Contraluminal transport systems in the proximal renal tubule involved in secretion of organic anions.
Contraluminal transport systems in the proximal renal tubule involved in secretion of organic anions.
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近端肾小管的腔内转运系统参与有机阴离子的分泌。
DOI：
10.1152/ajprenal.1988.254.4.f453
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
G. Rumrich
中科院分区：
文献类型：
--
作者：
K. Ullrich;G. Rumrich
近端小管中有机阴离子的转运主要通过上皮细胞进行。该过程涉及通过专门的运输系统穿过管腔膜和对管腔膜的运动。虽然一些有机阴离子从管腔被吸收到细胞中，但它们也可以通过各种转运蛋白从间质室积聚在小管细胞中。阴离子对不同腔和对腔转运蛋白的相对亲和力与其共轭驱动力一起决定了净方向运动，即，有机阴离子的吸收或分泌。通过使用停流微灌流的方法，它已经有可能在大鼠的对腔阴离子转运的特点。已经确定了以下三种不同的系统：1）硫酸盐和草酸盐的交换系统; 2）Na+和二羧酸盐的共转运系统; 3）疏水阴离子和长链脂肪酸的交换系统（所谓的对氨基马尿酸转运系统）。通过使用各种不同的类似物，确定了这些不同系统的底物特异性。具有两个负离子电荷或具有一个负离子电荷和一个或多个负部分电荷的基底与所有三个系统相互作用，这取决于两个带电基团之间的距离。二羧酸盐体系优选多卤代底物。仅与对氨基马尿酸转运系统相互作用的底物具有疏水区域和一个负离子电荷或两个负部分电荷。
The transport of organic anions in the proximal tubule occurs primarily through the epithelial cells. This process involves movement across both the luminal and contraluminal membranes via specialized transport systems. Although some of the organic anions are taken up into the cell from the lumen, they can also be accumulated in tubule cells from the interstitial compartment by a variety of transporters. The relative affinities of anions for the different luminal and contraluminal transporters in concert with their conjugate driving forces determine the net directional movement, i.e., organic anion absorption or secretion. By use of the approach of stopped-flow microperfusion, it has been possible to characterize the contraluminal anion transporters in the rat. The following three different systems have been identified: 1) an exchange system for sulfate and oxalate; 2) a cotransport system for Na+ and dicarboxylates; and 3) an exchange system (the so-called p-aminohippuric acid transport system) for hydrophobic anions and long-chain fatty acids. By use of a wide variety of different analogues, the substrate specificities for these different systems were determined. Substrates with two negative ionic charges or with one negative ionic charge and one or more negative partial charges interact with all three systems, depending on the distance between the two charged groups. Polyhalogenated substrates are preferred by the dicarboxylate system. Those substrates which interact only with the p-aminohippurate transport system possess a hydrophobic area and one negative ionic charge or two negative partial charges.