A model of a radially expanding and contracting lymphangion.
A model of a radially expanding and contracting lymphangion.
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DOI：
10.1016/j.jbiomech.2011.02.018
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发表时间：
2011-04-07
影响因子：
2.4
通讯作者：
Moore, James E., Jr.
中科院分区：
文献类型：
--
作者：
Rahbar, Elaheh;Moore, James E., Jr.
淋巴系统是一个广泛的血管网络，具有瓣膜和收缩壁，将间质液和血浆蛋白泵回主循环。免疫功能也依赖于淋巴系统运输白细胞的能力。不能排出和泵送这些多余的液体会导致水肿，其特征是液体潴留和四肢肿胀。因此，了解淋巴管的流体输送和泵送机制是很重要的。遗憾的是，这方面的研究很少，大多数研究都假设了泊泽维尔流动条件。体内观察显示，这些血管收缩强烈，直径变化的数量级是直径本身的一个周期，通常持续2-3秒。收缩血管的径向速度与轴向流体速度相同，这表明用泊泽维尔模型来模拟这些血管中的流动是不合适的。在本文中，我们描述了一个径向扩张和收缩的淋巴管模型，并研究了假设泊泽维尔流来估计壁剪切应力的有效性，这可能对淋巴内皮细胞的机械转导很重要。三种不同的墙体运动；研究了稳定和非稳定抛物线入口速度下的周期正弦、倾斜正弦和生理性壁面运动。尽管壁面运动导致了很高的径向速度，但壁面剪切应力值在准静态Poiseuille值的4%以内。因此，泊泽维尔流对于大多数淋巴管收缩周期的壁剪应力估计是有效的。
The lymphatic system is an extensive vascular network featuring valves and contractile walls that pump interstitial fluid and plasma proteins back to the main circulation. Immune function also relies on the lymphatic system’s ability to transport white blood cells. Failure to drain and pump this excess fluid results in edema characterized by fluid retention and swelling of limbs. It is, therefore, important to understand the mechanisms of fluid transport and pumping of lymphatic vessels. Unfortunately, there are very few studies in this area, most of which assume Poiseuille flow conditions. In vivo observations reveal that these vessels contract strongly, with diameter changes of the order of magnitude of the diameter itself over a cycle that lasts typically 2–3 seconds. The radial velocity of the contracting vessel is on the order of the axial fluid velocity, suggesting that modeling flow in these vessels with a Poiseuille model is inappropriate. In this paper, we describe a model of a radially expanding and contracting lymphatic vessel and investigate the validity of assuming Poiseuille flow to estimate wall shear stress, which is presumably important for lymphatic endothelial cell mechanotransduction. Three different wall motions; periodic sinusoidal, skewed sinusoidal and physiologic wall motions, were investigated with steady and unsteady parabolic inlet velocities. Despite high radial velocities resulting from the wall motion, wall shear stress values were within 4% of quasi-static Poiseuille values. Therefore, Poiseuille flow is valid for the estimation of wall shear stress for the majority of the lymphangion contractile cycle.
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