Experimental Study Of Nattokinase On Antithrombotic Mechanisms

Objective: To study the antithrombotic mechanisms of nattokinase.Methods: A model of acute blood stasis was established by means of giving rats an injection of adrenalin and making it swim in ice-cold water, the change of hemorheology was observed after the rats took nattokinase for 10 days; Rat platelet aggregation induced by ADP,thrombin and arachidonic acid, was measured by turbidimetric method at different time. The cytosolic free calcium concentration [Ca2+]i in rat platelets was measured with Fluo-3/ AM and the flowcytometer. The levels of TXB2, 6-Keto-PGF1α, NO and ET-1 in rat plasma and the levels of GMP-140 and vWF in human plasma were measured. Expression of t-PA, UK and PAI-1 mRNA in rat aorta tissue was examined by Real Time PCR.Results: Nattokinase could markedly decrease the whole blood viscosity of low, middle, and high shear rate, plasma viscosity, hematocrit, fibrinogen, erythrocyte aggregation index and electrophoresis index. Nattokinase could significantly inhibit platelet aggregation induced by ADP,thrombin and arachidonic acid , and the values of ED50 (median effective dose) were 1431.9 IU/kg for ADP, 1055.3 IU/kg for thrombin and 1390.8 IU/kg for arachidonic acid, respectively. Nattokinase could decrease the [Ca2+]i in rat platelets induced by thrombin. The levels of 6-Keto-PGF1αand NO were increased, while the levels of TXB2 , ET-1, and the ratios of TXB2/6-Keto-PGF1αand ET-1/NO were reduced. And the levels of GMP-140 and vWF in human plasma were also decreased. Nattokinase could significantly increase the mRNA expression of t-PA and UK, but not influence the mRNA expression of PAI-1.Conclusion: Nattokinase had the effect of anti- thrombosis, and its mechanisms might be associated with the improvement of hemorheology in rats of acute blood stasis, inhibition of platelet aggregation, including the reductions of [Ca²⁺]i in platelets, TXB2 and ET-1, increases of 6-Keto-PGF1αand NO, decreases of GMP-140 and vWF, and enhancement of fibrinolytic activity by promoting the gene expression of t-PA and UK.