东亚钳蝎毒素多肽对河豚毒素敏感型钠电流的作用

Effects of polypeptide purified from Buthus martensi Karsch on tetrodotoxin-sensitive sodium channels in rat dorsal root ganglion neurons

目的:蝎毒素是一种神经毒素,其对周围神经系统钠通道的作用尚不十分清楚,仍有许多疑题待研究。文中研究东亚钳蝎毒素多肽224(BmK224)对大鼠背根神经节(DRG)神经元电压依赖性河豚毒素敏感型钠电流(TTX-S INa)的影响。方法:分离单个DRG神经元,应用全细胞膜片钳技术观察BmK224对TTX-S INa的影响。结果:BmK224浓度依赖性地抑制TTX-S INa,40μg/m lBmK224使TTX-S INa稳态激活和失活曲线都向超极化方向移动,复活时间延长,可激活通道数增加。结论:BmK224影响钠通道激活失活过程的作用机制可能是所含的α-蝎毒素使钠通道构象发生改变。

Objective ： Scorpion toxin is a neurotoxin, whose effects on the sodium channels of the pe- ripheral nervous system are not yet quite clear, with a lot of questions to be studied. This study aimed to investigate the effects of scorpion polypeptide purified from Buthus martensi Karsch 224 （BmK224） on the tetrodotoxin-sensitive sodium currents （TFX-S INa） in the isolated rat dorsal root ganglion （DRG） neurons. Methods： We isolated the dorsal root ganglion neurons from rats, and observed the effects of BmK224 on TTX-S INa using whole cell patch clamp recordings. Results： BmK224 blocked the whole cell TTX-S IN. in a concentration-dependent manner. At the concentration of 40 μg/ml, it induced the negative shifting of the TTX-S INa activation curve, shifted the steady-state inactivation curve to the left, delayed the recovery of TFX-S INa from inactivation, and increased the fraction of available sodium chan- nels. Conclusion ： This study suggests that BmK224 contains α- scorpion toxins, which lead to the al- teration of the conformation of sodium channels.