On the mechanism of bicarbonate exit from renal proximal tubular cells.
On the mechanism of bicarbonate exit from renal proximal tubular cells.
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关于碳酸氢盐从肾近端肾小管细胞排出的机制。
DOI：
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发表时间：
1996
影响因子：
19.6
通讯作者：
Eberhard Frömter
中科院分区：
文献类型：
--
作者：
G. Seki;Salvatore Coppola;K. Yoshitomi;B.;I. Samaržija;S. Müller;Eberhard Frömter
在此，我们比较了在体大鼠肾脏近端肾小管上皮细胞的电生理测量结果，以及在体外对兔和大鼠肾小管上皮细胞的电生理测量结果。根据碳酸酐酶抑制剂在体内和体外制剂中的不同作用，我们得出结论：NaHCO3在体内是以Na(+)-CO3(2-)-HCO3-共转运的方式通过基底膜，而在经典的体外制剂中是以Na(+)-HCO3(-)-HCO3-的共转运方式进行的。前者，而不是后者，其特征是产生局部不平衡的pH/CO3(2-)浓度，如果膜结合的碳酸酐酶被抑制，这些浓度就会与通量相反。为了支持这一结论，我们发现，在体内，HCO3-对Na+的化学计量比为3：1(因为每个运输的CO3(2-)最终产生2个HCO3-离子)的整体转运功能，但在体外为2：1。这是从各种测量中推导出来的，其中包括超Nernstian和反向Nernstian，它们是离子浓度变化的电势响应，这是阳离子-阴离子共转运体的特征，但在经典电化学中是未知的。体内和体外不同的转运方式表明，与体内的近端小管相比，分离的近端小管存在功能缺陷。
We compare here the results of electrophysiological measurements on proximal tubular cells performed on rat kidney in vivo and on isolated rabbit and rat tubules in vitro. Based on different effects of carbonic anhydrase inhibitors in the in vivo and in vitro preparation, we conclude that NaHCO3 cotransport across the basolateral cell membrane functions as Na(+)-CO3(2-)-HCO3- cotransport in vivo, but as Na(+)-HCO3(-)-HCO3- cotransport in the classical in vitro preparation. The former, but not the latter, transport mode is characterized by generation of local disequilibrium pH/CO3(2-) concentrations that oppose fluxes if membrane-bound carbonic anhydrase is inhibited. In support of this conclusion, we find that overall transport functions with a HCO3- to Na+ stoichiometry of 3:1 in vivo (since each transported CO3(2-) eventually generates 2 HCO3- ions), but 2:1 in vitro. This has been deduced from various measurements, among them super-Nernstian and reverse nernstian, potential responses to changing ion concentrations which are characteristic of obligatorily coupled cation-anion cotransporters, but are not known in classical electrochemistry. The different transport modes in vivo and in vitro suggest that isolated proximal tubules have functional deficits compared to proximal tubules in vivo.
DOI：
10.1172/jci113980
发表时间：
1989-03
期刊：
The Journal of clinical investigation
影响因子：
--
作者：
M. Soleimani;P. Aronson
通讯作者：
M. Soleimani;P. Aronson
DOI：
10.1016/s0021-9258(18)51463-0
发表时间：
1989-11
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
M. Soleimani;P. Aronson
通讯作者：
M. Soleimani;P. Aronson