Fig. 3. Exocytosis of ANF-EGFP-containing DCVs in neuronal soma and neurites. (A) Comparison of release probabilities for vesicles in soma and neurites. In the soma, about one third of the plasma-membrane-proximal vesicles underwent exocytosis in 100 seconds, whereas less than 1% in the neurites could release. A total of 1091 vesicles were analyzed in soma and 1344 vesicles in neurites (^***P<0.001). (B) Depolarization-evoked DCV events exhibit long latencies. Events in the soma and neurites were binned in 10-second intervals and plotted by percentage. Soma events were fitted with a single exponential curve (broken line) to calculate a time constant, (15.6 seconds). Neurite events did not fit a single exponential curve but were evident at long times. (C) Single exocytosis events in neuronal soma. (Ci) A representative example of DCV exocytosis in the soma. The time interval between two consecutive points was 0.1 seconds. The time between the fluorescence baseline and the fluorescence peak (fluorescence rise time) was designated as t_r. Release of content was calculated based on the fluorescence change (F) between 2 seconds before and 15 seconds after exocytosis. (Cii) A DCV in the soma underwent two consecutive exocytic events. Shown below the curves are images of the corresponding DCV at a time interval of 0.2 seconds. Start points of the events are indicated by arrows. Scale bars: 500 nm. (D) A representative example of DCV exocytosis in the neurites. The time interval between two consecutive points was 0.2 seconds. Shown below the curve are images of the corresponding DCV at a time interval of 0.2 seconds. The start point of the exocytic event is indicated by an arrow. Scale bar: 500 nm. (E) Analysis of the content released during exocytosis for DCVs in soma and neurites. Content release was determined as the loss of fluorescence (F) by subtraction of the value 2 seconds before an event from that obtained 15 seconds after the event. Gaussian fitting revealed two populations of events in the soma (solid lines) and one population in the neurites (broken line). (F) Comparison of the fluorescence rise time (t_r) of the events in soma and neurites (^***P<0.001). A total of 332 fusion events in soma and 48 events in neurites were analyzed in B, E and F.