Abstract: Objective To study the joint effects of shear stress and pressure on secretion and expression of PAI-1,t-PA, vWF in endothelium of isolated rabbit vessel. Methods Ex vivo arterial perfusion system was used to establish the rabbit artery perfusion model under different flow conditions of shear stress (2~22 dyn·cm^-2) and different pressure(9.0~48.4 mmHg). The perfusate was collected to determine the level of vWF, PAI-1 and t-PA by using radioimmunoassay. And the expression level of vWF mRNA,PAI-1 mRNA and t-PA mRNA was measured by real-time PCR method. Results The low shear stress combined with the low normal pressure, the medium shear stress combined the medium normal pressure and the higher shear stress with the higher normal pressure decreased the level of PAI-1 in perfusate, and meanwhile up-regulated the gene expression of PAI-1. The medium shear stress combined the medium normal pressure increased the level of t-PA in perfusate and up-regulated expression of t-PA. The high shear stress combined with the high normal pressure decreased the level of vWF. Conclusion In isolated blood vessel model loaded by shear stress, shear stress and pressure could exert a joint effects on endothelial functions, which may be related with gene expression of vWF, PAI^-1 and t-PA, which indicated that the physical and pathological importance deserves further investigation on the quantitative relationship between biological effects and shear stress.

Key words: shear stress, pressure, endothelium, gene expression, rabbit