Mechanism of osmotic flow in a periodic fiber array.
Mechanism of osmotic flow in a periodic fiber array.
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DOI：
10.1152/ajpheart.00695.2005
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发表时间：
2006-02
期刊：
影响因子：
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通讯作者：
Xiaobing Zhang;F. Curry;S. Weinbaum
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文献类型：
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作者：
Xiaobing Zhang;F. Curry;S. Weinbaum
Anderson和Malone （Biophys J 14: 957-982, 1974）对具有长圆柱孔的膜的渗透流进行了经典分析，将其扩展到纤维基质层，其中纤维本身就是其边界。众所周知的反射系数sigma0 = (1 - phi)2的等效结果，其中phi是分配系数，是为六边形有序核心蛋白质的周期性纤维阵列导出的。描述每根纤维周围溶质分布的势能函数的边值问题通过定义一个等效的流体环空来解决，其中的压力和渗透力是确定的。该模型对水在毛细血管壁上的渗透流动特别感兴趣，最近的实验研究表明，内皮糖萼是一种准周期纤维阵列，可作为血浆蛋白的主要分子筛。反射系数的计算结果以两个无量纲数alpha = a/R和beta = b/R表示，其中a和b分别为溶质半径和纤维半径，R为流体环空的外半径。一般来说，由于产生渗透力的边界的形状有很大的不同，结果与圆形孔的经典表达式有很大的不同。然而，正如在圆孔理论中，人们发现渗透和过滤的反射系数是相同的。
The classic analysis by Anderson and Malone (Biophys J 14: 957-982, 1974) of the osmotic flow across membranes with long circular cylindrical pores is extended to a fiber matrix layer wherein the confining boundaries are the fibers themselves. The equivalent of the well-known result for the reflection coefficient sigma0 = (1 - phi)2, where phi is the partition coefficient, is derived for a periodic fiber array of hexagonally ordered core proteins. The boundary value problem for the potential energy function describing the solute distribution surrounding each fiber is solved by defining an equivalent fluid annulus in which the pressures and osmotic forces are determined. This model is of special interest in the osmotic flow of water across a capillary wall, where recent experimental studies suggest that the endothelial glycocalyx is a quasiperiodic fiber array that serves as the primary molecular sieve for plasma proteins. Results for the reflection coefficient are presented in terms of two dimensionless numbers, alpha = a/R and beta = b/R, where a and b are the solute and fiber radii, respectively, and R is the outer radius of the fluid annulus. In general, the results differ substantially from the classic expression for a circular pore because of the large difference in the shape of the boundary along which the osmotic force is generated. However, as in circular pore theory, one finds that the reflection coefficients for osmosis and filtration are the same.