Na/H antiporter mRNA expression in single nephron segments of rat kidney cortex.
Na/H antiporter mRNA expression in single nephron segments of rat kidney cortex.
复制标题
大鼠肾皮质单个肾单位片段中 Na/H 逆向转运蛋白 mRNA 的表达。
DOI：
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发表时间：
1991
影响因子：
15.9
通讯作者：
M. Solioz
中科院分区：
文献类型：
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作者：
R. Krapf;M. Solioz
肾皮质小管由极化的上皮细胞组成，其中Na/H反向转运活性已在顶膜和/或基底外侧膜上得到证实。顶端Na/H逆向转运活性在跨细胞重吸收HCO 3-中起重要作用，而基底外侧Na/H逆向转运活性可能参与跨细胞HCO 3-分泌以及细胞体积和pH控制。为了确定这种异质性的定位和功能是否是由于存在一个以上的Na/H逆向转运蛋白，我们研究了Na/H逆向转运蛋白mRNA的组织分布，通过使用逆转录（RT）和聚合酶链反应（PCR）在分离的肾单位段从大鼠肾皮质。使用的引物针对大鼠肾皮质Na/H逆向转运蛋白cDNA，其与人生长因子活化的Na/H逆向转运蛋白同源。进行β-肌动蛋白mRNA的RT/PCR作为阳性对照。Na/H逆向转运蛋白mRNA在近端小管中的表达在浅表和最中皮质肾单位的S1和S2段中未检测到，其仅表现出腔Na/H逆向转运活性。它表达于延髓肾单位的S1和S2节段，也具有基底外侧Na/H反向转运活性。β-肌动蛋白mRNA在近端小管的所有节段中均匀表达。Na/H反向转运蛋白mRNA也在皮质粗升支和皮质集合管、具有基底外侧Na/H反向转运活性的节段以及肾小球中表达。总之，肾皮质中至少存在两种不同的Na/H反向转运蛋白，即，近端小管基底外侧Na/H反向转运体活性的功能定位和mRNA表达之间的密切相关性表明，大鼠肾Na/H反向转运体DNA同源的人生长因子活化的Na/H反向转运体编码的基底外侧交换。在少数皮质中近端小管中观察到的表达可能反映了这些肾单位片段的一定异质性。
Renal cortical tubules consist of polarized epithelial cells where Na/H antiport activity has been demonstrated on the apical and/or basolateral membrane. Apical Na/H antiport activity plays an important role in transcellular bicarbonate (HCO3-) reabsorption, whereas basolateral Na/H antiport activity could be involved in transcellular HCO3- secretion as well as cell volume and pH control. To determine whether this heterogeneity in both localization and function is due to the existence of more than one Na/H antiporter, we studied the tissue distribution of Na/H antiporter mRNA by use of reverse transcription (RT) and polymerase chain reaction (PCR) in isolated nephron segments from rat renal cortex. The primers used were directed against the rat renal cortical Na/H antiporter cDNA which is homologous to the human growth factor-activatable Na/H antiporter. RT/PCR of beta-actin mRNA were performed as positive controls. Na/H antiporter mRNA expression in the proximal tubule was not detectable in S1 and S2 segments from superficial and most midcortical nephrons, which exhibit exclusively luminal Na/H antiport activity. It was expressed in S1 and S2 segments from juxtamedullary nephrons which have also basolateral Na/H antiport activity. Beta-actin mRNA was expressed uniformly in all segments of the proximal tubule. Na/H antiporter mRNA was also expressed in cortical thick ascending limb and cortical collecting duct, segments with basolateral Na/H antiport activity as well as in the glomeruli. In conclusion, at least two different Na/H antiporters exist in the renal cortex, i.e., the proximal tubule. The close correlation between functional localization of basolateral Na/H antiport activity and mRNA expression suggests that the rat kidney Na/H antiporter DNA homologous to the human growth factor activatable Na/H antiporter encodes a basolateral exchanger. The observed expression in a minority of midcortical proximal tubules could reflect a certain heterogeneity in these nephron segments.
DOI：
10.1073/pnas.87.15.5921
发表时间：
1990-08-01
影响因子：
11.1
作者：
BOYARSKY, G;GANZ, MB;BORON, WF
通讯作者：
BORON, WF