Spatially organised mitochondrial calcium uptake through a novel pathway in chick neurones.

A brief depolarisation of chick sensory neurones evokes a calcium increase in mitochondria that peaks 1-2s after the depolarisation event and then decays over tens of seconds. Peripheral mitochondria take up more calcium than do central ones, even when the cytosolic calcium increase is spatially homogeneous. The calcium influx into mitochondria does not occur by the Ruthenium Red-sensitive mitochondrial calcium uniporter, and persists when the mitochondrial membrane voltage is dissipated by protonophore. These results indicate that a novel pathway, distinct from the more familiar mitochondrial calcium uniporter, allows brief electrical activity to effect significant increases of mitochondrial calcium that will in turn modulate mitochondrial energy production.