Sodium-dependent ion cotransport in steady-state Ehrlich ascites tumor cells.
Sodium-dependent ion cotransport in steady-state Ehrlich ascites tumor cells.
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稳态艾利希腹水肿瘤细胞中钠依赖性离子共转运。
DOI：
10.1007/bf01870658
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Levinson,C
中科院分区：
文献类型：
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作者：
Levinson,C
埃利希肿瘤细胞具有阴-阳离子共转运系统，在生理稳定状态下，该系统作为一种双向交换剂发挥作用。这种共转运系统与容量调节机制（即Cl−+Na+和/或K+的耦合净摄取）相关，具有Cl−选择性和呋塞米敏感性，表明相同的机制以两种不同的模式运行。由于Na+在容量调节反应中具有重要作用，因此研究了其在稳态共转运中的作用。在不存在Na+的情况下，哇巴因不敏感的K+和DIDS不敏感的Cl−转运（KCl共转运）较低，与含呋塞米的150 mmNa+培养基中的结果相当。增加[Na+]导致K+和Cl−运输的平行增加。在约20 mm Na+时达到每种的最大速率（18至20 meq/（kg干重）·min），并保持至55 mm。因此，在1 - 55 mmNa+范围内，KCl共转运的化学计量比为1∶1。与K+和Cl−相反，呋塞米敏感的Na+转运在[Na+]超过50 mm之前是不可检测的。从50到150 mmNa+，它逐渐上升到7 meq/（kg dry wt）·min，而K+和Cl−的运输分别下降到9和16 meq/（kg dry wt）·min。因此，在150 mmNa+时，Cl−、Na+和K+之间的化学计量关系为2∶1∶1。这些结果与以下假设相一致：在稳态下运行时，依赖于Cl−的阳离子共转运系统介导KCl与KCl或NaCl与NaCl的交换;每种交换的相对比例由细胞外[Na+]决定。
The Ehrlich tumor cell possesses and anion-cation cotransport system which operates as a bidirectional exchanger during the physiological steady state. This cotransport system, like that associated with the volume regulatory mechanism (i.e. coupled net uptake of Cl−+Na+and/or K+) is Cl−-selective and furosemide-sensitive, suggesting the same mechanism operating in two different modes. Since Na+has an important function in the volume regulatory response, its role in steady-state cotransport was investigated. In the absence of Na+, ouabain-insensitive K+and DIDS-insensitive Cl−transport (KCl cotransport) are low and equivalent to that found in 150mmNa+medium containing furosemide. Increasing the [Na+] results in parallel increases in K+and Cl−transport. The maximum rate of each (18 to 20 meq/(kg dry wt)·min) is reached at about 20mmNa+and is maintained up to 55mm. Thus, over the range 1 to 55mmNa+the stoichiometry of KCl cotransport is 1∶1. In contrast to K+and Cl−, furosemide-sensitive Na+transport is undetectable until the [Na+] exceeds 50mm. From 50 to 150mmNa+, it progressively rises to 7 meq/(kg dry wt)·min, while K+and Cl−transport decrease to 9 and 16 meq/(kg dry wt)·min, respectively. Thus, at 150mmNa+the stoichiometric relationship between Cl−, Na+and K+is 2∶1∶1. These results are consistent with the proposal that the Cl−-dependent cation cotransport system when operating during the steady state mediates the exchange of KCl for KCl or NaCl for NaCl; the relative proportion of each determined by the extracellular [Na+].