Figure 4

Caffeine altered frequency, rise and decay times of Ca²⁺ sparks. (A) Original recordings of Ca²⁺ sparks in the absence (top trace), presence (middle trace) and washout (bottom trace) of 1 mM caffeine. Numbers beside transients indicate sparks. (B) Caffeine increased the frequency, rise and decay time of Ca²⁺ sparks but had no effect on Ca²⁺ spark amplitude. Recordings in the presence of caffeine were made at 10, 40 and 70s after drug application and recordings during washout were made at 10, 40 and 70s after termination of drug application. Time control experiments revealed that Ca²⁺ spark frequency, amplitude, rise time and time to half-decay were reasonably stable for nine 5 s line scans spread over 225 s.