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Nature. 1998 Jul 23;394(6691):384-8.

High-frequency firing helps replenish the readily releasable pool of synaptic vesicles.

Author information

1
Division of Neurology & The Program in Brain and Behavior, The Hospital for Sick Children, Department of Physiology, University of Toronto, Ontario, Canada.

Abstract

Synapses in the central nervous system undergo various short- and long-term changes in their strength, but it is often difficult to distinguish whether presynaptic or postsynaptic mechanisms are responsible for these changes. Using patch-clamp recording from giant synapses in the mouse auditory brainstem, we show here that short-term synaptic depression can be largely attributed to rapid depletion of a readily releasable pool of vesicles. Replenishment of this pool is highly dependent on the recent history of synaptic activity. High-frequency stimulation of presynaptic terminals significantly enhances the rate of replenishment. Broadening the presynaptic action potential with the potassium-channel blocker tetraethylammonium, which increases Ca2+ entry, further enhances the rate of replenishment. As this increase can be suppressed by the Ca2+-channel blocker Cd2+ or by the Ca2+ buffer EGTA, we conclude that Ca2+ influx through voltage-gated Ca2+ channels is the key signal that dynamically regulates the refilling of the releasable pool of synaptic vesicles in response to different patterns of inputs.

PMID:
9690475
DOI:
10.1038/28645
[Indexed for MEDLINE]

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