Sodium-calcium exchange in aortic myocytes and renal epithelial cells. Dependence on metabolic energy and intracellular sodium.
Sodium-calcium exchange in aortic myocytes and renal epithelial cells. Dependence on metabolic energy and intracellular sodium.
复制标题
主动脉肌细胞和肾上皮细胞中的钠钙交换。
DOI：
10.1111/j.1749-6632.1991.tb17344.x
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发表时间：
1991
影响因子：
5.2
通讯作者：
Smith,L
中科院分区：
文献类型：
--
作者：
Smith,JB;Lyu,RM;Smith,L
某些哺乳动物细胞的质膜含有一种称为Na+-Ca 2+交换器的蛋白质，可以将Na+和Ca 2+以相反的方向转运。尽管这种交换剂在二十多年前就被发现了，但由于缺乏特异性抑制剂，它对Ca ~（2+）调节的作用一直难以确定。培养的哺乳动物细胞非常适合于评估个别转运蛋白对激素和其他外部刺激的整体Ca 2+调节的具体贡献。通过确定刺激对游离Ca 2+和总Ca 2+以及45 Ca 2+通量的影响，可以获得比由单一方法提供的更可靠的Ca 2+调节图片。为了评估Na+-Ca 2+交换对细胞CaZ+调节的贡献，有必要确定操纵细胞内和细胞外Na+浓度的影响。然而，细胞外Na+的急剧减少可能会触发三磷酸肌醇的产生和储存的Ca 2+的释放，这取决于特定的细胞类型和哺乳动物物种。外部Ca 2+和Mg 2+增强Ca 2+动员响应外部Na+的突然减少。4因此，实验方法的组合对于区分由CaZ+通过Na+-Ca 2+交换器流入引起的胞质游离Ca 2+（[Caz+] i）的变化和由触发Na+敏感性受体引起的储存Caz+释放引起的[Ca 2 +] i变化是必不可少的。对Ca ~（2+）调节的研究表明，在某些动脉肌细胞和肾上皮细胞中存在丰富的Na ~+-Ca ~（2+）交换。动脉肌细胞和肾上皮细胞中的交换器具有与心肌细胞中的交换器非常相似的几个动力学特征。
The plasma membrane of certain mammalian cells contains a protein called the Na+-Ca2+ exchanger that translocates Na+ and Ca2+ in opposite directions. Although the exchanger was discovered more than twenty years ago,'S2 its contribution to Ca2+ regulation has been difficult to determine because of the lack of a specific inhibitor. Cultured mammalian cells are well suited to assessing the specific contribution of individual transporters to overall Ca2+ regulation by hormones and other external stimuli. By determining the effects of a stimulus on free and total Caz+ as well as 45Ca2+ fluxes, a more reliable picture of Ca2+ regulation may be obtained than would be provided by a single approach. To assess the contribution of Na+-Ca2+ exchange to cellular CaZ+ regulation, it is necessary to determine the effects of manipulating intraand extracellular Na+ concentration. An acute decrease in extracellular Na+, however, may trigger the production of inositol trisphosphate and the release of stored Ca2+, depending on the particular cell type and mammalian specie^.^ External Ca2+ and Mgz+ potentiate the Ca2+-mobilizing response to an abrupt decrease in external Na+. 4 Therefore, a combination of experimental approaches is essential for distinguishing changes in cytosolic free Ca2+([Caz+] J that are caused by CaZ+ influx via the Na+-Ca2+ exchanger from the [Ca2+ Ii changes due to release of stored Caz+ evoked by triggering the Na+-sensitive receptor. Comprehensive studies of Ca2+ regulation indicate that Na+-Ca2+ exchange is plentiful in certain arterial myocytes and renal epithelial cells. The exchanger in arterial myocytes and renal epithelial cells has several kinetic features that are quite similar to those in cardiac myocytes.