  Zinc, a suspected potentiator of learning and memory, is shown to affect
exocytotic release and storage in neurotransmitter-containing vesicles.
Structural and size analysis of the vesicular dense core and halo using
transmission electron microscopy was combined with single-cell amperometry to
study the vesicle size changes induced after zinc treatment and to compare
these changes to theoretical predictions based on the concept of partial
release as opposed to full quantal release. This powerful combined analytical
approach establishes the existence of an unsuspected strong link between
vesicle structure and exocytotic dynamics which can be used to explain the
mechanism of regulation of synaptic plasticity by Zn 2+ through modulation of
neurotransmitter release.
