糖皮质激素对肝细胞内游离钙的作用

应用钙离子荧光指示剂ｆｕｒａ－２，对糖皮质激素（Ｇｌｕｃｏｃｏｒｔｉｃｏｉｄ，ＧＣ）是否影响肝细胞内游离钙（Ｉｎｔｒａｃｅｌｌｕｌａｒ　ｆｒｅｅ　ｃａｌｃｉｕｍ，［Ｃａ２＋］ｉ作了初步探讨。结果发现，ＧＣ在短期内能升高肝细胞［Ｃａ２＋］ｉ，水平，并具有明显的量效关系。以１．０μｍｏｌ／Ｌ的Ｃｏｒｔｉｓｏｌ和１０．０μｍｏｌ／Ｌ的Ｄｅｘａｍｅｔｈａｓｏｎｅ效果最好。加入１．０μｍｏｌ／Ｌ的Ｃｏｒｔｉｓｏｌ０．２５ｍｉｎ即可引起肝细胞［Ｃａ２＋］ｉ的明显升高，到１０分钟时效应达高峰。此时与静息状态的肝细胞［Ｃａ２＋］ｉ水平相比，胞浆内游离钙升高了近３倍；与相应对照组比较，胞浆内游离钙升高具有明显的统计学意义，Ｐ＜０．０１。ＲＵ４８６为一种人工合成的糖皮质激素受体（Ｇｌｕｃｏｃｏｒｔｉｃｏｉｄ　ｒｅｃｅｐｔｏｒ，ＧＲ）的拮抗剂，它可以取消ＧＣ升高肝细胞［Ｃａ２＋］ｉ的效应，提示ＧＣ升高肝细胞内［Ｃａ２＋］ｉ可能与ＧＲ介导有一定关系。鉴于ＧＣ升高［Ｃａ２＋］ｉ时间较短，推测与肝细胞膜ＧＲ的非基因快速调节作用影响钙离子通道有关。

Effects of Glucocorticoids Hormone on Intracellular Free Calcium in Liver Cells

By using calcium fluorescent indicator fura-2, we studied the effects of glucocorticoid (GC) on intracellular free calcium Ca2+]i in rat liver cells. The results indicated that GC increased the liver cells Ca2+]i, and showed an obvious dose-effects relationship. The highest effects was obtained by 1. 0μmol/L cortisol or by 10. 0μmol/L DEX. After GC was added, it can be observed that the liver cell Ca2+]i increased at 0. 25 minutes; and the Ca2+]i reached the highest peak at 10 minutes. Its value was almost 3-folds higher than the basic level. In comparison with the control group, the elevated Ca2+]i by GC showed obvious statistical significance, P<0. 01. RU486, a synthetic glucocorticoid receptor (GR) competitive antagonist,had showed the inhibitory effects of GC on liver cell Ca2+]i, which indicated that the effects of GC may have some relation with GR. As the GC can increase rat liver cell Ca2+]i very quickly, therefore we supposed that it might be a nongenomic fast regulation of GC through the membrane-GR, which perhaps affected the calcium channel.