Fig. 5.

AP-induced fluorescence response for each Ca_V1.1 VSD. (A–D) Normalized traces of average AP-induced fluorometric records (n = 3 to 5) of each of the individual VSDs (as indicated) in relation to optically measured AP (dark yellow trace), APVC-elicited charge movement (Q; gray, data from Fig. 2I) and AP-evoked fluo-4 Ca²⁺ transient (Ca²⁺; black) and corresponding Ca²⁺ release flux waveform (Rel; green trace, data from Fig. 2I). VSDs, Ca²⁺ transient and Ca²⁺ release signals were assessed in different sets of fibers and are presented ±SEM. AP, Q, Ca²⁺ transients, and derived Ca²⁺ release flux, were obtained from control untransfected muscle fibers (n = 11 to 12). TAMRA signals are shown as −ΔF/F0. Peak −ΔF/F0 responses for all VSDs ranged from 0.008 to 0.03 (a.u.). AP, Ca²⁺ transient, VSDs fluorescent signals were elicited by field stimulation (1 ms, 20 V) at time 0. Vertical dashed lines indicate time for Q = Q_max.