Hg^（2＋）可增强Zn^（2＋）对克氏螯虾触角神经动作电位放电的抑制作用

THE Hg￣(2+) ENHANCED INHIBITION OF Zn￣(2+) ON DISCHARGE OF ACTION POTENTIAL FROM ANTENNARY NERVE OF CRAYFISH (CAMBARUS CLARKII)

运用电生理学方法，观察Ｈｇ（２＋）、Ｚｎ（２＋）联合对克氏螯虾第一触角内侧枝神经动作电位放电的影响．当Ｈｇ（２＋）、Ｚｎ（２＋）浓度分别达到０．００００２５ｍｇ／Ｌ和０．０５ｍｇ／Ｌ时，这两种离子联合对触角神经的毒性作用潜伏期（ＴＬ）为４６．７５±２２．６９ｍｉｎ（Ｎ＝８），触角神经动作电位放电持续时间（ＤＤ）为１１５．２８±４０．９５ｍｉｎ，表示其放电频率（Ｆｎ／Ｆｌ）与作用时间关系的直线回归方程的ｂ值为－０．０８１８，与渔业水体最高允许Ｚｎ（２＋）含量０．１ｍｇ／Ｌ比较，两者间无显著差异（Ｐ＞０．１）．说明Ｈｇ２＋对Ｚｎ（２＋）的毒性具有增强效应．因此，在对有Ｈｇ（２＋）和Ｚｎ（２＋）污染的水体进行评估时，似应考虑到Ｈｇ（２＋）对Ｚｎ（２＋）毒性的增强效应．

The joint action of Hg￣(2+) and Zn￣(2+) on the discharge of action potential from nerve of antennule-inner ramus of the crayfish (Cambarus clarkii) was studied using electrophysiological method. When the concentration of Hg￣(2+) and Zn￣(2+) was 0. 000 025 mg/L and 0. 05 mg/L respectively,the toxic latency (TL)of the ions on the discharge of antennary nerve was 46. 75± 22. 69 min(N= 8),the discharge duration (DD) of the antennary nerve was 115. 28 ± 40. 95 min,and the b value of regressive lineat equation meaning the relation between its discharge frequency (F_n/F_1) and action time was - 0. 0818. These parameters were not significantly different in comparison with ρ(Zn￣(2+) )/0. 1 mg· L￣(-1) which is the highest limited concentration in water bodies of fishery(p>0. 1 ). The results indicated that the toxec action of Zn￣(2+) was enhanced by Hg￣(2+). It is suggested that this toxic joint action would be considered in evaluating complex water bodies contaminated with heavy metals.