Comparison of two experimental thrombosis models in rats effects of four glycosaminoglycans.

Two experimental thrombosis models in rats have been compared with regard to the composition of the formed thrombi and the effects of various treatments on thrombus formation. In the first model thrombosis is induced in the vena cava by a combination of venous stasis and hypercoagulability; these thrombi consist merely of red cells and fibrin with only a few platelets. In the second model thrombosis is induced in an arterio-venous shunt in which the formed thrombi consist of red cells, fibrin and a large amount of platelet aggregates adhering to the foreign material. Antiplatelet serum and acetylsalicylic acid, which reduce blood platelet activity, inhibited thrombus formation only in the arteriovenous shunt model. Dicumoxane, an oral anticoagulant, was active in both models. The glycosaminoglycans heparin, Org 10172, Fragmin and the pentasaccharide, representing the AT-III binding sequence of heparin, were active in both models. However, there were qualitative and quantitative differences between the effects of the glycosaminoglycans suggesting differences in their modes of action.