N-乙基马来酰亚胺对人红细胞中潜在钾氯通量的激活作用。

Activation by N-ethylmaleimide of a latent K+-Cl- flux in human red blood cells.

作者信息

Lauf P K, Adragna N C, Garay R P

出版信息

Am J Physiol. 1984 May;246(5 Pt 1):C385-90. doi: 10.1152/ajpcell.1984.246.5.C385.

DOI:10.1152/ajpcell.1984.246.5.C385

PMID:6720936

Abstract

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.

摘要

人体红细胞中20%至50%的哇巴因不敏感的Na⁺和K⁺通量是由Cl⁻依赖性协同转运介导的。在本文中，我们报告了巯基试剂N-乙基马来酰亚胺（NEM）对人体红细胞中Cl⁻依赖性哇巴因不敏感的Na⁺和K⁺通量的影响。我们发现NEM改变了Na⁺-K⁺协同转运，并激活了一种通常明显沉默的潜在Cl⁻依赖性K⁺转运模式。这一结论基于以下观察结果。1）在低浓度（0.25 mM）时，NEM消除了布美他尼敏感的Na⁺外流，即使在浓度高10倍的情况下，对布美他尼敏感的K⁺外流也没有影响。2）在浓度高于0.1 mM时，NEM刺激了Cl⁻依赖性K⁺外流，高浓度的布美他尼或呋塞米只能部分抑制这种外流。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。数据表明，在人体红细胞中存在化学反应性基团，用于NEM激活的Cl⁻依赖性K⁺转运以及Cl⁻依赖性Na⁺-K⁺协同转运。