Nonlinear flow affects hydrodynamic forces and neutrophil adhesion rates in cone-plate viscometers.
Nonlinear flow affects hydrodynamic forces and neutrophil adhesion rates in cone-plate viscometers.
复制标题
DOI：
10.1016/s0006-3495(01)76233-9
复制
发表时间：
2001-06
影响因子：
3.4
通讯作者：
H. Shankaran;S. Neelamegham
中科院分区：
文献类型：
--
作者：
H. Shankaran;S. Neelamegham
本文从理论和实验两方面分析了锥板粘度计中非线性流动的影响。分析预测，粘度计中的流动是雷诺数和锥角这两个参数的函数。非线性流动在高剪切速率下发生，并导致粘度计内的壁面剪切应力、碰撞频率、颗粒间力和附着时间的空间变化。我们研究了这些功能对细胞粘附动力学的影响。根据最近的数据（泰勒，A。D、S. Neelamegham，J. D. Hellums，et al. 1996. Biophys. J. 71：3488-3500），我们将嗜中性粒细胞同型聚集建模为在低剪切下整合素受限且在高剪切下选择素受限的过程。我们的计算表明，选择素和整合素的结合率约为10 - 2-10 - 4/s。他们还表明，二次流导致粘度计中的粘附效率的位置变化，并且整体效率不仅取决于剪切速率，而且还取决于样品体积和锥角。用分离的中性粒细胞进行的实验证实了这些预测。在这些实验中，通过以1500/s的速度将样品体积从100 μl增加到1000μl来增强二次流，对于2°锥体，导致粘附效率下降高达45%。我们的研究结果表明，二次流可能会显着影响细胞聚集，血小板活化，和内皮细胞mechanotransduction测量中的粘度计在典型的生物学研究中应用的条件范围内。
We present a theoretical and experimental analysis of the effects of nonlinear flow in a cone–plate viscometer. The analysis predicts that flow in the viscometer is a function of two parameters, the Reynolds number and the cone angle. Nonlinear flow occurs at high shear rates and causes spatial variations in wall shear stress, collision frequency, interparticle forces and attachment times within the viscometer. We examined the effect of these features on cellular adhesion kinetics. Based on recent data (Taylor, A. D., S. Neelamegham, J. D. Hellums, et al. 1996.Biophys. J.71:3488–3500), we modeled neutrophil homotypic aggregation as a process that is integrin-limited at low shear and selectin-limited at high shear. Our calculations suggest that selectin and integrin on-rates lie in the order of 10−2–10−4/s. They also indicate that secondary flow causes positional variations in adhesion efficiency in the viscometer, and that the overall efficiency is dependent not only on the shear rate, but also the sample volume and the cone angle. Experiments performed with isolated neutrophils confirmed these predictions. In these experiments, enhancing secondary flow by increasing the sample volume from 100 to 1000μl at 1500/s for a 2° cone caused up to an ∼45% drop in adhesion efficiency. Our results suggest that secondary flow may significantly influence cellular aggregation, platelet activation, and endothelial cell mechanotransduction measurements made in the viscometer over the range of conditions applied in typical biological studies.