De Giorgi F, Lartigue L, Ichas F
European Institute of Chemistry and Biology, & INSERM EMI-U.9929 Mitochondrial Physiology, Victor Segalen-Bordeaux 2 University, Bordeaux cedex, F-33076, France.
Cell Calcium. 2000 Nov-Dec;28(5-6):365-70. doi: 10.1054/ceca.2000.0177.
Kinetic fluorescence imaging and the potentiometric probe tetramethylrhodamine methyl ester (TMRM) were used to evoke and detect changes in membrane potential (delta Psi(m)) of individual mitochondria in living cells. As a combined effect of preferential TMRM accumulation in mitochondria, and of TMRM photoactivation, individual organelles displayed sharp transient depolarizations caused by local reactive oxygen species (ROS)-mediated gatings of the mitochondrial permeability transition pore (PTP). In COS-7 cells, such directed repetitive gatings of the PTP gave rise to stochastic delta Psi(m)flickering at the level of individual organelles, but also to prominent synchronous delta Psi(m)transitions in whole subgroups of the mitochondrial population, indicative of the existence of an underlying electrically coupled mitochondrial network. In single cells, this network could comprise as much as 65% of the total mitochondrial population, a nd exhibited a high plasticity with mitochondrial units spontaneously connecting to and disconnecting from the coupled structure within seconds. These results indicate that in resting cells, the mitochondrial network is a dynamic proton-conducting structure capable to commute and coordinate electrical signals generated by the PTP.
利用动力学荧光成像和电位探针四甲基罗丹明甲酯（TMRM）来激发和检测活细胞中单个线粒体的膜电位（ΔΨm）变化。由于TMRM优先在线粒体中积累以及TMRM光激活的综合作用，单个细胞器会出现由局部活性氧（ROS）介导的线粒体通透性转换孔（PTP）门控引起的急剧瞬时去极化。在COS - 7细胞中，PTP的这种定向重复门控不仅在单个细胞器水平上引起随机的ΔΨm闪烁，还在整个线粒体群体的亚组中引起明显的同步ΔΨm转变，这表明存在潜在的电耦合线粒体网络。在单细胞中，该网络可占线粒体总数的65%之多，并表现出高度的可塑性，线粒体单元能在数秒内自发地与耦合结构连接或断开连接。这些结果表明，在静息细胞中，线粒体网络是一种动态的质子传导结构，能够传递和协调由PTP产生的电信号。
