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蝎毒耐热蛋白对大鼠海马神经元钠通道的抑制作用

张晓芸, 王越, 张健, 王靖宇, 赵杰, 张万琴, 李韶

大连医科大学生理学教研室,脑疾病研究所.辽宁,大连 116027

摘要

应用全细胞膜片钳技术观察蝎毒耐热蛋白（scorpion venom heat resistant protein，SVHRP）对急性分离大鼠海马神经元电压依赖性钠通道的影响。结果表明，急性分离大鼠海马神经元产生的河豚毒素（tetrodotoxin，TTX）敏感的电压依赖性钠电流被SVHRP浓度依赖性地抑制，半数抑制浓度为（0.0034±0.0004）#mu#g／mL，Hill常数为0.4361±0.0318；SVHRP可使钠通道稳态激活曲线向电压的正方向移动，正常TTX敏感的钠通道的半数激活电压（V_(1/2)）为（--34.38±0.62）mV（n=16），给予0.1#mu#g／mL的SVHRP后V_(1/2)为（--23.96±0.41）mV（{sl n}=8，{sl P}<0.05），斜坡因子（#kappa#）由正常的4.52±0.52变为3.73±0.08（{sl n}=8，{sl P}<0.05）。SVHRP亦能改变电压依赖性钠通道的稳态失活曲线，使其向电位的负方向移动，SVHRP处理前钠通道半数失活电压（V_(1/2)）为（--32.60±1.52）mV，#kappa#为6.73±0.51（{sl n}=16）；0.1#mu#g／mL的SVHRP处理后V_(1/2)变为（--50.69±2.55）mV（{sl n}=8，{sl P}<0.01），#kappa#为5.49±0.72（{sl n}=8，{sl P}<0.05）。结果提示，SVHRP能抑制电压依赖性钠电流，改变钠通道的动力学特性，抑制其激活，促进其失活，从而影响神经元的兴奋性，这可能是其抗癫痫的机制之一。

关键词： 蝎毒耐热蛋白; 全细胞膜片钳; 钠通道; 海马神经元

Inhibition of sodium channels in acutely isolated hippocampal neurons by scorpion venom heat resistant protein

Zhang Xiaoyun, Wang Yue, Zhang Jian, Wang Jingyu, Zhao Jie, Zhang Wanqin, Li Shao

Department of Physiology, Institute of Brain Disorder, Dalian Medical University.Dalian 116027,Liaoning

Abstract

The effects of scorpion venom heat resistant protein （SVHRP） on sodium channel were studied in freshly isolated hippocampal neurons in rat using the whole-cell patch-clamp technique. The results indicated that tetrodotoxin-sensitive voltage-dependent sodium current in hippocampal neurons was inhibited by SVHRP in a dose-dependent manner. The half-inhibition concentration （IC50） was （0.0034±0.0004） #mu#g/mL, Hill constant （n） was 0.4361±0.0318. After SVHRP application, a clear shift of the activation curve of Na~(+) channel was shown towards more depolarized potential, resulting in channel opening at more positive membrane potentials. In the presence of 0.1 #mu#g/mL SVHRP, the voltage for half-activation （V_(1/2)） and the slope factor of the activation curve were （-23.96±0.41） mV and 3.73±0.08 （n=8, P<0.05） compared with the control recordings of （-34.38±0.62） mV and 4.52±0.52 （n=16）, respectively. Averaged and normalized curve of steady-state inactivation of Na~(+) channel was shifted towards negative potential after treatment of 0.1 and 0.01 #mu#g/mL SVHRP. In the presence of 0.1 #mu#g/mL SVHRP, the voltage for half-inactivation （V_(1/2)） and the slope factor determined by a sigmoid fit of the inactivation curve were （-50.69±2.55） mV （n=8, P<0.01） and 5.49±0.72 （n=8, P<0.05） compared with the control recordings of （-32.60±1.52） mV and 6.73±0.51 （n=16）, respectively. These results suggest that SVHRP blocks the voltage-dependent sodium currents and alters the sodium channel kinetics to decrease the excitability of neurons. This might be an interpretation for the antiepileptic effects of SVHRP.

Key words: scorpion venom heat resistant protein;whole-cell patch-clamp;sodium channels;hippocampal neuron

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引用本文：

张晓芸, 王越, 张健, 王靖宇, 赵杰, 张万琴, 李韶. 蝎毒耐热蛋白对大鼠海马神经元钠通道的抑制作用[J]. 生理学报 2007; 59 (3): 278-284.

Zhang Xiaoyun, Wang Yue, Zhang Jian, Wang Jingyu, Zhao Jie, Zhang Wanqin, Li Shao. Inhibition of sodium channels in acutely isolated hippocampal neurons by scorpion venom heat resistant protein. Acta Physiol Sin 2007; 59 (3): 278-284 (in Chinese with English abstract).