Fig. 4

Depression of Ca²⁺ release during tetanic stimulation. a The calculation of the fluorescence transients elicited by each pulse during a 20-Hz train. The experimental record is represented by the black trace. The brown (a) and blue traces (b) are the envelopes to the peak and the inter-pulse fluorescence values along the train. The green trace (c) representing the amplitude of the fluorescence transients evoked by each action potential was obtained by subtracting (b) from (a). b Comparison of the mean ratio of Ca²⁺ fluxes in response to the first and last action potential of trains of 10, 20, 50, and 100 Hz in WT (n = 14) and C3KO (n = 18) fibers. Asterisks indicates statistical significance (p < 0.05)