The effect of thrombin inhibition in a rat arterial thrombosis model

The effect of heparin and the synthetic irreversible antithrombin D-phenylalanyl-L-prolyl-L-arginyl chloromethyl ketone (FPRCH2Cl) was studied on FeCl3-induced thrombotic occlusion of rat carotid arteries. Thrombocytopenia prevented occlusion in five of 7 rats for the 60 min observation period after FeCl3 injury demonstrating platelet dependence in this model of thrombosis. Intravenous injection of heparin (250 units/kg) followed by continuous infusion (250 units/kg/hr) failed to prevent occlusion in four of 6 rats whereas intravenous FPRCH2Cl infusion prevented occlusion at a dose of 200 nmol/kg/min during infusion in 6/6 rats. These findings indicate that thrombin plays a principle role in the platelet-dependent process of arterial thrombosis in FeCl3-damaged rat carotid arteries. Neutralization of the thrombogenic stimulus in this model by the thrombin inhibitor FPRCH2Cl suggests selective thrombin inhibition may be useful in the treatment of arterial thrombosis.