Modified clotting properties of fibrinogen in the presence of acetylsalicylic acid in a purified system.

To assess how treatment with acetylsalicylic acid (ASA) alters the fibrin network structure, clotting was initiated in purified fibrinogen incubated with ASA by adding thrombin. Clotting time and maximum absorbance of the fibrin aggregation curve were used to demonstrate the potential of fibrin generation. The results showed that the clotting properties of fibrinogen decreased and that the affinity of plasminogen to fibrin or thrombin inhibition by antithrombin increased if plasminogen or antithrombin, respectively, were present in the reaction system. The effect of ASA varied in a dose dependent manner. It was concluded that ASA may directly or indirectly confer positive or negative effects on the stability of the fibrin clot and that the balance between these effects may be regulated by the ASA dose.