Transport of magnesium by two isoforms of the Na+-Ca2+ exchanger expressed in CCL39 fibroblasts
Transport of magnesium by two isoforms of the Na+-Ca2+ exchanger expressed in CCL39 fibroblasts
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DOI：
10.1007/s004240000384
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发表时间：
2000-10-01
影响因子：
4.5
通讯作者：
Kurihara, S
中科院分区：
文献类型：
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作者：
Tashiro, M;Konishi, M;Kurihara, S
在CCL 39细胞中，用荧光指示剂测量细胞质中Ca 2+（[Ca 2 +]（i））和Mg 2+（[Mg 2 +]（i））的浓度，CCL 39细胞是从中国仓鼠肺成纤维细胞建立的细胞系，用从犬心脏（NCX 1）或大鼠脑（NCX 3）分离的Na+-Ca 2+交换器的互补脱氧核糖核酸（cDNA）转染。将细胞外[Mg 2 +]升高至10 mM增加了Mg 2+内流，并且在无Ca 2+条件下用furaptra监测[Mg 2 +]（i）（Delta [M2+]（i））的所得变化。对照（载体转染的）细胞，45分钟时的Delta [Mg 2 +]（i）与有或无细胞外Na+相似（130 mM或0 mM），当[Na+]（i）被1 mM哇巴因处理提高时，NCX 1转染细胞中的δ [Mg 2 +]（i）为：在130 mM Na+存在下显着减弱，但在去除细胞外Na+或用mM哇巴因处理时，变得与对照细胞中的相当（或略大于对照细胞）。表达NCX 3的细胞显示Delta [Mg 2 +]（i）对Na+的中等依赖性，这可能反映了交换蛋白的表达程度较低。[Ca 2 +]（i）的细胞外Na+依赖性变化（在细胞外Ca 2+和10 μ M离子霉素（一种Ca 2+离子载体）存在下用fura-2测量）在对照细胞中最小，在NCX 1转染的细胞中显著，在NCX 3转染的细胞中居中。这些结果表明，Na+-Ca 2+交换器（NCX 1或NCX 3）可以运输Mg 2+，并可能在镁从细胞中挤出的作用。
Cytoplasmic concentrations of Ca2+ ([Ca2+](i)) and Mg2+ ([Mg2+](i)) were measured with fluorescent indicators in CCL39 cells, a cell line established from Chinese hamster lung fibroblasts, transfected with complementary deoxyribonucleic acid (cDNA) of the Na+-Ca2+ exchanger isolated either from canine heart (NCX1) or from rat brain (NCX3). Raising extracellular [Mg2+] to 10 mM increased Mg2+ influx and the resultant change in [Mg2+](i) (Delta [M2+](i)) was monitored with furaptra under Ca2+-free conditions. In control (vector-transfected) cells, Delta [Mg2+](i) at 45 min was similar with or without extracellular Na+ (130 mM or 0 mM) and when [Na+](i) was raised by 1 mM ouabain treatment, Delta [Mg2+](i) in NCX1-transfected cells was;attenuated significantly in the presence of 130 mM Na+, but became comparable to (or slightly larger than) that in control cells on either removal of extracellular Na+ or treatment with mM ouabain. Cells expressing NCX3 showed an intermediate dependence of Delta [Mg2+](i) on Na+, probably reflecting a lower degree of expression of the exchanger protein. Extracellular Na+-dependent changes in [Ca2+](i) (measured with fura-2 in the presence of extracellular Ca2+ and 10 muM ionomycin, a Ca2+ ionophore) were minimal in control cells, marked in the NCX1-transfected cells and intermediate in the NCX3-transfected cells. These results suggest that the Na+-Ca2+ exchanger (either NCX1 or NCX3) can transport Mg2+ and may play a role in the extrusion of magnesium from cells.