Dissociation of E-4031 from the HERG channel caused by mutations of an amino acid results in greater block at high stimulation frequency
Dissociation of E-4031 from the HERG channel caused by mutations of an amino acid results in greater block at high stimulation frequency
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DOI：
10.1016/s0008-6363(02)00774-5
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发表时间：
2003-03-01
影响因子：
10.8
通讯作者：
Endoh, M
中科院分区：
文献类型：
--
作者：
Ishii, K;Nagai, M;Endoh, M
目的：我们报道了一种氨基酸的鉴定，这种氨基酸的突变可以减少奎尼丁对HERG通道的影响。虽然残基（647处的异亮氨酸）不在最近报道的甲磺酰苯胺结合位点，但单一浓度的E-4031 （10 muM）对1647突变体通道的作用不如野生型HERG通道。我们设计了本实验，以进一步研究647突变对甲磺酰苯胺效应的影响。方法与结果：在爪蟾卵母细胞中表达HERG通道，并采用双微电极电压钳法测定其电流。在最初研究的两个突变（1647A和1647F）中，1647F的影响更大，对dofelide和E-4031的影响不同。两个突变体通道（1647A和1647F）的dofetilide的IC50仅增加了2倍，而E-4031的IC50分别增加了6倍（1647A）和14倍（1647F）。然后用苯丙氨酸以外的芳香残基代替了1647，发现可以减少E-4031的影响。而E-4031在休息状态下与突变体通道分离，多非内酯几乎不分离。从E-4031阻滞中恢复的突变体通道在1hz时比在0.1 Hz时受到更大的抑制。结论：目前的研究结果表明，药物与HERG通道的分离会导致更大的高频阻滞。虽然突变导致E-4031解离的机制尚不确定，但值得注意的是，一种甲磺酰苯胺比另一种更容易从通道解离。(C) 2003年欧洲心脏病学会。Elsevier Science B.V.版权所有。
Objective: We have reported identification of the amino acid whose mutation reduces effects of quinidine on the HERG channel. Although the residue (isoleucine at 647) is not in the recently reported methanesulfonanilide binding site, a single concentration of E-4031 (10 muM) was less effective to 1647 mutant channels than wild type HERG channel. We designed the present experiment to further investigate influence of mutations at 647 on the effects of methanesulfonanilides. Methods and results: HERG channels were expressed in Xenopus oocytes and their currents were measured by a two-microelectrode voltage clamp method. Of the two mutations initially studied (1647A and 1647F), the 1647F had a greater influence and differentially affected the effects of dofetilide and E-4031. The IC50 for dofetilide of the two mutant channels (1647A and 1647F) was increased only 2-fold, but the IC50 for E-4031 was increased 6-fold (1647A) and 14-fold (1647F). Aromatic residues other than phenylalanine were then substituted for 1647, and found to reduce the effects of E-4031. Whereas E-4031 dissociated from the mutant channels during rested state, dofetilide little dissociated. The mutant channels that showed recovery from E-4031 block were inhibited greater at 1 Hz than at 0.1 Hz. Conclusions: The present results indicate that dissociation of a drug from the HERG channel results in greater block at high frequency. Although the mechanism by which the mutations cause the dissociation of E-4031 is uncertain, it is noteworthy that one methanesulfonanilide dissociates from the channel more easily than another. (C) 2003 European Society of Cardiology. Published by Elsevier Science B.V. All rights reserved.