Yoshioka T, Kawai K, Katsuki Y
Jpn J Physiol. 1976;26(5):441-53. doi: 10.2170/jjphysiol.26.441.
The stimulating effect on the receptor organ of various mono-and divalent metallic ions on the lateral-line nerve of tadpoles was studied. The orders of the effectiveness were Ag + greater than T1+ greater than K+==Na+ greater than Li for monovalent ions and Sr2+ greater than Mg2+ greater than or equal too Ba2+ greater than Cd2+ greater than or equal too Co2+ greater than Mn2+ greater than Zn2+ for divalent ions. Both agree well with the order of Pearson's softness parameter for monovalent ions and Edwards' modified parameter for divalent ones. All sorts of divalent cations exhibited suppressive effects on the stimulating effect of the monovalent cations when they were applied together with the monovalent cations. A simple selection rule was found for the suppressive effect. The stimulating effect of Na+ or K+ was suppressed by all sorts of divalent cations. But the effect of Ag+ was suppressed by Cd2+, but not by Mg2+ nor by Ca2+. In order to remove the Ag+ effect, a dilute solution of DTT was used, although the effect of K+ or Na+ was removed easily by rinsing with distilled water. From these results the receptive mechanism of the endorgan was thought to be chemical adsorption of ions in the receptor cell membrane. Based on the principle of "hard and soft acid and base", it is suggested that there are two types of binding sites for the ions on the membrane, a soft site and a hard one.
研究了各种单价和二价金属离子对蝌蚪侧线神经受体器官的刺激作用。单价离子的有效性顺序为：Ag⁺＞Tl⁺＞K⁺=Na⁺＞Li⁺；二价离子的有效性顺序为：Sr²⁺＞Mg²⁺≥Ba²⁺＞Cd²⁺≥Co²⁺＞Mn²⁺＞Zn²⁺。这与单价离子的皮尔逊软度参数顺序和二价离子的爱德华兹修正参数顺序都非常吻合。当所有二价阳离子与单价阳离子一起应用时，它们对单价阳离子的刺激作用均表现出抑制作用。发现了一个关于抑制作用的简单选择规则。Na⁺或K⁺的刺激作用被所有二价阳离子抑制。但是Ag⁺的作用被Cd²⁺抑制，而不被Mg²⁺或Ca²⁺抑制。为了消除Ag⁺的影响，使用了二硫苏糖醇稀溶液，而K⁺或Na⁺的影响通过用蒸馏水冲洗很容易消除。从这些结果推测，终末器官的感受机制是受体细胞膜中离子的化学吸附。基于“软硬酸碱”原理，表明膜上离子有两种结合位点，一种软位点和一种硬位点。
