Abstract: Objective To investigate the joint effects of flow shear stress and blood-activiating and stasis-dissolving drugs the fruit of Crataegus Pinnatifida Bge. Var. majar N.E. Br.(CP) and the root of Salviae Miltiorrhizae Bge(SM) on the expression of PAI-1, t-PA and ICAM-1 in endothelial cells damaged by OX-LDL and its possible antithrombotic mechanisms. Methods By using Bioflux 1000 microfluidic system, shear stresses of 0.1 Pa and 0.9 Pa were applied together with different doses of the fruit of CP and the root of SM treatment on human vascular endothelial cells (HUVECs) damaged by OX-LDL, then the cell supernatant was collected to detect concentration of PAI-1,t-PA and ICAM-1 by ELISA, the mRNA expressions of PAI-1,t-PA and ICAM-1 in cells were detected by RT-PCR. Results Compared with the model group, the contents of PAI-1 mRNA expressions were lower after treated with the fruit of CP and the root of SM and reduced the secretion of PAI-1 in cells supernatant. Physical shear stress of 0.9 Pa combined with the fruit of CP and the root of SM could significantly promote the endothelial secretion of t-PA and the contents of t-PA mRNA expressions were increased. The contents of ICAM-1 expressions were lower after treated with the fruit of CP and the root of SM in low shear stress condition. Conclusion The fruit of CP and the root of SM can inhibit thrombosis by inhibiting the expression of PAI-1 in endothelial cells. Physical shear stress and the fruit of CP and the root of SM can inhibit thrombosis by regulating the stability of the fibrinolytic system; low shear stress may influence the fruit of CP and the root of SM antithrombotic effect through downregulation of ICAM-1.

Key words: shear stress, the fruit of Crataegus Pinnatifida Bge. Var. majar N.E. Br. and the root of Salviae Miltiorrhizae Bge, endothelial cells, antithrombosis