Calcium mobilization from mitochondria in synaptic transmitter release

Abstract

Mitochondria can rapidly accumulate and release Ca2+ upon cell stimulation. A paper by Yang and coworkers in this issue reports an unusual form of synaptic potentiation, dependent on Ca2+ release from mitochondria through the Na+/Ca2+ exchanger and triggered by Na+ entry through voltage-gated channels (Yang et al., 2003).

Figure 1.

Schematic outline of the proposed role for mitochondria (Mt) in synaptic release at the neuromuscular junction. Na⁺ influx through voltage gated Na⁺ channels (green) increases Na⁺ concentration in the presynaptic terminal, in turn triggering mitochondrial Ca²⁺ release through the mitochondrial Na⁺/Ca²⁺ exchanger (yellow). Ca²⁺ release triggers the fusion of presynaptic vesicles with the plasma membrane and the release of neurotransmitter. The released neurotransmitter binds to and opens acetylcholine receptors (blue) on the postsynaptic terminal.