Shrinkage-induced activation of Na(+)-H+ exchange in barnacle muscle fibers.
Shrinkage-induced activation of Na(+)-H+ exchange in barnacle muscle fibers.
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藤壶肌纤维中 Na( )-H 交换的收缩诱导激活。
DOI：
10.1152/ajpcell.1994.266.6.c1744
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Boron,WF
中科院分区：
文献类型：
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作者：
Davis,BA;Hogan,EM;Boron,WF
我们使用 pH 微电极和内部透析检查了细胞内 pH (pHi) 值为 6.8、7.2 和 7.6 时收缩对单肌纤维 Na(+)-H+ 交换的影响。在 pHi 6.8 的正常张力条件下 (975 mosmol/kgH2O)，阿米洛利敏感的酸挤出速率 (JAmil/s) 平均为 17 microM/min。暴露于高渗溶液 (1,600 mosmol/kgH2O) 在 pHi 6.8 时 JAmil/s 增加至 304 microM/min。在pHi约7.2和7.6时，高渗性使JAmil/s从约0增加至约172μM/min(pHi 7.2)和约0至约90μM/min(pHi 7.6)。因此，在正常张力条件下，Na(+)-H+交换活性在pHi约6.8时轻微，而在较高pHi值时几乎为零。收缩刺激Na(+)-H+交换，在低pHi值下更明显。我们还研究了 Na(+)-H+ 交换器对收缩响应的 Cl- 依赖性。我们的结果表明，收缩诱导的 Na(+)-H+ 交换激活需要 Cl-，特别是细胞内 Cl-。这些结果表明，收缩既依赖于 pHi，又需要细胞内 Cl-。
We examined the effect of shrinkage on Na(+)-H+ exchange in single muscle fibers at intracellular pH (pHi) values of 6.8, 7.2, and 7.6 using pH microelectrodes and internal dialysis. Under normotonic conditions (975 mosmol/kgH2O) at pHi 6.8, the amiloride-sensitive acid-extrusion rate (JAmil/s) averaged 17 microM/min. Exposure to hypertonic solutions (1,600 mosmol/kgH2O) increased JAmil/s to 304 microM/min at pHi 6.8. At pHi approximately 7.2 and 7.6, hypertonicity increased JAmil/s from approximately 0 to approximately 172 microM/min (pHi 7.2) and approximately 0 to approximately 90 microM/min (pHi 7.6). Thus, under normotonic conditions, Na(+)-H+ exchange activity is slight at pHi approximately 6.8 and virtually nil at higher pHi values. Shrinkage stimulated Na(+)-H+ exchange, more at low pHi values. We also examined the Cl- dependence of the Na(+)-H+ exchanger's response to shrinkage. Our results indicate that shrinkage-induced activation of Na(+)-H+ exchange requires Cl-, specifically intracellular Cl-. These results establish that shrinkage is both pHi dependent and requires intracellular Cl-.