不同形态低切应力对小鼠腹主动脉重构及内皮P选择素表达的影响

Effects of Variant Patterns of Fluid Shear Stress on Vascular Remodeling and Endothelial P-Selectin Expression of Mice Abdominal Aorta

目的制备小鼠腹主动脉狭窄的实验模型,探讨短期不同形态的低剪切应力对动脉重建及内皮P选择素表达的影响。方法 24只小鼠随机平均分为3个实验组(1h组、4h组、24h组)和1个正常对照组,实验组用动脉银夹建立腹主动脉局部狭窄模型,彩色多普勒超声检测狭窄近心端和远心端血流动力学参数,计算切应力值;血管标本行HE染色和内皮P选择素免疫组织化学染色,定量分析动脉病理形态学的改变和半定量分析内皮P选择素表达的强度。结果狭窄动脉近心端和远心端血流分别形成低切应力区和振荡性低切应力涡流区,并且在所有观察点狭窄动脉近心端和远心端血管发生不同程度的动脉重建与内皮P选择素表达,但近心端较远心端更明显(P<0.05)。结论血流动力学改变在较短的时间内可引起动脉重构及内皮P选择素的表达,而且不同形态低切应力导致的病变程度是不同的。

Aim To create an animal model for local change of shear stress to analyze the arterial wall response at different patterns of fluid shear stress. Methods 24 mice were equally randomized into three group （1 h group,4 h group and 24 h group） and one normal control group. A stenosis was set up with a cast attached to the wall of the abdominal aorta to change flow condition in test group. The parameters of hemodynamics and the internal diameter of blood vessel were measured by color Doppler flow imaging. The wall shear stress was calculated by Poiseiulle hydrodynamics formula （τm=η×4×Vm/D）. Pathological examination and immunohistochemistry were performed to observe the arterial morphological changes and the endothelial P-selectin expression. The intimal-media thickness and adventitia thickness of the aorta were measured and endothelial P-selectin expression intensity was analyzed qualitatively. Results Regions of low shear stress and oscillatory shear stress were created upstream and downstream of the cast respectively. Vascular remodeling and P-selectin expression in the upstream arterial wall were much more severe than those in the downstream in all observed time-points （P0.05）. Conclusion Vascular remodeling and endothelial P-selectin expression could happen in a relative short time when it exposed under low shear stress,meanwhile the variant patterns of fluid shear stress may play different roles in the pathological process of artery.