Inhibition of SLMV exocytosis by clostridial neurotoxins.

<p>A. Time-course of cocktail-induced (glucose 20 mM; KCl 30 mM; forskolin 10 µM, IBMX 100 µM) pHluorin fluorescence intensity obtained with TIRF illumination in cell transfected with a control plasmid or with tetanus neurotoxin-tomato (TeTX). The curve represents the whole-cell pHluorin fluorescence signal, expressed as ΔF/F₀ obtained averaging results from 3 and 9 cells, respectively. B. The same as A. but in cells transfected with a control plasmid or with GFP-botulinum neurotoxin C (BoNT/C). Since the GFP-tagged BoNT/C light chain is uniformly distributed in the cytoplasm, the fluorescence signal originating from this construct in the TIRFM evanescent field was negligible. The curve represents the whole-cell pHluorin fluorescence signal, expressed as ΔF/F₀ obtained averaging results from 5 and 6 cells, respectively. C–D. Histograms represent the amplitudes ΔF/F₀) of the cocktail-induced pHluorin fluorescence intensity change in cells transfected with control plasmids or with TeTX or BoNT/C.