Fig. 3.
Decay of intraterminal calcium levels after stimulation. Shown is the decay of [Ca2+]i at the end of stimulation with 40 action potentials at the indicated fStimon linear (A) and logarithmic (B) time scales. The y-axis scale in B is identical to the one in A. Thesolid lines in A represent the raw data points. In B the raw data from A were resampled uniformly on a logarithmic time scale. The open circles in B are the results from double-exponential fits through the data. C, Changes in the shape of the decay phase of the 1st (——), 5th, and 15th (– – –) Δ[Ca2+]i response during action-potential stimulation atfStim = 15 Hz. D, Dependence of the amplitudes (open symbols) and time constants (closed symbols) of the double-exponential fits in B on stimulation frequency (⋄, constant background; ■, ▪, first and ○, ●, second fast component).