Spontaneous Na+ transients in individual mitochondria of intact astrocytes
Spontaneous Na+ transients in individual mitochondria of intact astrocytes
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DOI：
10.1002/glia.20619
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发表时间：
2008-02-01
期刊：
影响因子：
6.2
通讯作者：
Chatton, Jean-Yves
中科院分区：
文献类型：
--
作者：
Azarias, Guillaume;Van de Ville, Dimitri;Chatton, Jean-Yves
尽管大的电化学梯度有利于阳离子流入基质，但完整细胞中的线粒体仍保持较低的 Na+ 水平。此外，它们还表现出个体自发的瞬时去极化。我们在此报告，使用线粒体探针 CoroNa Red 测量，活体星形胶质细胞中的单个线粒体表现出 Na+ 浓度自发增加（Na-mit(+) 尖峰）。在包含 30 个星形胶质细胞的视野中，在静息条件下通常会检测到每分钟高达 1,400 次瞬变。在神经元中也观察到 Na-mit(+) 尖峰，但在测试的两种非神经细胞类型中很少见。星形细胞 Na-mit(+) 峰值平均持续时间为 12.2 +/- 0.8 s，幅度为 35.5 +/- 3.2 mM，并且与短暂的线粒体去极化同时发生；它们受到线粒体去极化和钌红的损害，表明阳离子单向转运蛋白的参与。 Na-mit(+) 尖峰活性受到线粒体 Na+/H+ 交换抑制的显着抑制，并且对细胞 pH 和 Na+ 浓度敏感。 Ca2+ 对 Na-mit(+) 尖峰活动起许可作用。最后，我们提供的证据表明 Na-mit(+) 尖峰频率与细胞 ATP 水平相关。这项研究表明，在生理条件下，活星形胶质细胞中的单个线粒体表现出跨内膜的快速 Na+ 交换，这揭示了一种高度动态和局部功能调节的新形式。 (C) 2007 Wiley-Liss, Inc.
Mitochondria in intact cells maintain low Na+ levels despite the large electrochemical gradient favoring cation influx into the matrix. In addition, they display individual spontaneous transient depolarizations. We report here that individual mitochondria in living astrocytes exhibit spontaneous increases in their Na+ concentration (Na-mit(+) spiking), as measured using the mitochondrial probe CoroNa Red. In a field of view with similar to 30 astrocytes, up to 1,400 transients per minute were typically detected under resting conditions. Na-mit(+) spiking was also observed in neurons, but was scarce in two nonneural cell types tested. Astrocytic Na-mit(+) spikes averaged 12.2 +/- 0.8 s in duration and 35.5 +/- 3.2 mM in amplitude and coincided with brief mitochondrial depolarizations; they were impaired by mitochondrial depolarization and ruthenium red pointing to the involvement of a cation uniporter. Na-mit(+) spiking activity was significantly inhibited by mitochondrial Na+/H+ exchanger inhibition and sensitive to cellular pH and Na+ concentration. Ca2+ played a permissive role on Na-mit(+) spiking activity. Finally, we present evidence suggesting that Na-mit(+) spiking frequency was correlated with cellular ATP levels. This study shows that, under physiological conditions, individual mitochondria in living astrocytes exhibit fast Na+ exchange across their inner membrane, which reveals a new form of highly dynamic and localized functional regulation. (C) 2007 Wiley-Liss, Inc.