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K+通道亚型Kv4.3在调节心肌细胞动作电位的幅度与时程方面具有重要作用,是治疗心律失常的有效作用靶点,但目前世界上该通道的特异性抑制剂非常缺乏。敬钊毒素-V(Jingzhaotoxin-V,JZTX-V)是从敬钊缨毛蜘蛛粗毒中纯化到的一种新型肽类神经毒素,能够部分抑制大鼠背根神经节细胞上的瞬时外向K+电流,其半数有效抑制浓度(IC50值)为52.3nmol/L。为了研究JZTX-V对Kv4.3通道的作用,本实验通过多肽固相化学合成的方法得到JZTX-V,并用双电极杆电压钳技术检测JZTX-V对表达在非洲爪蟾卵母细胞上的Kv4.3通道电流的作用。结果显示,JZTX-V能够完全抑制Kv4.3通道电流,并且这种抑制作用具有浓度依赖性和时间依赖性,其IC50值为425.1nmol/L,JZTX-V还能够使通道的电流-电压关系曲线和稳态失活曲线分别向去极化方向漂移大约29mV和10mV,改变Kv4.3通道的动力学特征,因此我们推测JZTX-V是一种Kv4.3通道门控调制毒素。以上研究结果对于开发心肌Kv4.3通道的分子探针及以Kv4.3通道为靶点的药物设计具有借鉴作用。
The K + channel subtype Kv4.3 plays an important role in regulating the amplitude and duration of action potential of cardiomyocytes and is an effective target for the treatment of arrhythmia. However, there are currently very few specific inhibitors of this channel in the world. Jingzhaotoxin-V (JZTX-V) is a new type of peptide neurotoxin purified from the crude poison of Jing Zhao Ying Spider, which can partially inhibit the transient outward K + Current, the half effective inhibitory concentration (IC50 value) of 52.3nmol / L. In order to study the effect of JZTX-V on Kv4.3 channel, JZTX-V was obtained by peptide solid-phase chemical synthesis in this experiment. JZTX-V was detected by double-pole voltage clamp technique on Xenopus laevis oocytes Kv4.3 channel current role. The results showed that JZTX-V could completely inhibit Kv4.3 channel current, and the inhibitory effect was concentration-dependent and time-dependent with an IC50 value of 425.1nmol / L. JZTX-V could also make the channel current-voltage relationship The curves and steady-state inactivation curves drift approximately 29 mV and 10 mV, respectively, in the direction of depolarization, changing the kinetic characteristics of the Kv4.3 channel, so we hypothesize that JZTX-V is a Kv4.3 channel-gated toxin. The above results provide reference for the development of molecular probes for myocardial Kv4.3 channel and drug design targeting Kv4.3 channel.