ABSTRACT
A spontaneous neurotransmitter release at the frog neuromuscular junction in the absence of an action potential in the presynaptic motor neuron was first observed by Fatt and Katz. This chapter considers how electrical and biochemical events in the presynaptic terminal lead to secretion of neurotransmitters. Classical studies at the neuromuscular junction demonstrated that an action potential conducted to the presynaptic terminal, within 1 ms, triggers release of the neurotransmitter acetylcholine into the synaptic cleft with activation of the postsynaptic receptors. The site of neurotransmitter release, where synaptic vesicle exocytosis occurs, was termed the “active zone” in 1970 by R Couteaux and M Pecot-Dechavassine. They analyzed the ultrastructure of nerve terminals at the neuromuscular junction of a frog by electron microscopy. In the active zone, quantum release of neurotransmitter occurs following the fusion of individual synaptic vesicles with the plasma membrane, a process termed “exocytosis.”.
