Calcium-independent synaptic transmission: artifact or fact?
The release of neurotransmitters at classical chemical synapses occurs via Ca2+ influx through voltage-dependent Ca2+ channels, which are opened following depolarization of presynaptic terminals. However, owing to a persistence or increase in the amount of transmitter released in preparations containing low concentrations of Ca2+, it has been proposed that transmitter release could also occur through a Ca(2+)-independent, carrier-mediated process. On the other hand, lowering extracellular [Ca2+] can actually promote Ca2+ influx through voltage-activated Ca2+ channels via a modification of the surface potential of plasma membranes. Therefore, the proposed Ca(2+)-independent transmitter release could be re-accommodated within the framework of the Ca2+ hypothesis of synaptic transmission by taking into account the surface-charge effects.
Piccolino
M
M
Dipartimento di Biologia, Università di Ferrara, Italy.
Pignatelli
A
A
D016477:Artifacts; D002118:Calcium / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D002118:Calcium