Presynaptic Ca2+ dynamics, Ca2+ buffers and synaptic efficacy
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Updated: Aug 7, 2026

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Published on: January 5, 2010
1Department of Experimental Neurophysiology, Faculty of Earth and Life Sciences, CNCR, Vrije Universiteit Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands. nail@bio.vu.nl
Abstract:
In synapses neurotransmitter release is triggered by elevation of Ca2+ concentration at a Ca2+ sensor of the release machinery. The Ca2+ concentration at the release site at the given time point is determined by Ca2+ dynamics within presynaptic terminal. It depends on a source of Ca2+ (usually voltage-gated Ca2+ channels), diffusional distance between the source of Ca2+ and the Ca2+ sensor and Ca2+ buffering by endogenous Ca2+ buffers. In many synapses transmitter release can be enhanced (facilitated) during repetitive activity of neurons. The main source of facilitation is activity-dependent increase of Ca2+ concentration at the release site. Several mechanisms of facilitation have been proposed, namely, accumulation of residual Ca2+, multi-site (X receptor) mechanism and partial Ca2+ buffer saturation mechanism. In this review we discuss theoretical and experimental evidence in favor of one or the other of proposed mechanisms.
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