氨对脑细胞胞浆游离钙含量的影响

目的与方法：采用Ｆｕｒａ－２／ＡＭ探针技术观察ＮＨ４Ｃｌ对离体急性分离之Ｗｉｓｔａｒ乳鼠大脑细胞胞头游离钙「Ｃａ＾２＋」ｉ含量的影响。结果：ＮＨ４＾＋浓度为２．５ｍｍｏｌ／Ｌ时脑细胞内「Ｃａ＾２＋」ｉ含量升高。在一定范围内，随着ＮＨ４＾＋浓度的加大，细胞内Ｃａ＾２＋持续升高。ＮＨ４＾＋的升钙作用主要被Ｎｉｃａｒｄｉｐｉｎｅ所阴断，其变化特征类以ＫＣｌ。结论：ＮＨ４＾＋主要通过影响电压依赖性钙离子通

THE EFFECT OF AMMONIA ON THE FREE CALCIUM CONTENT OF ISOLATED BRAIN CELLS

Aim and methods: The effect of ammonium chloride on the free calcium{[Ca 2 ] i} content of isolated brain cell from newborn Wistar rats(25 d) were investigated by Fura2/AM probe techniques in SHIMADZU RF5000 SpectrofIuorophotometer (Japan).Results: The [Ca 2 ] i, content in 2.5 mmol/L of ammoniumtreated cells was increased. The cytoplasmic [Ca 2 ] i content raised continuously following the increase of ammonium concentration. The effect of NH 4 could be blocked by Nicardipine, a kind of blocker for voltagegated calcium channel, which was similar to that ot KCI.Conclusion: NH 4 might result in the calcium homeostasis imbalance of brain cells through interfering the voltagegated calcium channels. Variable dysfunction,metabolic alteration and structural abnormality in ammonia intoxication happened in acute or chronic hepatic dieases might be related to the intracelluar calcium homeostasis imbalance caused by hyperammonemia.