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细胞外Ba~(2+)对内向整流钾通道的阻断作用

谢安, 臧益民

第四军医大学基础部生理学教研室.陕西,西安 710032

摘要

Ba~(2+)对IRK1的阻断存在两种不同的机制。细胞外K~(+)浓度为90mmol/L和Ba~(2+)浓度为30#mu#mol/L时,Mg~(2+)或Mn~(2+)可与Ba~(2+)争夺结合位点,随着Mg~(2+)或Mn~(2+)浓度增加,失活过程逐渐减缓,Ba~(2+)在通道中的结合点也逐渐离开通道,Mg~(2+)能而Mn~(2+)不能进入通道较深处阻断通道,说明IRK1中有多离子阻断形式。

关键词： Ba~（2+）; 内向整流钾通道; 电压箝; 爪蟾卵母细胞

Blocking effects of extracellular Ba~(2+) on the inward rectifier potassium channel

Xie An, Zang Yimin

Department of Physiology,Basic Science Institute,The Fourth Military Medical University.Xi^an 710032,Shaanxi

Abstract

Two different mechanisms may underlie the external Ba~(2+) blocking effect. External Mn~(2+) or Mg~(2+) can compete with external Ba~(2+) at the IRK1 binding site at an external Ba~(2+) concentration of 30 #mu#mol/L and K~(+) concentration of 90 mmol/L. Inactivation becomes slower and slower and Ba~(2+) is repelled from the IRK1 binding site when Mg~(2+) or Mn~(2+) concentration is further increased. Mg~(2+), but not Mn~(2+), can contact with deeper binding sites of IRK1 to block the channel, suggesting that multiple-ion blockage may exist in IRK1.

Key words: Barium;Open channel;Blocker inward;Rectifier potassium channel

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引用本文：

谢安, 臧益民. 细胞外Ba~(2+)对内向整流钾通道的阻断作用[J]. 生理学报 2000; 52 (1): .

Xie An, Zang Yimin. Blocking effects of extracellular Ba~(2+) on the inward rectifier potassium channel. Acta Physiol Sin 2000; 52 (1): (in Chinese with English abstract).