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 [Ca²⁺]_i and potential of cell membrane in HepG₂ tumor cells．Methods Staining with Fluo一3／AM，[Ca²⁺]_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 [Ca²⁺]_i in HepG₂ tumor cells increased while the potential of cell membrane in HepG₂ tumor cells decreased．The elevate intension of [Ca²⁺]_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(P2+]_i in HepG₂ tumor cells，there was a big increase at 48 h after betaine treatment，but a 1ess 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 [Ca²⁺]_i in HepG₂ tumor cells， which could induce the apoptosis．

国家自然科学基金资助项目(30400352);教育部重点项目(205045);黑龙江省自然科学基金资助项目(D200611);黑龙江省研究生创新基金资助项目(YJSCX2006-0077HSD)