SPONTANEOUS CHANGES IN MITOCHONDRIAL MEMBRANE POTENTIAL

神经退行性疾病，如帕金森氏症，是美国人口中最紧迫的健康问题之一，并且与中枢神经系统中过量的谷氨酸活动有关。谷氨酸，作用于NMDA受体复合物，允许Ca2+流入细胞。当[Ca2+]c升高时，线粒体开始隔离Ca2+。抑制这一线粒体过程可显著提高细胞存活率。这些数据暗示了线粒体在神经退行性细胞死亡中的作用，并建议进一步探索线粒体的生理和功能。本文将探讨健康培养神经元线粒体膜电位（deltapsim）自发变化的性质和意义。负载了deltapsim敏感荧光染料的神经元在神经元过程的小区域表现出自发的荧光强度振荡。虽然已知许多细胞和线粒体活动会影响deltapsim，但我们的主要假设是deltapsim振荡反映了线粒体对细胞内[Ca2+]或能量需求变化的补偿机制，并可能通过渗透性过渡孔的短暂打开来完成。此外，已知线粒体功能障碍在导致坏死和凋亡的级联事件中起关键作用，但它们是否参与这些死亡途径的初始阶段仍未解决。以deltapsim振荡为标记，观察坏死或凋亡刺激后的线粒体功能。这些实验将作为全面评估线粒体参与神经退行性细胞死亡的基础。

Neurodegenerative diseases, such as Parkinson's, are among the most pressing health concerns in the American population and have been linked to excessive glutamatergic activity in the central nervous system. Glutamate, acting at the NMDA receptor complex, allows the influx of Ca2+ into the cell. As [Ca2+]c rises, mitochondria begin to sequester Ca2+. Inhibiting this mitochondrial process significantly improves cell survival. These data implicate mitochondria in neurodegenerative cell death and suggest that mitochondrial physiology and function should be further explored. In the resent proposal, the nature and significance of spontaneous changes in mitochondrial membrane potential (deltapsim) in healthy cultured neurons will be examined. Neurons loaded with deltapsim sensitive fluorescent dyes exhibit spontaneous oscillations in fluorescent intensity in small regions of the neuronal processes. Although numerous cellular and mitochondrial activities are known to influence deltapsim, our primary hypothesis is that deltapsim oscillations reflect compensatory mechanisms of mitochondria to changes in intracellular [Ca2+] or in energy demands and may be accomplished by transient openings of the permeability transition pore. Moreover, mitochondrial dysfunction is known to be critically involved in cascades of events that lead to necrosis and apoptosis, however whether they participate in the initial stages of these death pathways remains unresolved. Using deltapsim oscillations as a marker, mitochondrial function after necrotic r apoptotic stimuli will be followed. These experiments will act as a foundation for the complete assessment of mitochondrial involvement in neurodegenerative cell death.