外源性神经节苷脂对人－肝癌培养细胞内钙的作用及其方式

本工作采用荧光探针Ｆｕｒａ－２ＡＭ观察了外源性神经节苷脂ＧＭ３和ＧＤ３对ＳＭＭＣ－７７２１人肝癌培养细胞钙的影响，证明ＧＭ３和ＧＤ３均能升高细胞内钙浓度（［Ｃａ２＋］ｉ），但程度上有极大差异。１０ｎｍｏｌ／ｍＬＧＭ３或１．０ｎｍｏｌ／ｍＬＧＤ３可使［Ｃａ２＋］ｉ上升高是明显，与对照相比［Ｃａ２＋］ｉ分别增加２１５～２５０％和４２％。进一步用Ｖｅｒａｐａｍｉｌ阻断钙通道和内质网钙释放、去除细胞外Ｎａ＋以抑制Ｎａ＋－Ｃａ２＋交换以及去除细胞外Ｃａ２＋在无外钙内流等系统观察了ＧＭ３和ＧＤ３的作用方式，结果提示ＧＭ３升高［Ｃａ２＋］ｉ的机制是一个同时增加内质网钙释放、激活钙通道并伴有质膜Ｃａ２＋－ＡＴＰ酶激活的综合结果；而ＧＤ３则主要抑制Ｎａ＋－Ｃａ２＋交换系统。

The Mode of Action of Exogenous Gangliosides on Cytosolic Calcium of Cultured Human Hepatoma Cells

Effects of exogenous GM3 or GD3 on cytosolic free calcium(Ca2 ]1) in the SMMC-7721 cultured human hepatoma cells were monitored by the fluorescence probe fura-2 and the results Proved that both GM3 and CD3 could stimulate a rapid tranaient increase of Ca2 ]1 with quite differrent levels.Ca2 ]1 could be elavated to the higheds level by a dose of 10 nmol/ml GM3 or 1 nmol/ml GD3 with the increasing rate up to 215-250% and 42% respectively as compared with the control. Further studies on the mode of action of GM3 and GD3 were carried out in differently treated systems,such as by using verapamil,the inhibitor of caleium channel in plasma membrane and calcium-releasing system of endoplasmic recticu recticum(ER); or removing Na from the culture media to inhibit Na -Ca2 exchanger;or remoting Ca2 from the culture media to block the enter of extracellular Ca2 .The results demonstrated that the mechanism of elevating Ca2 ]1 by GM3was through activating calcium channel,releasing Ca2 from ER rapidly and stimulatingthe Ca2 -ATPase on the plasma membranes; that by GD3 was through inhibiting Na -Ca2 exchanger mainly.