HCO3(-)离子对大鼠脑膜中ATP依赖的GABA(A)受体偶联Cl(-)通道的影响。

Effect of HCO3(-) ions on the ATP-dependent GABA(A) receptor-coupled Cl(-) channel in rat brain plasma membranes.

作者信息

Menzikov S A, Karpova M N, Kalinina M V

机构信息

State Research Institute of General Pathology and Pathological Physiology, Russian Academy of Medical Sciences, Moscow, Russia.

出版信息

Bull Exp Biol Med. 2011 Nov;152(1):38-42. doi: 10.1007/s10517-011-1448-z.

DOI:10.1007/s10517-011-1448-z

PMID:22803035

Abstract

We studied the effect of Cl(-) (10-75 mM) and HCO(3)(-) ions (10-25 mM) on the ATP-dependent GABA(A) receptor-coupled Cl(-) channel (Cl(-)-ATPase) in rat brain plasma membranes. The total enzyme activity was detected in the presence of both anions at a Cl(-)/ HCO(3)(-) ratio of 5:1 (Cl(-), HCO(3)(-)-ATPase). Specific inhibitors of P-type transport ATPases (N-ethylmaleimide, o-vanadate, and oligomycin) suppressed Cl(-), HCO(3)(-)-ATPase, while the Cl(-)- and HCO(3)(-)-ATPase activities were low sensitive to these ligands. Bicuculline abolished the activating effect of Cl(-) and HCO(3)(-) ions on the enzyme. HCO(3)(-) ions had no effect on the ATP-dependent Cl(-) transport into proteoliposomes (with the involvement of reconstituted ATPase). In experiment with Cl(-)-preloaded liposomes, addition of HCO(3)(-) ions to the incubation medium caused the reversion of Cl(-) transport (ion efflux from liposomes). Our results suggest that HCO(3)(-) ions play an important role in the modification of properties of the ATP-dependent GABA(A) receptor-coupled Cl(-) channel and GABA(A) receptor-induced Cl(-)/ HCO(3)(-) exchange. These ions are probably involved in GABA(A) receptor-induced Cl(-)/ HCO(3)(-) exchange in neuronal membranes.

摘要

我们研究了氯离子（10 - 75 mM）和碳酸氢根离子（10 - 25 mM）对大鼠脑细胞膜中ATP依赖性GABA(A)受体偶联氯离子通道（Cl(-)-ATPase）的影响。在两种阴离子存在且Cl(-)/HCO(3)(-)比例为5:1的情况下检测到总酶活性（Cl(-), HCO(3)(-)-ATPase）。P型转运ATP酶的特异性抑制剂（N - 乙基马来酰亚胺、偏钒酸盐和寡霉素）抑制了Cl(-), HCO(3)(-)-ATPase，而Cl(-)-和HCO(3)(-)-ATPase活性对这些配体低敏感。荷包牡丹碱消除了氯离子和碳酸氢根离子对该酶的激活作用。碳酸氢根离子对ATP依赖性氯离子转运到蛋白脂质体中（涉及重组ATP酶）没有影响。在对预先加载氯离子的脂质体进行的实验中，向孵育培养基中添加碳酸氢根离子导致氯离子转运逆转（氯离子从脂质体流出）。我们的结果表明，碳酸氢根离子在修饰ATP依赖性GABA(A)受体偶联氯离子通道的特性以及GABA(A)受体诱导的Cl(-)/HCO(3)(-)交换中起重要作用。这些离子可能参与神经元膜中GABA(A)受体诱导的Cl(-)/HCO(3)(-)交换。