Figure 4.

High-potassium destaining kinetics of FM1-43-loaded synaptic varicosities in wild-type fish. A, Time-lapse images of three varicosities (indicated by arrows 1-3) during high-potassium-induced destaining. Representative images are shown at 12 sec intervals after perfusion of high-potassium solution. Scale bar, 10 μm. B, Time-course plot of fluorescence loss after background correction for the three individual varicosities shown in A. Time 0 is determined by the slight twitch of muscles with arrival of high-potassium solution. Fluorescence intensity was measured every 4 sec. The time required for decay from 90 to 10% of peak fluorescence determined for each trace is indicated alongside the corresponding legend bar.