Spontaneous Calcium Oscillation and Mitochondrial Traffic in Cortical Neurons

Mitochondria are dynamic organelles in cells. The control of mitochondrial motility by signaling mechanisms and the significance of rapid changes in motility remains elusive. Simultaneous confocal imaging of mitochondrial movement and intracellular calcium was performed on cortical neurons loaded with both Mitotracker and fluo‐4. We observed extensive movement of mitochondria in both directions along neuronal processes. Mitochondrial movement occurred in a saltatory pattern, with rapid movement between fixed points interrupted by delays. Mitochondrial movement was not clear affected by transient increases in [Ca2+] associated with action potential firing. Neither synchronous Ca2+ oscillations induced by bicuculline nor high‐frequency Ca2+ transients evoked by forskolin modified mitochondrial traffic. Only sustained increases in [Ca2+]i evoked by glutamate decreased the velocity of mitochondrial movement. Mitochondrial movement continued during and after exposure to CNQX, MK801, TTX, thapsigargin, ryanodine, and 0 Ca2+ medium. In summary only large and sustained increases in intracellular Ca2+ concentration evoked by 10 uM glutamate were associated with a small but significant decrease in the velocity of mitochondrial movement. Support Contributed By: NIDA DA 05010