Fig. 3
Fast, slow and asynchronous release during trains, in control and in LatB. a Average release rate (per ms and per simple synapse; 3 mM external [Ca2+] and 200 Hz stimulation; n = 11 experiments). Middle panel: Expanded vertical scale highlighting asynchronous release. Lower panel: Scaled latency distributions for stimuli 1, 3, 5 and 7 are superimposed to show a marked latency broadening during trains. b Effect of LatB on cumulative latency counts during trains. Overall latency counts (upper row) have been decomposed into a superslow component representing asynchronous release (middle row) and a phasic component (lower row). Black: Control synapses (3 mM external [Ca2+] and 200 Hz stimulation). Red: Synapses pretreated with LatB to inhibit actin-dependent SV movement. c Superimposed cumulative latency distributions for each AP stimulation during an 8-AP train, both for control data (left) and in LatB (right). Average traces of 8-AP responses (thick black curve) is fitted with a double exponential (red) with indicated τfast and τslow values. d Full model with reversible transition between recycling pool and replacement site (forward: Sf, backward: Sb). e Relative contributions of τfast and τslow component as a function of stimulus number (symbols and continuous lines: experimental; dashed lines: simulations)
