A TECHNIQUE TO INVESTIGATE MICROVASCULAR MURAL THROMBUS FORMATION IN ARTERIES AND VEINS .2. EFFECTS OF ASPIRIN, HEPARIN, R-HIRUDIN, AND G-4120

After a standardized trauma to carotid arteries or femoral veins of ha msters, the antithrombotic effects of two antiplatelet agents (aspirin and the glycoprotein IIb/IIIa antagonist G4120) and two anticoagulant s (heparin and the direct thrombin inhibitor r-hirudin) were studied i n vivo, The thrombus area volume was assessed by image analysis of the transilluminated experimental vessels, Heparin, r-hirudin, and G-4120 demonstrated a dose-dependent complete inhibition of arterial and ven ous thrombosis, In contrast, the antithrombotic effect of aspirin was only partial in both vessel types. A significant correlation between a ctivated partial thromboplastin time (aPTT) at the end of the experime nts and the antithrombotic effect was observed with the anticoagulant agents, However, only r-hirudin inhibited thrombus formation at a ther apeutical prolongation of aPTT, while heparin required supra-therapeut ical amounts to achieve the same inhibition, The data confirm that the inhibition of aspirin, heparin, r-hirudin, and G-4120 on the formatio n of platelet-rich thrombi is independent of the blood flow rate.