铜对蛙皮的作用：巯基的作用。

The effect of copper on frog skin: the role of sulphydryl groups.

Ferreira K T

Biochim Biophys Acta. 1978 Jul 4;510(2):298-304. doi: 10.1016/0005-2736(78)90030-5.

Abstract

Cu2+ at a concentration of 10-4 M, when applied to the external side of the frog skin produces an increase in the short-circuit current (Isc). 2. This effect was studied in skins of Rana temporaria adapted to cold,(5 degrees C) and room temperature (20 degrees C), skins of Rana pipiens adapted to cold, and the results compared with those obtained previously with Rana ribibunda. 3. The observed effect is less dependent upon the adaptation to cold than upon the functional state of the skin: skins with low short circuit currents have a bigger response to Cu2+ than skins with high Isc. 4. A species difference cannot be ruled out since skins of Rana ribibunda exhibiting high Isc give good responses to Cu2+. 5. 5,5' -dithiobis (2-nitrobenzoic acid), a sulphydryl-oxidizing reagent, produces an effect similar to that of Cu2+, and dithiothreitol an SH-reducing agent, reverses the effect of this ion. 6. Cu2+ also induces an increase in the unidirectional K+ fluxes and unmasks a net outward potassium flux. 7. The outward K+ flux induced by Cu2+ is sensitive to ouabain. 8. It is concluded that Cu2+ increases the permeability of the external barrier of the frog skin to Na+ and K+, probably by reacting with SH groups.

摘要

浓度为10⁻⁴ M的Cu²⁺ 施加于蛙皮外侧时，会使短路电流（Isc）增加。2. 在适应低温（5摄氏度）和室温（20摄氏度）的林蛙皮肤、适应低温的北美豹蛙皮肤中研究了这种效应，并将结果与之前在湖蛙中获得的结果进行了比较。3. 观察到的效应与其说是取决于对低温的适应，不如说是取决于皮肤的功能状态：短路电流低的皮肤对Cu²⁺ 的反应比短路电流高的皮肤更大。4. 由于湖蛙皮肤短路电流高且对Cu²⁺ 反应良好，因此不能排除物种差异。5. 巯基氧化试剂5,5'-二硫代双（2-硝基苯甲酸）产生与Cu²⁺ 类似的效应，而巯基还原剂二硫苏糖醇则可逆转该离子的效应。6. Cu²⁺ 还会导致单向K⁺ 通量增加，并揭示出净外向钾通量。7. Cu²⁺ 诱导的外向K⁺ 通量对哇巴因敏感。8. 得出的结论是，Cu²⁺ 可能通过与巯基反应增加蛙皮外部屏障对Na⁺ 和K⁺ 的通透性。