Coles J A
Université de Genève, Département d'Oto-Neuro-Ophtalmologie, Switzerland.
Pflugers Arch. 1988 Mar;411(3):339-44. doi: 10.1007/BF00585125.
A negative bias potential of up to -80 mV applied to the back of a liquid membrane ion-selective microelectrode containing classical "K+" ion-exchanger was found to make it more selective for millimolar concentrations of K+ over micromolar concentrations of choline, tetramethylammonium, tetraethylammonium and 5-hydroxytryptamine. Conversely, positive bias potential increased severalfold the sensitivity to micromolar concentrations of these ions while decreasing the sensitivity to K+. An increase in response amplitude for millimolar changes of ion concentration was also observed in neutral carrier electrodes for Na+, K+ and Ca2+ with negative bias potential. The various ions caused the resistances of the electrodes to change; these resistance changes contributed to the changes in response amplitude, but there were additional, unexplained, factors. The phenomenon was used to test if the signal from a K+ ion-exchanger microelectrode in extracellular space in bee retina was contaminated by substances other than K+.
研究发现，对于含有经典“K⁺”离子交换剂的液膜离子选择性微电极，在其背面施加高达 -80 mV 的负偏置电位，可使其对毫摩尔浓度的 K⁺ 比对微摩尔浓度的胆碱、四甲基铵、四乙基铵和 5-羟色胺具有更高的选择性。相反，正偏置电位使对这些离子微摩尔浓度的灵敏度提高了几倍，同时降低了对 K⁺ 的灵敏度。在具有负偏置电位的用于 Na⁺、K⁺ 和 Ca²⁺ 的中性载体电极中，也观察到离子浓度毫摩尔变化时响应幅度的增加。各种离子导致电极电阻发生变化；这些电阻变化促成了响应幅度的变化，但还存在其他无法解释的因素。该现象被用于测试蜜蜂视网膜细胞外空间中 K⁺ 离子交换剂微电极发出的信号是否被 K⁺ 以外的物质污染。
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