【摘要】 利用Fura 2荧光浓度指示剂法对Na+ Ca2 + 交换介导的Nd3+ 跨人外周血淋巴细胞膜行为进行了一系列研究 .结果表明 :当细胞形成向外的Na+ 梯度时Nd3+ 能跨膜进入细胞 ,电压依赖性L 型Ca2 + 通道对Nd3+ 进入无贡献 ,提出了Na+ Ca2 +交换系统是Nd3+ 进入细胞的主要途径 ;在安全浓度范围内进入胞内的游离Nd3+ 浓度与胞外的Nd3+ 浓度成正比 ,计算表明进入胞内的最大游离Nd3+ 浓度为 ( 3 67± 0 32 )× 10 - 1 4 mol·L- 1 ;当胞外pH值降低时进入胞内的游离Nd3+ 浓度减小 ,胞内游离Ca2 + 浓度减小时进入的游离Nd3+ 浓度略微增大 ,胞外Nd3+ 和Ca2 + 竞争Na+ Ca2 + 交换位点 ;结果进一步推测进入胞内的Nd3+ 可被质膜钙泵泵出胞外 ,初步实验表明进入胞浆中的Nd3+ 会在内质网中进一步累积 ,而在线粒体中不累积更多还原

【Abstract】 A series of experiments on Nd 3+ influx mediated by the Na +/Ca 2+ exchange in human lymphocytes were processed by fura-2 method. The results show that when the cellular Na + gradient is reversed, Nd 3+ can enter the lymphocytes and voltage dependent calcium channels are not responsible for Nd 3+ influx. It suggests that the Na +/Ca 2+ exchange provides a major route for Nd 3+ entry in human lymphocytes. Intracellular free Nd 3+ concentrations ( i) are directly proportional to extracellular free Nd 3+ concentrations ( o) and the maximum i is (3.67±0.32)×10 -14 mol·L -1. i decreases with decreasing extracellular pH but increases with decreasing intracellular i. The Ca 2+ influx and Nd 3+ influx mediated by the Na +/Ca 2+ exchange might be mutually competitive. Furthermore, the results also suggest that cytosolic Nd 3+ is transported by the ATP-dependent Ca 2+ pump and intracellular Nd 3+ appears to be taken up by endoplasmic reticulum and not be significantly accumulated by mitochondria.更多还原