Reperfusion After Venous Occlusion Caused Transient Increase in Plasminogen Activator Inhibitor-1 in Systemic Circulation

From the point of local regulation, we investigated fibrinolytic activity both in local and systemic circulations, using a venous occlusion test as a stimulus of tissue plasmin ogen activator (t-PA) release in human volunteers. Blood samples were taken before, during, and after venous occlusion from the occluded arm as trapped blood and the unoccluded arm as blood of systemic circulation. In these samples, fibri nolytic activity by euglobulin-clot lysis time and related factors in t-PA and plasminogen activator inhibitor-1 (PAI-1) were measured. Venous occlusion increased fibrinolytic activity ac companied by an increase in t-PA without an increase in PAI-1 on the occluded arm. The fibrinolytic activity on the unoc cluded arm did not change. Five minutes after reperfusion, however, a transient increase in PAI-1 and no change of fibri nolytic activity were observed in the unoccluded arm. Transient increase of PAI-1 after reperfusion was also observed in the occluded arm. These results suggested that increased t-PA by venous occlusion was neutralized by released PAI-1 after reperfusion. Key Words: Tissue-plasminogen activator— Euglobulin-clot lysis time—Fibrinolysis.