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 La 3+ on cultured rat cells and the subcellular distribution of La and Gd and Ce, and the inflow of 45Ca 2+ 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 La 3+ 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 La 3+ at above range of concentration. But these values were significantly decreased when concentration of La 3+ 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 45Ca 2+ into the cells and increased the total calcium content in cells.Conclusions ① La 3+ 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 Ca 2+ into the cells and increase total cellular calcium.
P. Zhao, Xiangrui Ji, Hua Zhang
Chinese Journal of Nuclear Mdeicine