Expression of Na(+)-H+ exchange and ATP-dependent proton extrusion in growing rat IMCD cells.
Expression of Na(+)-H+ exchange and ATP-dependent proton extrusion in growing rat IMCD cells.
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Na( )-H 交换和 ATP 依赖性质子挤出在生长的大鼠 IMCD 细胞中的表达。
DOI：
10.1152/ajpcell.1990.258.3.c416
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Seifter,JL
中科院分区：
文献类型：
--
作者：
Stanton,RC;Boxer,DC;Seifter,JL
作为尿酸化的最后一步，内髓集合管（IMCD）被认为通过H（+）-转位腺苷三磷酸酶（H（+）-ATP酶）将质子分泌到肾小管腔中。然而，最近的研究也表明IMCD细胞中存在Na（+）-H+交换活性。尽管IMCD细胞中反向转运蛋白的生理功能尚不清楚，但在其他细胞培养系统中Na（+）-H+交换的激活已被认为与细胞生长过程密切相关。因此，Na（+）-H+交换的存在可能与这些细胞的生长阶段有关。为了研究生长中的IMCD细胞的细胞内pH（pHi）调节，我们使用pH敏感染料2 '，7'-双（羧乙基）-5，6-羧基荧光素乙酰氧基甲酯（BCECF/AM）通过显微荧光法研究了Na（+）依赖性和Na（+）非依赖性机制的质子转运。通过[3 H]胸苷还原定义的活跃生长的细胞证明了酸负荷后阿米洛利敏感的Na（+）依赖性pHi恢复。在不存在Na+的情况下没有明显的pHi恢复，表明Na（+）-H+交换对于pHi恢复的重要性。然而，当在静止细胞中进行评价时，Na（+）依赖性pHi恢复似乎减少。相反，存在Na（+）-非依赖性pHi恢复，其可通过ATP耗竭和1 mM N-乙基马来酰亚胺恢复，表明H（+）-ATP酶的功能。这些发现表明，在IMCD细胞的快速生长期，表达Na（+）依赖的质子排出活性（Na（+）-H+交换），而不是Na（+）非依赖的质子排出活性，而更多的静止细胞表达Na（+）非依赖的ATP依赖的质子排出活性和可能活性较低的Na（+）-H+交换。
As the last step of urinary acidification, the inner medullary collecting duct (IMCD) is thought to secrete protons into the tubular lumens by means of a H(+)-translocating adenosinetriphosphatase (H(+)-ATPase). However, recent studies have also shown the existence of Na(+)-H+ exchange activity in IMCD cells. Although the physiological function of the antiporter in IMCD cells is unknown, activation of Na(+)-H+ exchange in other cell-culture systems has been suggested to be closely associated with the process of cell growth. Thus presence of Na(+)-H+ exchange may relate to the growth phase of these cells. To examine intracellular pH (pHi) regulation in growing IMCD cells, we studied proton transport by Na(+)-dependent and Na(+)-independent mechanisms by microfluorimetry using the pHi-sensitive dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester (BCECF/AM). Actively growing cells, defined by [3H]thymidine incorporations, demonstrated an amiloride-sensitive Na(+)-dependent pHi recovery after an acid load. No pHi recovery was evident in the absence of Na+, indicating the importance of Na(+)-H+ exchange for pHi recovery. However, when evaluated in quiescent cells, Na(+)-dependent pHi recovery appeared to be diminished. Instead, a Na(+)-independent pHi recovery which was inhibitable by ATP depletion and by 1 mM N-ethylmaleimide was present, suggesting function of a H(+)-ATPase. These findings indicate that Na(+)-dependent proton extrusion activity (Na(+)-H+ exchange) but not Na(+)-independent proton extrusion activity is expressed during the rapid growth phase of IMCD cells, whereas the more quiescent cells express Na(+)-independent ATP-dependent proton extrusion activity and a possibly less active Na(+)-H+ exchanger.