甜菜碱对HepG_2人肝癌细胞[Ca^(2+)]_i和细胞膜电位的影响

Effects of betaine on [Ca^(2+)]_i and potential of cell membrane in HepG_2 tumor cells

目的研究甜菜碱对肝癌HepG2细胞内游离Ca2+浓度([Ca2+]i)和细胞膜电位的影响。方法Fluo-3/AM标记,激光扫描共聚焦显微镜观察HepG2细胞[Ca2+]i,TMRE标记,激光扫描共聚焦显微镜测定细胞膜电位的影响。结果甜菜碱能够升高HepG2细胞[Ca2+]i,降低细胞膜电位。升高[Ca2+]i的强度具一定的剂量依赖性,随甜菜碱剂量的增大而升高。甜菜碱50、25mg/mL组与对照组比较差异非常显著(P<0.01),甜菜碱12.5mg/mL组与对照组比较差异显著(P<0.05)。给药48h时间段内细胞内的[Ca2+]i升高的幅度较大,72h升高幅度相对较小。而降低膜电位上,在48h时间段内,甜菜碱50、25、12.5mg/mL各组膜电位均显著高于对照组(P<0.05),但在72h时间段内甜菜碱12.5mg/mL组与对照组比较没有显著性差异(P>0.05)。结论甜菜碱通过开放细胞膜上的通透性转换孔道(MPTP),从而升高HepG2细胞[Ca2+]i,启动细胞凋亡机制,诱导HepG2细胞凋亡。

Objective To study the effects of betaine on [Ca^2＋]i and potential of cell membrane in HepG2 tumor cells. Methods Staining with Fluo-3/AM, [Ca^2＋]i in HepG2 tumor cells was observed by laser scanning confocal microscope, staining with TMRE, membrane potential in HepG2 tumor cells was observed by laser scanning confocal microscope. Results After treating with betaine, the [Ca^2＋ ]i in HepG2 tumor cells increased while the potential of cell membrane in HepG2 tumor cells decreased. The elevate intension of [Ca^2＋ ]i from the divided three groups was in a dose-dependent manner, it will elevate if the betaine dose increases. Compared with the control group, the betaine groups of 50 and 25 mg/mL had the extraordinary significant effect （P〈0.01）, of 12.5 mg/mL （P〈0.05）. For the [Ca^2＋]i in HepG2 tumor cells, there was a big increase at 48 h after betaine treatment, but a less increase at 72 h after betaine treatment. For the potential of cell membrane in HepG2 tumor cells, the betaine groups of 50, 25, and 12.5 mg/mL had the significant effect （P〈0.05） at 48 h after betaine treatment, but the group of 12.5 mg/mL had no notable effect （P〉0.05） at 72 h after betaine treatment. Conclusion Betaine opens the mitochondrium permeability transition pore （MPTP） to increase the [Ca^2＋]i in HepG2 tumor cells, which could induce the apoptosis.