Cytoplasmic Na+-dependent modulation of mitochondrial Ca2+ via electrogenic mitochondrial Na+-Ca2+ exchange
Cytoplasmic Na+-dependent modulation of mitochondrial Ca2+ via electrogenic mitochondrial Na+-Ca2+ exchange
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DOI：
10.1113/jphysiol.2007.148726
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发表时间：
2008-03-15
影响因子：
5.5
通讯作者：
Matsuoka, Satoshi
中科院分区：
文献类型：
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作者：
Kim, Bongju;Matsuoka, Satoshi
为了阐明线粒体 Na+-Ca2+ 交换 (NCXmito) 在完整和去极化线粒体膜电位 (Delta Psi(mito)) 下调节线粒体 Ca2+ (Ca-mito(2+)) 浓度的作用，我们分别使用荧光探针 Rhod-2 和 TMRE 在透化的大鼠心室细胞中测量 Ca-mito(2+) 和 Delta Psi(mito)。应用 300 nM 细胞质 Ca2+ (Ca-c(2+)) 会增加 Ca-mito(2+)，并且这种增加会被细胞质 Na+ (Na-c(+)) 减弱，IC50 为 2.4 mM。相反，当Delta Psi(mito)被线粒体解偶联剂FCCP去极化时，Na-c(+)增强了Ca-c(2+)诱导的Ca-mito(2+)增加，EC50约为4 mM。这种增加不受钌红或环孢素 A 的显着影响。当 Delta Psi(mito) 完整时，CGP-37157 对 NCXmito 的抑制进一步增加了 Ca-mito(2+)，而当 Delta Psi(mito) 去极化时，它抑制了 Ca-mito(2+) 的增加，表明 Delta Psi(mito) 去极化将交换模式从正向改变为反向。此外，Delta Psi(mito) 去极化通过正向模式显着减少了 Ca-mito(2+) 的减少，并通过反向模式增强了 Ca-mito(2+) 的增加。当呼吸链减弱时，NCXmito反向模式的诱导使Delta Psi(mito)超极化，而NCXmito正向模式诱导时Delta Psi(mito)去极化。 CGP-37157 显着抑制了 Delta Psi(mito) 的两种变化。上述实验数据表明NCXmito具有电压依赖性和产电性。这一概念得到了计算机模拟研究的理论上支持，该模型基于当前和以前的研究构建了 NCXmito 模型，假设连续的生电 Na+-Ca2+ 交换和去极化引起的 Na+ 通量增加。结论是Na-c(+)和Delta Psi(mito)通过生电NCXmito动态调节Ca-mito(2+)浓度。
To clarify the role of mitochondrial Na+-Ca2+ exchange (NCXmito) in regulating mitochondrial Ca2+ (Ca-mito(2+)) concentration at intact and depolarized mitochondrial membrane potential (Delta Psi(mito)), we measured Ca-mito(2+) and Delta Psi(mito) using fluorescence probes Rhod-2 and TMRE, respectively, in the permeabilized rat ventricular cells. Applying 300 nM cytoplasmic Ca2+ (Ca-c(2+)) increased Ca-mito(2+) and this increase was attenuated by cytoplasmic Na+ (Na-c(+)) with an IC50 of 2.4 mM. To the contrary, when Delta Psi(mito) was depolarized by FCCP, a mitochondrial uncoupler, Na-c(+) enhanced the Ca-c(2+)-induced increase in Ca-mito(2+) with an EC50 of about 4 mM. This increase was not significantly affected by ruthenium red or cyclosporin A. The inhibition of NCXmito by CGP-37157 further increased Ca-mito(2+) when Delta Psi(mito) was intact, while it suppressed the Ca-mito(2+) increase when Delta Psi(mito) was depolarized, suggesting that Delta Psi(mito) depolarization changed the exchange mode from forward to reverse. Furthermore, Delta Psi(mito) depolarization significantly reduced the Ca-mito(2+) decrease via forward mode, and augmented the Ca-mito(2+) increase via reverse mode. When the respiratory chain was attenuated, the induction of the reverse mode of NCXmito hyperpolarized Delta Psi(mito), while Delta Psi(mito) depolarized upon inducing the forward mode of NCXmito. Both changes in Delta Psi(mito) were remarkably inhibited by CGP-37157. The above experimental data indicated that NCXmito is voltage dependent and electrogenic. This notion was supported theoretically by computer simulation studies with an NCXmito model constructed based on present and previous studies, presuming a consecutive and electrogenic Na+-Ca2+ exchange and a depolarization-induced increase in Na+ flux. It is concluded that Ca-mito(2+) concentration is dynamically modulated by Na-c(+) and Delta Psi(mito) via electrogenic NCXmito.