GM_3、GD_3作用下SMMC－7721肝癌细胞内磷脂酰肌醇（1，4，5）三

外源性ＧＭ３（１０ｎｍｏｌ／ｍＬ）、ＧＤ３（１ｎｍｏｌ／ｍＬ）可使ＳＭＭＣ－７７２１人肝癌培养细胞内钙浓度呈快速的短暂升高，其到达峰值时间为４５秒，一次作用后，内钙水平于２－３ｍｉｎ内恢复至对照水平。在一定时间间隔中连续几次加入ＧＭ３或ＧＤ３后内钙水平的变化表明，ＧＭ３所引起的［Ｃａ２＋］ｉ的增加依赖于内质网钙贮的释放和细胞外钙的流入；而ＧＤ３增加［Ｃａ２＋］ｉ与此二系统无关。进一步研究表明，在细胞内钙达峰值时，１０ｎｍｏｌ／ｍＬＧＭ３可使ＩＰ３（１，４，５）浓度增加９．３倍，ｃＡＭＰ浓度增加８２％；１ｎｍｏｌ／ｍＬＧＤ３反使Ｉｐ３浓度增加１．２倍，提示ＧＭ３、ＧＤ３升高内钙的不同机制。

A Primary Report on The Changes of lnositol-1 , 4 , 5-Triphosphate and cAMP of SMMC-7721 Cultured Human Hepatoma Cells by GM_3 and GD_3

The results on the research of SMMC-7721 cultured human hepatoma cells showed that both 10nmol/mL of exogenous GM3 and 1nmol/mL of exogenous GD3 could stimulate a transient rapid increase of Ca2 ]i, and it took 45sec to reach the maximum value of Ca2 ]i.After one addition of GM3 or GD3 ,Ca2 ]i would recover to control level within 2-3 minutes. Treatments with interval addition of GM3 or GD3 in different situation, the increase of Ca2 ]i in duced by GM3 depended on the releasing of Ca2 from ER and influxing of Ca2 ; on the other hand, by GD3 showed no relationship with these two systems. Further studies demonstrated that when Ca2 ]i reached maximum level , the concentration of IP3 (1 , 4 , 5) was increased 9. 3 folds and cAMP, 82%, as compared with control. By the treatment of 1nmol GD3 , IP3 (1 , 4, 5) was only raised slightly (82%). These results might suggest that there are different mechanisms of increasing Ca2 ]i between GM3 and GD3.