Convective paracellular solute flux. A source of ion-ion interaction in the epithelial transport equations.
Convective paracellular solute flux. A source of ion-ion interaction in the epithelial transport equations.
复制标题
对流细胞旁溶质通量。
DOI：
10.1085/jgp.89.3.501
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Weinstein,AM
中科院分区：
文献类型：
--
作者：
Weinstein,AM
电解质模型的上皮细胞（一个细胞和一个紧密连接的平行，都在一个横向间隙基底膜串联）进行了分析，使用非平衡态热力学的形式主义。结果表明，如果平行结构是异质多孔的（即，两种离子种类的反射系数在组分之间不同），则交叉项将出现在上皮的总传输方程中。形式上，该交叉项表示离子-离子相互作用。相对于大鼠近端小管，数据表明上皮离子反射系数小于1，再加上假设没有跨细胞溶剂阻力，意味着对流细胞旁溶质通量的存在。这意味着必须使用适用于异质多孔结构的模型来表示小管，并且特别地，还必须在渗透性测定中评估离子-离子相互作用的交叉项。一系列的计算，允许估计的钠-氯相互作用的大鼠近端小管从现有的实验数据。小管异孔性的一个结果是，在驱动重吸收离子通量方面，电势可能比等效浓度梯度有效得多。
An electrolyte model of an epithelium (a cell and a tight junction in parallel, both in series with a lateral interspace basement membrane) is analyzed using the formalism of nonequilibrium thermodynamics. It is shown that if the parallel structures are heteroporous (i.e., reflection coefficients for two ion species differ between the components), then a cross-term will appear in the overall transport equations of the epithelium. Formally, this cross-term represents an ion-ion interaction. With respect to the rat proximal tubule, data indicating epithelial ionic reflection coefficients less than unity, together with the assumption of no transcellular solvent drag, imply the presence of convective paracellular solute flux. This means that a model applicable to a heteroporous structure must be used to represent the tubule, and, in particular, the cross-terms for ion-ion interaction must also be evaluated in permeability determinations. A series of calculations is presented that permits the estimation of the Na-Cl interaction for rat proximal tubule from available experimental data. One consequence of tubule heteroporosity is that an electrical potential may be substantially less effective than an equivalent concentration gradient in driving reabsorptive ion fluxes.