细胞外Ba2+ 对双基因内向整流钾通道的阻断作用(PDF)
《心脏杂志》[ISSN:1009-7236/CN:61-1268/R]
- 期数:
- 2000年第5期
- 页码:
- 345-348
- 栏目:
- 论著
- 出版日期:
- 2000-10-25
文章信息/Info
- Title:
- The blocking effects of extracellular Ba2+ on the inward rectifier potassi um tandem channel
- Author(s):
- XIE An; ZANG Yi-min; ZHU Miao-zhang
- Department of Physiology, Basic Science Institute, Fourth Military Medical University, Xi'an Shaanxi 710032, China
- 分类号:
- Q424
- DOI:
- -
- 文献标识码:
- A
- 摘要:
- 目的 研究Ba2+对非洲爪蟾卵母细胞表达的双 基因内向整流钾通道(IRK1-T )的阻断作用。方法 采用双微电极电压钳(TEV)法。结果 细胞外Ba2+浓度分别为1,3,10 和100 μmol/L，K+浓度为90 mmol/L，可见Ba2+的阻断作用对IRK1-T的瞬间电流( 施加电压后1 ms)具有 浓度依赖性、时间依赖性和电压依赖性；快速开通道阻断剂Ba2+对IRK1-T 的通道开 关特性几乎无影响作用，IRK1-T对之不通透。三级指数拟合表明 细胞外Ba2+低浓 度(1和3 μmol/L)时，Ba2+与K+相互竞争同一结合位点，随着Ba2+浓度的增 加，时间常数不增加但拟 合的权数却浓度依赖性增加，所以失活过程随Ba2+浓度的增加越来越快；细胞外Ba 2+高浓度 (10和100 μmol/L)时，时间常数随Ba2+浓度的增加而减少，拟合的权数却浓度依赖 性减少， 失活过程也越来越快，说明Ba2+作用位点由通道的表面部位进入通道更深的地方。[ HTH 结论 Ba2+对IRK1-T的阻断存在两种不同的机制。
- Abstract:
- AIM The blocking effects of extracellular Ba2+ o n the inward rectifi er potassium tandem channel (IRK1-T) expressed in the Xenopus oocytes was studi e d. METHODS Two-microelectrode voltage clamp (TEV) method was used. RESULTS Ba2+ can concentration-, time- and volt age dependently block IRK1-T instanta neous currents ( 1ms after voltage applied ) when external Ba2+ concentrat ion is 1,3,10 or 100 μmol/L with 90 mmol/L potassium. Fast open channel blocker Ba 2+ almost has no effect on the open/close property of IRK1-T. IRK1-T can not per meate Ba2+. Three exponential fitting results indicate that Ba2+and K+ compete the same bi nding site in IRK1-T when external Ba2+ concentration (1 or 3 μmol/L) is lower. Time constants do not increase but the weights of the fittings concentration dependently enhance as the external Ba2+ concentration augments. So the inac tivati on becomes faster and faster as the external Ba2+ concentration increases. Time constants decrease and the weights of the fittings concentration dependently enh ance as the external Ba2+ concentration augments when external Ba2+ concentratio n (10 or 100 μmol/L) is higher. So the inactivation becomes faster and faster. It is showed that Ba2+ can go deeper in IRK1-T from the surface of the ch annel a s external Ba2+ concentration increases. CONCLUSION Two diffe rent mechanisms for external Ba2+ blocking exist.
参考文献/References
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［10］谢 安，臧益民. 细胞外Ba2+对内向整流钾通道(IRK1)的阻断作用［J］. 生 理学报, 2000，52（1）：1
备注/Memo
- 备注/Memo:
- 收稿日期：1999-09-23.基金项目：国家自然科学基金(No. 39840022)
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