Influence of thrombin inhibitors on the thrombin-induced activation of human blood platelets

The influence of thrombin inhibitors, which differ both in their chemical structure and type of inhibition, on the thrombin-platelet reaction was studied. The inhibitory effects of the competitive inhibitors tested on the thrombin-induced platelet reaction correlated well with their effects on the thrombin-catalyzed fibrinogen conversion and on the thrombin-catalyzed hydrolysis of synthetic substrates. Heparin and antithrombin III inhibited the thrombin-induced platelet reaction. However, heparin did not potentiate the inhibition by antithrombin III of the thrombin-platelet reaction.