Mechanisms and regulation of Mg2+ efflux and Mg2+ influx.
Mechanisms and regulation of Mg2+ efflux and Mg2+ influx.
复制标题
镁流出和流入的机制和调节。
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
T. Günther
中科院分区：
文献类型：
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作者：
T. Günther
当细胞内游离Mg 2+（[Mg 2 +]i）浓度增加时，人、鸡和大鼠红细胞、大鼠胸腺细胞和HL 60细胞发生Mg 2+净流出，并持续到达到原始细胞Mg 2+含量，表明增加[Mg 2 +]i可诱导和调节Mg 2+净流出。通过电中性Na+/Mg 2+反向转运进行净Mg 2+流出，由细胞外/细胞内Na+梯度驱动。Na+/Mg 2+反向转运是不可逆的，仅进行净Mg 2+流出。Na+/Mg ~（2+）逆向转运被阿米洛利、奎尼丁和丙咪嗪抑制。除[Mg ~（2+）]i增加外，胸腺细胞Na ~+/Mg ~（2+）逆向转运还受cAMP的调节，cAMP可诱导Na ~+/Mg ~（2+）逆向转运的最大速率。当细胞Mg 2+含量实验性降低时发生净Mg 2+内流，并且当在合适的培养基中重新孵育后达到原始细胞Mg 2+含量时停止，表明通过[Mg 2 +]i经由反馈抑制进行调节。游离肝细胞内Mg ~（2+）的净内流依赖于细胞外Mg ~（2+）、Na ~+、Cl ~-、HCO ~（3-）和Pi。Mg ~（2+）的净内流可能是通过电中性Na ~+、Mg ~（2+）/阴离子共转运来进行的，这种共转运是由细胞内外Na ~+梯度驱动的。然而，不能排除由细胞外Na+和阴离子门控的产电Mg 2+内流。cAMP可刺激Mg ~（2+）内流，阿米洛利和维拉帕米可抑制Mg ~（2+）内流。净Mg 2+流出和净Mg 2+流入是独立和受调节的途径，建立细胞内Mg 2+的稳态。
Net Mg2+ efflux occurred in human, chicken and rat erythrocytes, rat thymocytes and HL60 cells when the concentration of intracellular free Mg2+ ([Mg2+]i) was experimentally increased and proceeded until the original cellular Mg2+ content was reached, indicating induction and regulation of net Mg2+ efflux by increased [Mg2+]i. Net Mg2+ efflux was performed by electroneutral Na+/Mg2+ antiport, driven by the extra-/intracellular Na+ gradient. Na+/Mg2+ antiport was irreversible, performing only net Mg2+ efflux. Na+/Mg2+ antiport was inhibited by amiloride, quinidine and imipramine. Besides increased [Mg2+]i, Na+/Mg2+ antiport in thymocytes was regulated by cAMP which induced a maximal rate of Na+/Mg2+ antiport. Net Mg2+ influx occurred when the cellular Mg2+ content was experimentally reduced and stopped when after reincubation in suitable media the original cellular Mg2+ content was reached, indicating regulation by [Mg2+]i via feedback inhibition. Net Mg2+ influx in isolated hepatocytes was dependent on extracellular Mg2+, Na+, Cl-, HCO3- and Pi. Net Mg2+ influx may operate via electroneutral Na+, Mg2+/anion cotransport, driven by the extra-/intracellular Na+ gradient. However, electrogenic Mg2+ influx gated by extracellular Na+ and anions cannot be excluded. Net Mg2+ influx was stimulated by cAMP and inhibited by amiloride and verapamil. Net Mg2+ efflux and net Mg2+ influx are separate and regulated pathways, establishing homeostasis of intracellular Mg2+.