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Repolarization of the presynaptic action potential and short‐term synaptic plasticity in the chick ciliary ganglion
Author(s) -
Poage Robert E.,
Zengel Janet E.
Publication year - 2002
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.10135
Subject(s) - ciliary ganglion , neural facilitation , neuroscience , synaptic plasticity , long term potentiation , biology , stimulation , repolarization , neurotransmission , ganglion , electrophysiology , excitatory postsynaptic potential , inhibitory postsynaptic potential , receptor , biochemistry
Abstract Stimulation‐induced increases in synaptic efficacy have been described as being composed of multiple independent processes that arise from the activation of distinct mechanisms at the presynaptic terminal. In the chick ciliary ganglion, four components of short‐term synaptic plasticity have been described: F 1 and F 2 components of facilitation, augmentation, and potentiation. In the present study, intracellular recording from the presynaptic calyciform nerve terminal of the chick ciliary ganglion revealed that the late repolarization and afterhypolarization (AHP) phases of the presynaptic action potential are affected by repetitive stimulation and that the time course of these effects parallel that of facilitation. The effects of these changes in the presynaptic action potential time course on calcium influx were tested by using the recorded action potential waveforms as voltage command stimuli during whole‐cell patch‐clamp recordings from acutely isolated chick ciliary ganglion neurons. The “facilitated” action potential waveform (slowed repolarization, decreased AHP amplitude) evoked calcium current with slightly but significantly greater total calcium influx. Taken together, these results are consistent with the hypothesis that activity‐dependent changes in the presynaptic action potential are one of several mechanisms contributing to the facilitation phase of stimulation‐induced increases in transmitter release in this preparation. Synapse 46:189–198, 2002. © 2002 Wiley‐Liss, Inc.