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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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Citing This Article：

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).