Sample amperometry traces at different temperatures. (A) 12°C. (B) 18°C. (C) 22°C. (D) 28°C. Depolarization by a KCl solution triggered release, and the application time for this solution is indicated by the thick bars below each trace. With this compressed timescale the features illustrated in Fig. 1 are not visible. These traces show the dramatic increase in the frequency of exocytotic events with increasing temperature. Cumulative spike counts pooled from many recordings are plotted in Fig. 3 A. (E) Expanded views of single-vesicle release events were overlaid to show the trends of how prespike feet and spikes change with temperature.