Objective   To investigate the effect of laminaria polysaccharide L₀₁ on activation of platelet and to study the mechanism of laminaria polysaccharide L ₀₁ inhibiting thrombus formation.

  Methods   The aged rats were divided into 4 groups: normal group, model group, laminaria polysaccharide L₀₁ high-dose and low-dose group.A rat model of vascular endothelial injury was established via injecting adrenaline.The activation of platelet adhesion was evaluated by comparing the difference of the platelet count before and after the blood filtration.The activation of platelet adhesion-aggregation on facet was observed by collodion-glass plate method.The plasma contents of von Willebrand Factor(vWF)and plateletαbranule membrane-glycoprotein 140(GMP-140)were measured by EL ISA.

  Results   Compared with model group, the percentage of platelet adhesion, the activation of platelet adhesion-aggregation on facet and the plasme level of vWF and GMP-140 were obviously decreased by both high dose group(100 mg/kg)and low group(10 mg/kg)of laminaria polysaccharide L₀₁ in aged rats of vascular endothelium in injury.

  Conclusion   The effect of inhibiting thrombus formation of laminaria polysaccharide L₀₁ associated with its effects of decreasing the plasma level of vWF and GMP-140 and inhibiting platelet adhesion and aggregation.