Mitochondria exert a negative feedback on the propagation of intracellular Ca2+ waves in rat cortical astrocytes.
Mitochondria exert a negative feedback on the propagation of intracellular Ca2+ waves in rat cortical astrocytes.
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DOI：
10.1083/jcb.145.4.795
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发表时间：
1999-05-17
期刊：
影响因子：
--
通讯作者：
Duchen MR
中科院分区：
文献类型：
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作者：
Boitier E;Rea R;Duchen MR
我们使用数字荧光成像技术来探索大鼠皮质星形胶质细胞中线粒体Ca2+摄取和生理Ca2+信号传导之间的相互作用。细胞质内Ca2+ ([Ca2+]cyt)的增加是由于ER Ca2+储存的动员引起的，随后是线粒体Ca2+ （[Ca2+]m，使用rhod-2监测）的增加。而[Ca2+]细胞在~ 1分钟内恢复，[Ca2+]m的恢复时间为~ 30分钟。分散线粒体膜电位（Δψm，使用线粒体解耦剂羰基氰化物对三氟甲氧基苯基腙[FCCP]和寡霉素）阻止线粒体Ca2+摄取并减缓[Ca2+]细胞瞬态衰变的速度，这表明线粒体Ca2+摄取在星形胶质细胞中清除生理[Ca2+]细胞负荷中起着重要作用。这些细胞中的Ca2+信号由受体介导的ER Ca2+释放或机械刺激引发，通常由传播波组成（使用fluo-3测量）。在两种刺激下，波的平均传播速度为22.9±11.2 μm/s （n = 262）。随后是线粒体去极化波（使用四甲基罗丹明乙酯[TMRE]测量），与Ca2+波穿过细胞时进入线粒体的Ca2+摄取一致。Δψm的崩溃，以防止线粒体Ca2+摄取显著增加50%的Ca2+波的传播速率。综上所述，这些数据表明，线粒体的细胞质Ca2+缓冲提供了一种有效的机制来调节星形细胞Ca2+信号的局部传播。
We have used digital fluorescence imaging techniques to explore the interplay between mitochondrial Ca2+ uptake and physiological Ca2+ signaling in rat cortical astrocytes. A rise in cytosolic Ca2+ ([Ca2+]cyt), resulting from mobilization of ER Ca2+ stores was followed by a rise in mitochondrial Ca2+ ([Ca2+]m, monitored using rhod-2). Whereas [Ca2+]cyt recovered within ∼1 min, the time to recovery for [Ca2+]m was ∼30 min. Dissipating the mitochondrial membrane potential (Δψm, using the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxy-phenyl-hydrazone [FCCP] with oligomycin) prevented mitochondrial Ca2+ uptake and slowed the rate of decay of [Ca2+]cyt transients, suggesting that mitochondrial Ca2+ uptake plays a significant role in the clearance of physiological [Ca2+]cyt loads in astrocytes. Ca2+ signals in these cells initiated either by receptor-mediated ER Ca2+ release or mechanical stimulation often consisted of propagating waves (measured using fluo-3). In response to either stimulus, the wave traveled at a mean speed of 22.9 ± 11.2 μm/s (n = 262). This was followed by a wave of mitochondrial depolarization (measured using tetramethylrhodamine ethyl ester [TMRE]), consistent with Ca2+ uptake into mitochondria as the Ca2+ wave traveled across the cell. Collapse of Δψm to prevent mitochondrial Ca2+ uptake significantly increased the rate of propagation of the Ca2+ waves by 50%. Taken together, these data suggest that cytosolic Ca2+ buffering by mitochondria provides a potent mechanism to regulate the localized spread of astrocytic Ca2+ signals.