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Cell Calcium. 2005 May;37(5):489-95.

Presynaptic Ca2+ dynamics, Ca2+ buffers and synaptic efficacy.

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  • 1Department of Experimental Neurophysiology, Faculty of Earth and Life Sciences, CNCR, Vrije Universiteit Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.


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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