Figure 1. [Ca²⁺]_i transients evoked by single APs (Aa, Ba) or by bursts of 10 APs at 100 Hz (Ab, Bb).

A, [Ca²⁺]_i transients recorded from an intact terminal ‘preloaded’ with about 100 μm Fura-6F during a brief episode of whole-cell recording. Afterwards the pipette was withdrawn and the terminal was stimulated by afferent fibre stimulation. Both the single stimulus response and the [Ca²⁺]_i transient following burst stimulation display a double exponential decay. B, responses to the same stimuli during whole-cell recording, after washout of a slow endogenous buffer. The decays can be fitted with single exponentials with average time constants of about 80 ms. Reproduced with permission from Müller et al. (2007).