稀土元素La、Gd和Ce对培养大鼠细胞生物学效应的研究

目的 在细胞水平上研究稀土元素（REE）La,Gd和Ce对培养大鼠细胞的生物学作用及机。方法 采用同位素示踪、质子激发X荧光分析（PIXE）结合生化及细胞学等技术观察La对细胞的生物学作用，La,Gd及Ce的亚细胞分布及Gd,Ce对细胞钙含量及钙内流的影响。结果 La^3 在10^－10（或10^-9)-10^-6mol/L时促进细胞蛋白质合成、线粒体琥珀酸脱氢酶活性增加、DNA合成以及S期细胞比率增加，但La^2 在高剂量时（10^-4-10^-3mol/L)降低平滑肌细胞总蛋白质含量、抑制线粒体琥珀酸脱氢酶酸活性以及S期细胞比率减少。通过PIXE发现La,Gd,Ce可进入细胞，且在核内含量最高，其次为胞膜。Gd和Ce使细胞内钙含量增加，促进细胞钙内流。结论（1）La^3 对细胞有明显剂量－效应关系，在10^-10(或10^-19)-10^-6mol/L剂量范围内有促进细胞增殖作用。在10^-4-10^-3mol/L时有细胞毒性作用。（2）REE可进入细胞，且在核内富集。（3）REE可促进细胞外钙进入细胞。

A study of the biological effects of rare earth elements at cellular level using nuclear techniques

Objective　To investigate the biological effects and the effecting mechanisms of rare earth elements La，Gd and Ce on cultured rat cells.Methods　The biological effects of La3+ on cultured rat cells and the subcellular distribution of La and Gd and Ce, and the inflow of 45Ca2+ into the cells and total cellular calcium were measured by isotopic tracing, Proton Induced X Ray Emission Analysis (PIXE) and the techniques of biochemistry and cellular biology.Results　La3+ at the concentration of 10-10(or 10-9)～10-6mol/L significantly increased quantity of incorporation of 3H-TdR into DNA, total cellular protein and the activity of succinic dehydrogenase of mitochondria. The cell cycle analysis showed that the proportions of cells in S phase were accordingly increased acted by La3+ at above range of concentration. But these values were significantly decreased when concentration of La3+ raised to 10-4～10-3mol/L. It was further discovered that La，Gd，and Ce distributed mostly in the nuclei, and then in membranes. Gd and Ce also promoted the inflow of 45Ca2+ into the cells and increased the total calcium content in cells.Conclusions　① La3+ at a wide concentration range of 10-10( or 10-9)～10-6mol/L promotes proliferation of cultured rat cells, but at even higher concentration (10-4～10-3mol/L) shows cellular toxicity, and there is a striking dose-effect relationship. ② La，Gd and Ce can enter the cells and mainly distribute in the nuclei. ③ Gd and Ce can promote the inflow of extracellular Ca2+ into the cells and increase total cellular calcium.