Cellular responses to steroids in the enhancement of Na+ transport by rat collecting duct cells in culture. Differences between glucocorticoid and mineralocorticoid hormones.
Cellular responses to steroids in the enhancement of Na+ transport by rat collecting duct cells in culture. Differences between glucocorticoid and mineralocorticoid hormones.
复制标题
细胞对类固醇的反应增强培养中大鼠集合管细胞的钠转运。
DOI：
10.1172/jci116003
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Stokes,JB
中科院分区：
文献类型：
--
作者：
Laplace,JR;Husted,RF;Stokes,JB
最近发现，盐皮质激素 (MC) 和糖皮质激素 (GC) 激素均可刺激培养的哺乳动物集合管细胞对电 Na+ 的吸收。在大鼠内髓集合管 (IMCD) 细胞的原代培养物中，与 MC 或 GC 激动剂一起孵育 24 小时可刺激 Na+ 转运约三倍。我们现在已经确定效果不是相加的，但时间进程不同。由于已知醛固酮会刺激皮质集合管主细胞中的柠檬酸合酶、Na+/K+ ATP酶活性和哇巴因结合，因此我们确定了类固醇对 IMCD 细胞中这些参数的影响。 MC 和 GC 激动剂均使柠檬酸合酶活性略有增加。 Na+/K+ ATP酶活性没有增加，但任一激动剂的特异性哇巴因结合增加了两倍以上。为了确定顶端 Na+ 进入在类固醇诱导效应中的作用，使用了 Na+ 通道抑制剂苯扎米尔。苯扎米尔不会改变任何一种类固醇对柠檬酸合酶活性的刺激。相比之下，苯扎米尔可以阻止 GC 刺激哇巴因结合，而 MC 刺激则不然。我们得出的结论是，MC 和 GC 激素增加 Na+ 转运的方式存在差异。两者似乎都会使泵移位（或激活）到基底外侧膜中。 GC 刺激泵易位需要增加 Na+ 进入，而 MC 刺激则不需要。图像
It has recently been discovered that both mineralocorticoid (MC) and glucocorticoid (GC) hormones can stimulate electrogenic Na+ absorption by mammalian collecting duct cells in culture. In primary cultures of rat inner medullary collecting duct (IMCD) cells, 24-h incubation with either MC or GC agonist stimulates Na+ transport approximately threefold. We have now determined that the effects were not additive, but the time courses were different. As aldosterone is known to stimulate citrate synthase, Na+/K+ ATPase activity, and ouabain binding in cortical collecting duct principal cells, we determined the effects of steroids on these parameters in IMCD cells. MC and GC agonists both produced a small increase in citrate synthase activity. There was no increase in Na+/K+ ATPase activity but specific ouabain binding was increased more than two-fold by either agonist. To determine the role of apical Na+ entry in the steroid-induced effects, the Na+ channel inhibitor, benzamil, was used. Benzamil did not alter the stimulation of citrate synthase activity by either steroid. In contrast, GC stimulation of ouabain binding was prevented by benzamil, whereas MC stimulation was not. We conclude that there are differences in the way that MC and GC hormones produce an increased Na+ transport. Both appear to produce translocation (or activation) of pumps into the basolateral membrane. GC stimulation of pump translocation requires increased Na+ entry whereas MC stimulation does not.Images