| 摘要: |
| 麻痹性贝毒(Paralytic Shellfish Poisoning，PSP)毒素由石房蛤毒素(saxitoxin，STX)及其衍生物组成，目前己发现20余种，在赤潮研究、分子生物学和神经生物学基础研究、医药、军事防化等方面都有应用潜力[其结构、类型和应用见本集刊王云峰等(2003)“麻痹性贝毒毒素的应用研究进展”一文]。由于PSP毒素的稀有来源和国际社会对STX交易的禁止，限制了国内PSP毒素应用及研究的全面深入展开，因此本文作者对PSP毒素进行了制备，并采用不同方法对制备的PSP毒素进行了研究。
PSP毒素能够选择性地可逆抑制可兴奋膜的电压依赖钠离子通道的开放，从而阻止神经冲动的发生和传导，使神经、肌肉丧失兴奋性(Frace et al.，1986；Penzotti et al.，1998)。本文利用神经束膜下记录和全细胞膜片钳技术，报道了从塔玛亚历山大藻(Alexandrium tamarense)中提取的PSP粗毒素对小鼠运动神经末梢膜电流和NG108-15细胞钠离子通道的作用研究结果，并与STX标准毒素的作用结果进行了比较。
NG108-15细胞是由小鼠神经母细胞瘤和大鼠胶质细胞瘤融合的杂交细胞，经分化剂分化后，显示诸+L1196如兴奋性、合成和释放乙酰胆碱、与培养肌细胞形成突触联系等多种神经细胞的基本特性(Hamprcht，1977)和Na+、K+、Ca2+等多种离子通道，已作为神经细胞模型被广泛应用于分析药物对离子通道作用的研究(Enomoto et al.，1992； Docherty et al.，1992；Shi et al.，1993；Hu et al.，1997a；Hu et al.，1997b)；发育出具有Na+内流支持的锋电位(Hamprecht,1977)，该电位是分析作用于膜钠离子通道药物的好材料。 |
| 关键词: 麻痹性贝毒毒素 钠离子通道 运动神经末梢 |
| DOI： |
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| 基金项目:中国科学院海洋研究所调查研究报告第4364号。国家高技术研究与发展计划，8638190605号；国家自然科学基金重大项目，39790110号资助；国家自然科学基金项目，40076030号，39950001号。 |
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| STUDY ON PARALYTIC SHELLFISH POISONING TOXINS Ⅰ. THE INHIBITORY EFFECTS OF PARALYTIC SHELLFISH POISONING TOXINS FROM ALEXANDRIUM TAMARENSE ON Na+ CURRENTS AT MOTOR NERVE TERMINALS AND WHOLE CELL |
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WANG Yunfeng, YU Rencheng, LI Jun, YAN Tian, ZHOU Mingjiang
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Institute of Oceanology, The Chinese Academy of Sciences
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| Abstract: |
| Alexandrium tamarene can produce paralytic shellfish poisoning (PSP) toxins that can selectively block the voltage-gated sodium channel of many excitable membranes. Here we report the effect of PSP toxins crudely extracted from A.tamarense, on Na+M1196current at motor nerve terminals and whole cell Motor nerve terminals experiments were performed on mouse triangularis stemi nerve-muscle preparations. Presynaptic currents were picked up with a microelectrode inserted into the subendothelial space of the superficial nerve bundle under visual control using a×400 magnification water immersion objective. Patch-clamp whole cell recording configuration was used to study the effects of PSP toxins on the voltage gated Na+ current of differentiated NG 108-15 cells.
The results showed that the PSP toxins clearly inhibited the voltage-gated sodium current of the mouse motor nerve terminals and the whole NG 108-15 cell; and that the effects were partially reversible. A dose of 1.15 nmol/L ST Xeq. PSP toxins can reversibly inhibit the voltage-gated sodium current of the mouse motor nerve terminals; a dose of 4.60 nmol/L. STxeq. PSP toxins can reversibly inhibit the voltage-gated sodium current of the whole NG108-15 cell while no inhibition effect on potassium current was observed. At the same experiment conditions, the reversible inhibitions of our prepared PSP toxins were the same as that of the standard saxitoxin on sodium current of the mouse motor nerve terminals and the whole NG 108-15 cell. |
| Key words: PSP toxins Na+ current motor nerve terminals |
