Figure 5.

Quantal parameters of synchronous release and the releasable vesicle pool size are not affected in AP-3 KO animals. A) Averaged eEPSCs recorded during stimulation trains (10 Hz, 10 stimuli) in ACSF containing 4mM [Ca²⁺]. B) Peak amplitudes of the 1^st and 10^th eEPSCs in a train are plotted against repetition number and fitted with linear fit, solid black (WT) and red (KO) lines in order to exclude the involvement of long-term plastic changes. C) Pooled variance-mean plots, parabolic fits are shown as dashed lines (WT -black, n = 13 and KO - red, n = 15). D) Comparison of calculated quantal size Q in WTs, n=13 and KOs, n=15). E) Number of release sites (N) and initial release probability (p) calculated from parabolic fits (WT n=12, KO n=13). Data for individual cells are shown as black squares (WT) and red circles (KO). None of the parameters are significantly different. F) eEPSCs amplitude during stimulation train (50 Hz, 3000 stimuli), black and response to the same stimulation 10 seconds later, red. Note a smaller amplitude of the response to the second train. Inset shows expanded response at the end of the train after vesicle depletion. Corresponding cumulative amplitudes are shown on G. Dashed lines represent back extrapolated linear fits obtained from last 1000 stimuli (solid red). WT data are shown. H and I) Comparison of the number of vesicles per release site (Nq, WT n=8, KO n=6), size of ready releasable pool of vesicles (RRP), percentage and speed of RRP recovery after 10 seconds (WT n=9, KO n=6). The data for individual cells are shown as black squares (WT) and red circles (KO). Error bars show standard error of the mean (SEM).