Novel mechanism of blocking axonal Na<sup>+</sup>
channels by three macrocyclic polyamine analogues and two spider toxins
作者:Masuhide Yakehiro、Yasuo Furukawa、Tohru Koike、Eiichi Kimura、Terumi Nakajima、Kaoru Yamaoka、Issei Seyama
DOI:10.1038/sj.bjp.0703765
日期:2001.1
The mechanism of Na+ channel block by three macrocyclic polyamine derivatives and two spider toxins was studied with voltage clamp and internal perfusion method in squid axons.
All these chemicals specifically block Na+ channels in the open state only from the internal surface, and do not affect K+ channels.
The blocking effect is enhanced as the depolarizing pulse becomes larger. Blocked channels are unable to shift to the inactivated state.
In the case of cyclam and guanidyl‐side armed cyclam (G‐cyclam), quick release of these chemicals from the binding sites is proven by the increase in the tail current and prolongation of the time course of the off gating current. On the other hand, in the presence of N‐4 and the spider toxins, their detachment was delayed significantly.
Molecular requirements for the block of Na+ channels by these molecules are the presence of positive charge and hydrophobicity.
British Journal of Pharmacology (2001) 132, 63–72; doi:10.1038/sj.bjp.0703765
通过电压钳和内部灌流方法,在鱿鱼轴突中研究了三种 宏大环聚胺衍生物 和两种蜘蛛毒素对 Na+ 通道的阻断机制。
所有这些化学物质特异性地从内部表面仅阻断开放状态的 Na+ 通道,而不会影响 K+ 通道。
阻断效果随着去极化脉冲的增大而增强。被阻断的通道无法向失活状态转变。
在 cyclam 和胍基侧面武装的 cyclam (G- cyclam) 的情况下,通过尾电流的增加和关通道电流时间过程的延长,证明这些化学物质从结合位点快速释放。另一方面,在 N-4 和蜘蛛毒素存在下,它们的脱离被显著延迟。
这些分子阻断 Na+ 通道的分子要求是具有正电荷和疏水性。
British Journal of Pharmacology (2001) 132, 63–72; doi:10.1038/sj.bjp.0703765
(Board of Trustees of the British Pharmacological Society, 2001)