Ca2+-dependent mechanisms of presynaptic control at central synapses.
Classically, a high-power association relates the neurotransmitter release probability to the concentration of presynaptic Ca2+. Activated by the action potential waveform, voltage-gated Ca2+ channels mediate Ca2+entry into presynaptic terminals. Inside the terminal, Ca2+ ions rapidly bind to endogenous intracellular buffers and could trigger Ca2+ release from internal Ca2+ stores. The resulting space-time profile of free Ca2+ determines the time course and probability of neurotransmitter release through the interaction with molecular release triggers strategically located in the vicinity of release sites. Following a rapid concentration transient, excess Ca2+ has to be removed from the cytosol through the process involving Ca2+ uptake by the endoplasmatic reticulum stores, sequestration by mitochondria, and/or extrusion into the extracellular medium. The ongoing synaptic activity could affect any of the multiple factors that shape presynaptic Ca2+ dynamics, thus arbitrating use-dependent modification of the neurotransmitter release probability. Here we present an overview of major players involved in Ca2+-dependent presynaptic regulation of neurotransmitter release and discuss the relationships arising between their actions.
Rusakov
Dmitri A
DA
Institute of Neurology, University College London, London, UK. d.rusakov@ion.ucl.ac.uk
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D002490:Central Nervous System / Q000502:physiology*; D006801:Humans; D018377:Neurotransmitter Agents / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013569:Synapses / Q000378:metabolism*
D015220:Calcium Channels; D018377:Neurotransmitter Agents; D002118:Calcium