Pharmacodynamic Studies On Antithrombotic Effects Of RLj-RGD3 In Animals

Objective: To investigate the anti-thrombotic effects and its mechanism of rLj-RGD3 in order to provide preclinical pharmacological basis for its development as a new drug.Methods: The anti-artery thrombosis effect of rLj-RGD3 was examined in an electrically induced rat carotid thrombosis model by registering the occlusion time ( OT ). The stasis-induced inferior vena cava thrombosis model was made according to Rayers'method. The anti-venous thrombosis effect of rLj-RGD3 was evaluated in terms of thrombus formation rate and the decrease in thrombus dry weight. Mice were challenged by iv 2500 IU·kg^-1 thrombin to induce mouse pulmonary thromboembolism. The mortality and protective percentage were recorded to evaluate the anti-pulmonary thromboembolism effect of rLj-RGD3. TT, PT and APTT were determined to investigate the influence of rLj-RGD3 on coagulation system. Blood viscosity and plasma viscosity were measured to study the effect of rLj-RGD3 on hemorrheology. 5 min maximum platelet aggregation rate induced by ADP was determined to examine the anti- platelet aggregation effect of rLj-RGD3. The tail bleeding time ( BT ) was recored to compare hemorrhage tendency between rLj-RGD3 and heparin at the same protective effect dose against thrombin-induced mouse pulmonary thromboembolism death.Results: rLj-RGD3 dose-dependently prolonged OT ( 12.5¹00.0μg·kg^-1 ), decreased thrombus formation rate and thrombus dry weight ( 3.13²5.00μg·kg^-1 ), increased protective percentage against thrombin-induced mouse pulmonary thromboembolism death ( 0.13².00 mg·kg^-1 ). rLj-RGD3 inhibited 5 min maximum platelet aggregation rate induced by ADP ex vivo ( 12.5¹00.0μg·kg^-1 ) and in vitro ( 62.50¹17.65μg·mL^-1 ), dose-dependently. rLj-RGD3 had no influence on TT, PT, APTT, blood viscosity and plasma viscosity. rLj-RGD3 ( 0.300 mg·kg^-1 ) and heparin ( 200 IU·kg^-1 ), at equal effective doses, increased BT by 323.8 % and 78.1 %, respectively. rLj-RGD3-caused prolongation of BT was 24.1 % as much as that of heparin.Conclusion: rLj-RGD3 has powerful anti-artery thrombosis effect, anti-venous thrombosis effect and anti-pulmonary thromboembolism effect at low dose. The main mechanism of its anti-thrombotic effect is to inhibit platelet aggregation. But it has no effect on coagulation system and hemorrheology. The hemorrhage tendency of rLj-RGD3 is less than that of heparin at equal effective doses against thrombin-induced mouse pulmonary thromboembolism death.