Quantal release of transmitter is not associated with channel opening on the neuronal membrane.
The traditional view that quantal release of neurotransmitter results from the fusion of transmitter-containing vesicles with the neuronal membrane has been recently challenged. Although various alternative mechanisms have been proposed, a common element among them is the release of cytoplasmic transmitter, which, in one view, could occur through large conductance channels on the presynaptic membrane. Six nerve-muscle cell pairs were examined with a whole-cell patch clamp for the presence of such channels that are associated with the production of miniature end-plate potentials. Examination of the neuronal membrane current during the occurrence of 822 miniature end-plate potentials produced no evidence of large channels. Thus it is unlikely that quantal release is mediated by such channels in the neuromuscular junction.
D000818:Animals; D002462:Cell Membrane / Q000502:physiology*; D002478:Cells, Cultured; D008564:Membrane Potentials; D009045:Motor Endplate / Q000166:cytology / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D014981:Xenopus
D018377:Neurotransmitter Agents