Activation by N-ethylmaleimide of a latent K+-Cl- flux in human red blood cells.
Activation by N-ethylmaleimide of a latent K+-Cl- flux in human red blood cells.
复制标题
N-乙基马来酰亚胺激活人红细胞中潜在的 K -Cl- 通量。
DOI：
10.1152/ajpcell.1984.246.5.c385
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Garay,RP
中科院分区：
文献类型：
--
作者：
Lauf,PK;Adragna,NC;Garay,RP
人红细胞中20%~ 50%的哇巴因不敏感的Na+和K+通量是由Cl（-）依赖性偶联转运（共转运）介导的。本文报道了巯基试剂N-乙基马来酰亚胺（NEM）对人红细胞中Cl（-）依赖的哇巴因不敏感的Na+和K+通量的影响。我们发现NEM改变了Na ~+ -K ~+共转运，并激活了一种潜伏的Cl ~（-）依赖的K ~+转运模式。这一结论是基于以下观察。1)在低浓度（0.25 mM）NEM废除布美他尼敏感的Na+外排，并没有影响，即使在10倍的浓度，对布美他尼敏感的K+外排。2)在浓度高于0.1 mM时，NEM刺激Cl（-）依赖性K+外流，高浓度的布美他尼或呋塞米仅部分抑制。在使用Rb+作为K+类似物的实验中，NEM通过刺激最大速度和降低表观外部阳离子亲和力来激活Rb+内流。这些数据表明，在人红细胞中存在化学反应基团，用于NEM激活的Cl（-）依赖性K+转运和Cl（-）依赖性Na+-K+偶联运动。
Twenty to fifty percent of the ouabain-insensitive Na+ and K+ fluxes in human red blood cells are mediated by Cl(-) -dependent coupled transport (cotransport). In this paper we report on the effect of the sulfhydryl group reagent N-ethylmaleimide (NEM) on Cl(-) -dependent ouabain-insensitive Na+ and K+ fluxes in human red blood cells. We found that NEM altered Na+ -K+ cotransport and activated a latent Cl(-) -dependent K+ transport mode normally apparently silent. This conclusion was based on the following observations. 1) At low concentrations (0.25 mM) NEM abolished the bumetanide-sensitive Na+ efflux and had no effect, even at a 10-fold higher concentration, on the bumetanide-sensitive K+ efflux. 2) At concentrations above 0.1 mM, NEM stimulated Cl(-) -dependent K+ efflux that was only partially inhibited by high concentrations of bumetanide or furosemide. In experiments using Rb+ as a K+ analogue, NEM activated Rb+ influx by stimulating the maximum velocity and lowering the apparent external cation affinity. The data suggest the presence of chemically reactive groups in human red blood cells for both Cl(-) -dependent K+ transport activated by NEM and Cl(-) -dependent coupled Na+-K+ movements.