Oyama Toshihisa B, Oyama Keisuke, Kawanai Takuya, Oyama Tomohiro M, Hashimoto Erika, Satoh Masaya, Oyama Yasuo
Laboratory of Cellular Signaling, Faculty of Integrated Arts and Sciences, The University of Tokushima, Tokushima 770-8502, Japan.
Toxicology. 2009 Aug 21;262(3):245-9. doi: 10.1016/j.tox.2009.06.016. Epub 2009 Jun 25.
Effect of tri-n-butyltin (TBT), an environmental pollutant, on intracellular Zn(2+) concentration was tested in rat thymocytes to reveal one of cytotoxic profiles of TBT at nanomolar concentrations using a flow cytometer and appropriate fluorescent probes. TBT at concentrations of 30 nM or more (up to 300 nM) significantly increased the intensity of FluoZin-3 fluorescence, an indicator for intracellular Zn(2+) concentration, under external Ca(2+)- and Zn(2+)-free condition. Chelating intracellular Zn(2+) completely attenuated the TBT-induced augmentation of FluoZin-3 fluorescence. Result suggests that nanomolar TBT releases Zn(2+) from intracellular store site. Oxidative stress induced by hydrogen peroxide also increased the FluoZin-3 fluorescence intensity. The effects of TBT and hydrogen peroxide on the fluorescence were additive. TBT-induced changes in the fluorescence of FluoZin-3 and 5-chloromethylfluorescein, an indicator for cellular thiol content, were correlated with a coefficient of -0.962. Result suggests that the intracellular Zn(2+) release by TBT is associated with TBT-induced reduction of cellular thiol content. However, chelating intracellular Zn(2+) potentiated the cytotoxicity of TBT. Therefore, the TBT-induced increase in intracellular Zn(2+) concentration may be a type of stress responses to protect the cells.
环境污染物三丁基锡（TBT）对大鼠胸腺细胞内锌离子（Zn(2+)）浓度的影响进行了测试，以使用流式细胞仪和合适的荧光探针揭示纳摩尔浓度下TBT的细胞毒性特征之一。在无外部钙离子（Ca(2+)）和锌离子（Zn(2+)）的条件下，浓度为30 nM或更高（最高300 nM）的TBT显著增加了FluoZin-3荧光强度，这是细胞内锌离子（Zn(2+)）浓度的指标。螯合细胞内锌离子（Zn(2+)）完全减弱了TBT诱导的FluoZin-3荧光增强。结果表明，纳摩尔浓度的TBT从细胞内储存位点释放锌离子（Zn(2+)）。过氧化氢诱导的氧化应激也增加了FluoZin-3荧光强度。TBT和过氧化氢对荧光的影响是相加的。TBT诱导的FluoZin-3和5-氯甲基荧光素（细胞内硫醇含量的指标）荧光变化的相关系数为-0.962。结果表明，TBT引起的细胞内锌离子（Zn(2+)）释放与TBT诱导的细胞内硫醇含量降低有关。然而，螯合细胞内锌离子（Zn(2+)）增强了TBT的细胞毒性。因此，TBT诱导的细胞内锌离子（Zn(2+)）浓度增加可能是一种保护细胞的应激反应类型。
