In the two time series in Fig. 9, the process is both schematically depicted (Fig. 9B–E), and visualized by showing the fluorescence intensity of co-internalized fluorescent contents (Fig. 9F–I). Upon fluid injection at a constant flow rate, the newly formed vesicle grows with simultaneous shortening of the nanotube. Eventually, vesicle opening occurs spontaneously, mimicking the final stage of exocytosis. After release of the contents of a vesicle in this SC 79 system, a new vesicle is formed with the attached nanotube so release can be reproducibly repeated. This approach allows both visualization and, electroanalytical quantification of released material, in mole case the redox-active catechol. Highly quantitative and temporal measurements have been carried out with amperometry using a carbon fiber electrode set up as shown in Fig. 9A [8], [9] and [10]. These measurements have been used to argue that membrane mechanics is sufficient to account for the temporal aspects of the final vesicle opening in exocytosis. It is evident that lipid flow might be important in regulating release via the fusion pore and that exocytotic flow might be important in regulating the response during synaptic release.
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