Privileged access to mitochondria of calcium influx through N-methyl-D-aspartate receptors.
Privileged access to mitochondria of calcium influx through N-methyl-D-aspartate receptors.
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发表时间：
1998-06
影响因子：
3.6
通讯作者：
T. Peng;J. Greenamyre
中科院分区：
文献类型：
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作者：
T. Peng;J. Greenamyre
线粒体Ca ~（2+）摄取对胞浆Ca ~（2+）水平的变化动态敏感地响应，并在隔离由N-甲基-D-天冬氨酸（NMDA）受体激活诱导的大Ca ~（2+）负荷中起关键作用。然而，NMDA受体激活，胞质Ca 2+增加，和线粒体Ca 2+摄取之间的精确的相互关系仍然不清楚。为了可靠地、独立地、同时地检测同一细胞中胞浆和线粒体Ca 2+浓度的变化，我们用两种Ca 2+指示剂钙绿色1 N和rhod-2装载原代纹状体神经元，并用激光扫描共聚焦荧光显微镜观察单个神经元的荧光信号。在动力学数据分析中，仅使用来自预定义胞质区域的钙绿色信号和来自预定义线粒体区域的rhod-2信号，并且注意力集中在响应的初始快速上升阶段。当用100 μ M NMDA处理神经元时，胞质和线粒体Ca 2+的增加显示出相似的时间过程和变化率，并且似乎是时间锁定的。相比之下，当神经元用100 μ M红藻氨酸盐、50 mM KCl或0.3 μ M离子霉素处理时，线粒体Ca 2+的增加滞后于胞质Ca 2+的增加。这些数据表明，响应于胞质Ca 2+的增加的线粒体Ca 2+摄取在NMDA受体激活期间比在非NMDA受体或电压依赖性Ca 2+通道激活期间更快且更紧密地偶联。这种熟练的线粒体Ca 2+摄取可能避免了响应于NMDA受体激活的胞浆Ca 2+浓度的大幅上升。然而，它可能导致线粒体内过量的Ca 2+积累，并使线粒体对Ca 2+介导的损伤敏感。
Mitochondrial Ca2+ uptake responds dynamically and sensitively to changes in cytosolic Ca2+ levels and plays a crucial role in sequestering the large Ca2+ load induced by N-methyl-D-aspartate (NMDA) receptor activation. However, the precise interrelationships between NMDA receptor activation, cytosolic Ca2+ increase, and mitochondrial Ca2+ uptake remain obscure. To reliably, independently, and simultaneously detect cytosolic and mitochondrial Ca2+ concentration changes in the same cell, we loaded primary striatal neurons with two Ca2+ indicators, calcium green 1N and rhod-2, and visualized the fluorescence signals from single neurons with laser scanning confocal fluorescence microscopy. In kinetic data analysis, only calcium green signals from predefined cytosolic areas and rhod-2 signals from predefined mitochondrial regions were used, and attention was focused on the initial rapid rising phase of the responses. When neurons were treated with 100 microM NMDA, increases of cytosolic and mitochondrial Ca2+ showed similar time courses and rates of change, and seemed to be time-locked. In contrast, when neurons were treated with 100 microM kainate, 50 mM KCl, or 0.3 microM ionomycin, mitochondrial Ca2+ increases lagged behind cytosolic Ca2+ increases. These data suggest that mitochondrial Ca2+ uptake in response to an increase of cytosolic Ca2+ is faster and more tightly coupled during NMDA receptor activation than during non-NMDA receptor or voltage-dependent Ca2+ channel activation. This proficient mitochondrial Ca2+ uptake may avert a large rise in cytosolic Ca2+ concentration in response to NMDA receptor activation. Yet, it may lead to excessive Ca2+ accumulation inside mitochondria and render mitochondria susceptible to Ca2+ mediated injury.