Rubashkin A, Iserovich P, Hernández J A, Fischbarg J
Institute of Cytology, Russian Academy of Sciences, 194064, St. Petersburg, Russia.
J Membr Biol. 2005 Dec;208(3):251-63. doi: 10.1007/s00232-005-0831-y. Epub 2006 Apr 20.
The purpose of the present work is to investigate whether the idea of epithelial fluid transport based on electro-osmotic coupling at the level of the leaky tight junction (TJ) can be further supported by a plausible theoretical model. We develop a model for fluid transport across epithelial layers based on electro-osmotic coupling at leaky tight junctions (TJ) possessing protruding macromolecules and fixed electrical charges. The model embodies systems of electro-hydrodynamic equations for the intercellular pathway, namely the Brinkman and the Poisson-Boltzmann differential equations applied to the TJ. We obtain analytical solutions for a system of these two equations, and are able to derive expressions for the fluid velocity profile and the electrostatic potential. We illustrate the model by employing geometrical parameters and experimental data from the corneal endothelium, for which we have previously reported evidence for a central role for electro-osmosis in translayer fluid transport. Our results suggest that electro-osmotic coupling at the TJ can account for fluid transport by the corneal endothelium. We conclude that electro-osmotic coupling at the tight junctions could represent one of the basic mechanisms driving fluid transport across some leaky epithelia, a process that remains unexplained.
本研究的目的是探讨基于紧密连接（TJ）水平上的电渗耦合的上皮液体运输概念是否能得到一个合理的理论模型的进一步支持。我们基于具有突出大分子和固定电荷的紧密连接（TJ）处的电渗耦合，开发了一个跨上皮层液体运输的模型。该模型包含细胞间途径的电流体动力学方程组，即应用于紧密连接（TJ）的布林克曼方程和泊松 - 玻尔兹曼微分方程。我们获得了这两个方程系统的解析解，并能够推导流体速度分布和静电势的表达式。我们通过使用来自角膜内皮的几何参数和实验数据来说明该模型，我们之前已经报道了电渗在跨层液体运输中起核心作用的证据。我们的结果表明，紧密连接（TJ）处的电渗耦合可以解释角膜内皮的液体运输。我们得出结论，紧密连接处的电渗耦合可能代表驱动液体跨一些紧密上皮运输的基本机制之一，而这一过程仍未得到解释。
