Voltage-operated calcium channels neurons

When the action potential reaches the synaptic bouton, depolarisation triggers the opening of voltage-operated calcium channels in the membrane (Figure 2.5). The concentration gradient for Ca2+ favours the passive movement of this ion into the neuron. The subsequent rise in cytoplasmic Ca2+ ion concentration stimulates the release of neurotransmitter into the synaptic cleft, which diffuses across this narrow gap and binds to receptors located on the postsynaptic neuronal membrane (Figure 2.5). 

B rtolino. M. etal (1992) The central role of voltage-activated and receptor-operated calcium channels in neuronal cells. i4nnu. Rev. Phannacol. Toxicol., 32. 399-421. 

---