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 。
A series of experiments on Nd3+ influx mediated by the Na+/Ca2+ exchange in human lymphocytes were processed by fura-2 method. The results show that when the cellular Na+ gradient is reversed, Nd3+ can enter the lymphocytes and voltage dependent calcium channels are not responsible for Nd3+ influx. It suggests that the Na+ / Ca2+ exchange provides a major route for NP entry in human lymphocytes. Intracellular free Nd3+ concentrations ([Nd3+ ](i)) are directly proportional to extracellular free Nd3+ concentrations ([Nd3+ ](i)) and the maximum [Nd3+](i) is (3.67 +/- 0.32) X 10(-14) mol . L-1 . [Nd3+ ](i) decreases with decreasing extracellular pH but increases with decreasing intracellular [ Ca2+](i) The Ca2+ influx and Nd3+ influx mediated by the Na+/Ca2+ exchange might be mutually competitive. Furthermore, the results also suggest that cytosolic Nd3+ is transported by the ATP-dependent Ca2+ pump and intracellular Nd3+ appears to be taken up by endoplasmic reticulum and not be significantly accumulated by niitochondria.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2003年第2期256-261,共6页
Acta Chimica Sinica
基金
国家自然科学基金重大项目 (No.2 9871 0 2 0 )资助
