombin activity appeared on the aortic endothelium 3 hours but not 20 minutes after
soft tissue trauma. Heparin prevented the appearance of thrombin activity completely
only if given just before the trauma. After endothelial injury, thrombin activity
appeared on the vascular surface after 3 hours but not after 20 minutes.
Thrombin activity appearing on the endothelium after soft tissue trauma may explain
posttraumatic thrombotic events. The thrombin activity could, however, also be directed
towards activation of protein C in which case an anticoagulant effect is obtained.
Thrombin appearing after endothelial injury may enhance reactivity on the damaged
vessel wall.
Key words
Endothelium - Subendothelium - Trauma - Thrombin