自发性高血压大鼠颈总动脉的平均壁面切应力和周向应力

Mean wall shear stress and circumferential stress in common carotid artery in spontaneously hypertensive rats

目的确定自发性高血压大鼠(SHR)颈总动脉的平均壁面切应力(WSS)和周向应力(CS),并与同龄正常血压大鼠(WKY)相对比,观察SHR和WKY大鼠颈总动脉平均WSS和CS的特征。方法选取12周龄SHR作为动物模型,同龄WKY为对照组;通过在体测定颈总动脉的平均血流量与平均血压,离体测量颈总动脉的无载荷状态形态学数据,以及在体轴向伸长比条件下颈总动脉段的压力(p)-容积(V)关系,确定颈总动脉平均WSS和CS;同时比较SHR和WKY颈总动脉的平均血压和血流量、无载荷和载荷状态几何尺寸以及平均WSS和CS的特征。结果与正常血压的WKY组相比,SHR组颈总动脉血压明显增高、流量明显降低;无载荷和载荷状态下SHR组动脉的内外半径均增大,载荷状态下SHR组动脉壁厚减小;SHR颈总动脉平均WSS明显降低,而CS明显增高。结论高血压和低流量引起了SHR颈总动脉重建;低WSS和高CS是SHR颈总动脉血液动力学参数的重要特征;WSS和CS的协同作用可能是反映动脉重建的敏感指标之一。

Objective The mean wall shear stress （WSS） and circumferential stress （CS） in common carotid artery （CCA） for spontaneously hypertensive rats （SHRs） were investigated by comparing with those in wistar Kyoto rats （WKYs） to determine the characteristics of WSS and CS in CCA in SHRs. Methods Five twelve-week-old SHRs were chosen as an experimental group, with 5 WKYs of the same age as control. The blood pressure and flow rate in CCA were simultaneously measured in vivo, the morphological indices of CCA at no-load state, and the pressure （p）-volume （V） relationship of CCA in vivo under longitudinal stretch ratios were measured in vitro in SHRs and WKYs. Using these data, the mean WSS and CS in CCA in SHRs and WKYs were calculated. The obtained blood pressure and blood flow, the geometrical sizes at no-load and load states, and the mean WSS and CS were compared between SHRs and WKYs. Results The blood pressure in SHRs was significantly higher than that in WKYs, and the flow rate in SHRs was obvious lower than that in WKYs; Both the inner and outer radius at no-load/load state in SHRs were higher than those in WKYs, while the vascular wall thickness in SHRs was smaller than that in WKYs. The mean WSS in SHRs was significantly lower than that in WKYs while the CS in SHRs was significantly higher than that in WKYs. Conclusion High blood pressure and low flow rate may induce the vascular remodeling in CCA. Low WSS together with high CS is important hemodynamic characteristic of CCA. The synergistic action of WSS and CS might be one of the most sensitive indices reflecting arterial remodeling.