Yoshioka T, Asanuma A, Yanagisawa K, Katsuki Y
Jpn J Physiol. 1978;28(5):557-67. doi: 10.2170/jjphysiol.28.557.
Stimulating effects of various mono- and divalent cations on the lateral-line organ were theoretically analysed by use of the site binding chemical adsorption model with the principle of "hard and soft acids and bases." A linear relation between the softness parameter and the logarithmic value of the intrinsic association constant was obtained for the cations of Na, K, Tl, Ag, Ca, Mg, and Cd. The order of effectiveness of these cations agreed with that of the intrinsic association constant. Using these values for various cations, the critical concentration of divalent cations necessary to supress the effect of monovalent cations was calculated and compared with the experimental values. The calculated concentration of the hard divalent cations (Ca2+, Mg2+), which suppressed the effect of the hard monovalent cations (K+, Na+), agreed with the experimental concentration. The same relations were obtained between the suppressive effect of a soft divalent and a soft monovalent cation. The chemical adsorption of Ag+ on the lateral-line organ of Xenopus laevis was investigated by using a transmission electron microscope equipped with an X-ray microprobe analyser in order to get further confirmation of this model. Silver applied to the lateral-line organ was found around a kinocilium but not in the hair cells of the lateral-line organ. Thus chemical adsorption of the cation on the surface of the receptor membrane was directly proved.
利用“硬软酸碱”原理的位点结合化学吸附模型，从理论上分析了各种单价和二价阳离子对侧线器官的刺激作用。对于钠、钾、铊、银、钙、镁和镉的阳离子，得到了软度参数与固有缔合常数对数值之间的线性关系。这些阳离子的有效性顺序与固有缔合常数的顺序一致。利用各种阳离子的这些值，计算了抑制单价阳离子作用所需的二价阳离子的临界浓度，并与实验值进行了比较。抑制硬单价阳离子（钾离子、钠离子）作用的硬二价阳离子（钙离子、镁离子）的计算浓度与实验浓度一致。软二价阳离子和软单价阳离子的抑制作用之间也得到了相同的关系。为了进一步证实该模型，利用配备X射线微探针分析仪的透射电子显微镜研究了银离子在非洲爪蟾侧线器官上的化学吸附。施加到侧线器官上的银在动纤毛周围被发现，但不在侧线器官的毛细胞中。因此，直接证明了阳离子在受体膜表面的化学吸附。
