Additive stimulatory effect of extracellular calcium and potassium on non-transferrin ferric iron uptake by HeLa and K562 cells
Additive stimulatory effect of extracellular calcium and potassium on non-transferrin ferric iron uptake by HeLa and K562 cells
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DOI：
10.1016/s0005-2736(01)00367-4
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发表时间：
2001-09-03
影响因子：
3.4
通讯作者：
Kovár, J
中科院分区：
文献类型：
--
作者：
Musílková, J;Kovár, J
我们研究了Ca~(2+)和K~+对HeLa和K562细胞从柠檬酸铁络合物摄取非转铁蛋白铁的影响。在Na-HEPES缓冲液(137 mM NaC l，4 mM KCI)中的摄取实验表明，细胞外Ca~(2+)对铁摄取有刺激作用。加入4 mM Ca~(2+)的铁摄取率约为无Ca~(2+)时的3~5倍。在高K+水平的K-HEPES缓冲液(68 mM NaC l，75 mM KCI)中，铁摄取在前10分钟被一过性刺激。K-HEPES缓冲液对0.4 mM Ca~(2+)的铁吸收速率约为Na-HEPES缓冲液中的3倍。钙通道阻滞剂。维拉帕米(50um)和硝苯地平(5um)对对照Na-HEPES缓冲液和K+刺激K-HEPES缓冲液的摄取均无影响。钠通道阻滞剂利多卡因(50 MU)对Na-HEPES缓冲液和K+刺激后的铁摄取也无影响。此外，用等渗蔗糖取代Na-HEPES和K-HEPES缓冲液中的Na对铁的吸收没有显著影响。我们的结论是，细胞外钙本身，而不是细胞内钙或钙离子转运，刺激了HeLa和K562细胞对铁离子的摄取。高水平的胞外K+也刺激摄取，可能是通过细胞膜去极化。Na+不参与这些铁摄取的刺激。瞬时K+效应和持续性钙离子效应似乎是相加的。(C)2001 Elsevier Science B.V.保留所有权利。
We studied the effects of Ca2+ and K+ on non-transferrin iron uptake from ferric citrate complex by HeLa and K562 cells. Uptake experiments in Na-HEPES buffer (137 mM NaCl, 4 mM KCI) showed that extracellular Ca2+ stimulated the iron uptake. The rate of iron uptake in 4 mM Ca2+ was about 3-5 times higher than without Ca2+. The iron uptake in K-HEPES buffer (68 mM NaCl, 75 mM KCI) with a high K+ level was transiently stimulated during the first 10 min. The rate of iron uptake for 0.4 mM Ca2+ was approximately 3 times higher in K-HEPES buffer than in Na-HEPES buffer. The calcium channel blockers. verapamil (50 muM) and nifedipine (5 muM) had no effect on the uptake either in control Na-HEPES buffer or after K+ stimulation in K-HEPES buffer. The sodium channel blocker lidocaine (50 muM) also had no effect on the uptake of iron in Na-HEPES buffer as well as after K+ stimulation. Furthermore, the iron uptake was not significantly affected when Na in the Na-HEPES and K-HEPES buffers was replaced by isotonic saccharose. We conclude that extracellular calcium per se, and not intracellular calcium or Ca2+ transport, stimulates ferric iron uptake by both HeLa and K562 cells. A high level of extracellular K+ also stimulates the uptake, probably via cell membrane depolarization. Na+ is not involved in these stimulations of iron uptake. The transient K+ effect and continuous Ca2+ effect seem to be additive. (C) 2001 Elsevier Science B.V. All rights reserved.