5-异喹啉磺胺类化合物Fasudil对Kv7钾通道的选择性作用机制及其生理学意义

The Kv7 channel family (Kv7.1-7.5), encoded by KCNQ genes, is a family of voltage-dependent ion channels that shape cardiac action potential and stabilize neuronal membrane potential. Recently it has been found that Kv7.4 and Kv7.5 channels are abundantly expressed in a variety of vascular smooth muscles as key regulators of vascular tone, and altered Kv7 activity may have a profound bearing on pathogenesis of hypertention. However, there is still a lack of modulatory compounds selective for Kv7.4/Kv7.5 subtypes. Our previous study indicated that fasudil, a small compound of 5-isoquioline sulfonamide, dramatically enhanced Kv7.4/Kv7.5 currents but did not affect Kv7.1-Kv7.3 currents. This project is designed to clarify the selective effects and mechanisms of Fasudil on Kv7 channels and its action of vasodilation. The main research contents include: subtype selectivity of Kv7 channel modulation by Fasudil; molecular basis for selective activation of Fasudil on Kv7.4/Kv7.5 channels; the effects of Fasudil on Kv7 channels and its action of vasodilation. The research will have important significance in understanding the roles of Kv7.4/Kv7.5 channels in vascular tension modulation and in new drug target discovery.

电压门控型Kv7 (Kv7.1-7.5) 钾通道家族由KCNQ基因编码，在调节心肌动作电位及稳定神经元膜电位方面发挥重要作用。近来，Kv7.4/Kv7.5被发现在多种血管平滑肌中表达，并参与血管张力的调节，其功能异常可能参与高血压的发生。目前还没有针对Kv7.4/Kv7.5的选择性功能调节剂。我们前期研究提示5-异喹啉磺胺类化合物法舒地尔（Fasudil）可选择性激活Kv7.4/Kv7.5 通道，而对其它Kv7通道无作用。本申请将阐明Fasudil对Kv7钾通道的选择性作用机制，并研究其扩血管作用及机制。主要研究内容包括Fasudil对Kv7家族亚型选择性作用特征；决定Fasudil选择性激活Kv7.4/Kv7.5通道的分子基础；Fasudil对Kv7通道的调节作用及其舒血管作用的机制问题。本研究将对了解Kv7.4/Kv7.5通道在血管张力调控机制中的作用及作为药物作用靶点研究有重要意义。

本申请研究的核心内容是了解5-异喹啉磺胺类化合物Fasudil对Kv7钾通道的选择性调节作用、明确其作用位点及舒血管作用机制等。项目基本按照原计划执行。主要完成的研究内容包括：1：Fasudil对Kv7钾通道的调节作用及亚型选择性的研究；2：Fasudil选择性激活Kv7.4、Kv7.5通道的分子基础的研究；3：Fasudil对Kv7钾通道的调节作用及其舒血管作用的机制的研究。主要的研究结果包括：1：明确了Fasudil对表达于HEK293细胞的Kv7钾电流的选择性作用特点；2：Fasudil对表达于HEK293细胞的Kv7钾通道电导-电压关系曲线的影响；3：Fasudil对大鼠DRG神经元细胞的M电流的作用；4：Fasudil调节Kv7.4的关键位点；5：Kv7.4/Kv7.5钾通道的激活在Fasudil引发的大鼠肠系膜血管舒张中的作用。本研究证明了Fsudil是一个Kv7.4、Kv7.5钾通道选择性开放剂，这为Kv7钾通道选择性调节剂的研发及Fasudil的应用及作用机制的阐明具有重要意义。