A reevaluation of the role of mitochondria in neuronal Ca2+ homeostasis
A reevaluation of the role of mitochondria in neuronal Ca2+ homeostasis
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DOI：
10.1046/j.1471-4159.1996.66010403.x
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发表时间：
1996-01-01
影响因子：
4.7
通讯作者：
Nicholls, DG
中科院分区：
文献类型：
--
作者：
Budd, SL;Nicholls, DG
重新检查了线粒体Ca 2+转运限制神经元内游离胞质Ca 2+浓度升高的能力，通过数字Fura-2成像监测培养的小脑颗粒细胞。KCl去极化后，除了质子载体羰基氰间氯苯腙（CCCP）去极化线粒体释放到胞体和神经突的细胞质中的钙池。在非去极化细胞中没有发现CCCP释放池。虽然KCl诱发的体细胞和轴突Ca 2+浓度升高时，CCCP是在KCl去极化增强，这是与崩溃的ATP/ADP比。在ATP合成酶抑制剂寡霉素的存在下，糖酵解保持高ATP/ADP比率至少10分钟。进一步添加的线粒体复合物I抑制剂鱼藤酮导致线粒体膜电位的崩溃，监测罗丹明-123，但对ATP/ADP比率没有影响。在鱼藤酮/寡霉素的存在下，没有CCCP释放池被发现后，KCl去极化，与取消线粒体Ca 2+转运一致，然而，矛盾的是，KCl诱发的Ca 2+升高降低。可以得出结论，CCCP诱导的细胞质Ca 2+响应KCl的增加是由于抑制非线粒体ATP依赖的运输和线粒体Ca 2+运输增强Ca 2+的进入，可能是通过去除负责电压激活的Ca 2+通道活性的反馈抑制的细胞质位点的阳离子。
The ability of mitochondrial Ca2+ transport to limit the elevation in free cytoplasmic Ca2+ concentration in neurones following an imposed Ca2+ load is reexamined, Cultured cerebellar granule cells were monitored by digital fura-2 imaging. Following KCl depolarization, addition of the protonophore carbonylcyanide m-chlorophenylhydrazone (CCCP) to depolarize mitochondria released a pool of Ca2+ into the cytoplasm in both somata and neurites. No CCCP-releasable pool was found in nondepolarized cells. Although the KCl-evoked somatic and neurite Ca2+ concentration elevations were enhanced when CCCP was present during KCl depolarization, this was associated with a collapsed ATP/ADP ratio. In the presence of the ATP synthase inhibitor oligomycin, glycolysis maintained high ATP/ADP ratios for at least 10 min. The further addition of the mitochondrial complex I inhibitor rotenone led to a collapse of the mitochondrial membrane potential, monitored by rhodamine-123, but had no effect on ATP/ADP ratios. In the presence of rotenone/oligomycin, no CCCP-releasable pool was found subsequent to KCl depolarization, consistent with the abolition of mitochondrial Ca2+ transport; however, paradoxically the KCl-evoked Ca2+ elevation is decreased. It is concluded that the CCCP-induced increase in cytoplasmic Ca2+ response to KCl is due to inhibition of nonmitochondrial ATP-dependent transport and that mitochondrial Ca2+ transport enhances entry of Ca2+ perhaps by removing the cation from cytoplasmic sites responsible for feedback inhibition of voltage-activated Ca2+ channel activity.