Barium block of the muscarinic potassium current in guinea-pig atrial cells
发布时间：2025-04-30
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- 发布时间：
- 2025-04-30
- 论文名称：
- Barium block of the muscarinic potassium current in guinea-pig atrial cells
- 发表刊物：
- Pflugers Arch
- 摘要：
- Block of the muscarinic K+ current (iK,ACh) by Ba2+ has been studied in guinea-pig atrial cells using the whole-cell patch-clamp technique. The dose-response curve for the block of iK,ACh can be fitted assuming that a muscarinic K+ channel is blocked when a single Ba2+ ion binds to it (apparent dissociation constant, Kd = 125 microM at 0 mV). Block was voltage and time dependent. The voltage dependence can be explained by Ba2+ binding to a site within the pore of the channel, 36% across the width of the membrane electric field (from the outside). Raising the bathing K+ concentration reduced Ba2+ block of iK,ACh, which suggests that Ba2+ and K+ compete for a common binding site. When Ba2+ was added during an exposure to ACh (muscarinic K+ channel open), block of iK,ACh developed rapidly, but when Ba2+ was added prior to an exposure to ACh (muscarinic K+ channel closed), little block of iK,ACh was evident when ACh was first applied. This suggests that when the muscarinic K+ channel is closed in the absence of ACh, Ba2+ does not have access to the binding site within the pore of the channel. In conclusion, Ba2+ block of iK,ACh is concentration, voltage, time, K+ and state dependent.
- 合写作者：
- Zang WJ, Yu XJ, Boyett MR
- 卷号：
- 430(3)
- 页面范围：
- 348-357
- 是否译文：
- 否
- 发表时间：
- 1995-07-21