Distributions of wall shear stress in venular convergences of mouse cremaster muscle
Distributions of wall shear stress in venular convergences of mouse cremaster muscle
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DOI：
10.1038/sj.mn.7800182
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发表时间：
2003-04-01
期刊：
影响因子：
2.4
通讯作者：
Sarelius, IH
中科院分区：
文献类型：
--
作者：
Kim, MB;Sarelius, IH
目的：壁面切应力调节多种血管功能，可独立受血液粘度和壁面切变率变化的影响。因此，研究毛细血管后小静脉汇聚流区的管壁切应力分布，以确定切变率和粘度对管壁切变率的相对贡献，并确定静脉分支是否直接影响局部切变环境。方法：根据荧光红细胞(RBC)流量，评估血液粘度作为血管直径和红细胞压积的函数。壁面剪切率直接从使用荧光BBC跟踪获得的速度分布测量，或在假设Poiseuille流动条件下估计。结果：壁面剪应力的测量结果与汇聚区的位置无显著差异(p<；0.9)。对于局部红细胞压积(2.9+/-0.1cp；变异系数[CV]：12%)或全身性红细胞压积(3.4+/-0.1cpise[cp]；变异系数：14%)而言，粘度测量的变化很小。室壁剪切率的直接测量结果(61.2s+/-8.7s；CV：92%)和Poisettille血流的估计值(122.7+/-15.7s S；CV：83%)均显示出更大的变异性。结论：与小动脉分叉相反，室壁切应力的变化与微静脉汇聚的部位无关。此外，壁面剪切率的变化比粘度大得多，因此，这主要是毛细血管后小静脉壁面切应力变化的原因。
Objective: Wall shear stress regulates a variety of vascular functions and can be affected by variations in blood viscosity and wall shear rate independently. Therefore, the distribution of wall shear stress was characterized in converging flow regions of postcapillary venules to identify the relative contributions of shear rate and viscosity to wall shear rate and to determine whether venular branching directly affects the local shear environment.Methods: Blood viscosity was evaluated as a function of vessel diameter and hematocrit, determined from fluorescent red blood cell (RBC) flux. Wall shear rate was measured directly from velocity profiles acquired using fluorescent BBC tracking or was estimated assuming Poiseuille flow conditions. Wall shear stress was calculated for measurements made across regions of converging flow.Results: Measurements of wall shear stress showed no significant variation with location across the convergence (p < 0.9). Measures of viscosity showed little variation, for local measures of hematocrit (2.9 +/- 0.1 cp; coefficient of variation [CV]: 12%) or systemic hematocrit (3.4 +/- 0.1 centipoise [cp]; CV: 14%). Measures of wall shear rate showed greater variability for both direct measurements (61.2 +/- 8.7s; CV: 92%) and estimates assuming Poisettille flow (122.7 +/- 15.7 s; CV: 83%).Conclusions: Variations in wall shear stress are independent of location through a venular convergence in contrast to arteriolar bifurcations. In addition, wall shear rate is significantly more variable than viscosity and, therefore, primarily accountable for wall shear stress variations in postcapillary venules.