Fibrinolysis in the rat after short-term aspirin therapy.

Fibrinolytic parameters were compared in blood taken from rats treated with aspirin (10 and 40 mg/kg) or saline solution. Plasma euglobulin fractions prepared from animals treated with the higher dose of aspirin caused increased zones of lysis on plasminogen-rich fibrin plates. Even greater lytic activity was detected in blood from all aspirin-treated rats when euglobulin fractions were augmented with sodium flufenamate and dextran sulfate. The inhibitor index was significantly reduced when calculated for rats treated with the larger dose of drug. Dilute blood clot lysis times for this group were consistently prolonged, most likely reflecting impaired platelet function. Platelet counts, hematocrits, and bleeding times did not differ from controls. Prothrombin times, activated partial thromboplastin times, and plasma clot times were all prolonged, reflecting the sensitivity of the vitamin K-dependent factors to aspirin.