Beauwens R, Crabbé J
J Clin Invest. 1983 Sep;72(3):928-34. doi: 10.1172/JCI111064.
The sodium-transporting activity of toad skin is stimulated in vitro with aldosterone in the absence of energy-providing substrate; it can be stimulated further upon addition of glucose after prolonged (overnight) incubation. The magnifying effect exerted by glucose in these conditions could be blocked by inhibitors of ribonucleic acid and protein biosynthesis. In addition, exposure to cycloheximide prevented the increase in thermodynamic affinity resulting from aldosterone treatment. A synthetic 19-nor steroid, (RU 24411), dimethyl-2,2-hydroxy-21-nor-19-pregnene-4-dione-3,20, also stimulated sodium transport by toad skin incubated in the absence of glucose, but there was no magnifying effect of this substrate. Furthermore, there was no change in thermodynamic affinity with RU 24411. Therefore, the magnifying effect seen with glucose and the increase in thermodynamic affinity are not necessarily integral parts of the response of sodium-transporting epithelial to "mineralocorticoids."
在没有供能底物的情况下，蟾蜍皮肤的钠转运活性在体外受到醛固酮的刺激；经过长时间（过夜）孵育后，添加葡萄糖可进一步刺激该活性。在这些条件下，葡萄糖所发挥的放大作用可被核糖核酸和蛋白质生物合成的抑制剂阻断。此外，用环己酰亚胺处理可阻止醛固酮处理导致的热力学亲和力增加。一种合成的19-去甲甾体（RU 24411），即二甲基-2,2-羟基-21-去甲-19-孕烯-4-二酮-3,20，也能刺激在无葡萄糖条件下孵育的蟾蜍皮肤的钠转运，但该底物没有放大作用。此外，使用RU 24411后热力学亲和力没有变化。因此，葡萄糖所见的放大作用和热力学亲和力的增加不一定是钠转运上皮对“盐皮质激素”反应的组成部分。
