As tri-n-butyltin (TBT), one of the environmental pollutants, is accumulated in wild animals, concern regarding the toxicity of TBT in both wildlife and human is increasing. TBT has been reported to increase intracellular Ca(2+) concentration in several types of cells. In order to examine how Ca(2+) is involved in TBT-induced cell death, the effect of TBT on rat thymocytes has been compared with that of A23187, a calcium ionophore, under various concentrations of external Ca(2+) using a flow cytometer and fluorescent probes. Although both TBT and A23187 were toxic to cells under normal Ca(2+) condition, under external Ca(2+)-free condition the cytotoxic action of TBT was potentiated without changing the threshold concentration while that of A23187 was completely abolished. A23187 attenuated the TBT-induced descent in cell viability under normal Ca(2+) concentration despite intracellular Ca(2+) concentration was increased. As external Ca(2+) concentration increased, the TBT-induced increase in number of dead cells gradually decreased whereas the number of cells in an early stage of apoptosis increased. Results suggest that Ca(2+) has contradictory actions on the process of TBT-induced cell death in rat thymocytes.

中文翻译：

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A23187和CaCl（2）对三正丁基锡诱导的大鼠胸腺细胞死亡的影响。

随着三正丁基锡（TBT）（一种环境污染物）在野生动物中积累，人们越来越关注三丁基锡在野生生物和人类中的毒性。据报道，TBT可以增加几种类型细胞的细胞内Ca（2+）浓度。为了检查Ca（2+）如何参与TBT诱导的细胞死亡，在各种浓度的外部Ca（2+）的作用下，已将TBT对大鼠胸腺细胞的作用与钙离子载体A23187的作用进行了比较。流式细胞仪和荧光探针。尽管TBT和A23187在正常Ca（2+）条件下均对细胞有毒性，但在无外部Ca（2+）条件下，TBT的细胞毒性作用得到增强，而未改变阈值浓度，而A23187的阈值浓度则被完全废除。尽管增加了细胞内Ca（2+）的浓度，A23187在正常Ca（2+）浓度下减弱了TBT诱导的细胞活力下降。随着外部Ca（2+）浓度增加，TBT诱导的死细胞数量增加逐渐减少，而凋亡早期阶段的细胞数量增加。结果表明，Ca（2+）在TBT诱导的大鼠胸腺细胞死亡过程中具有矛盾的作用。