FIGURE 2.

Effect of caffeine stimulation for various durations on [Ca²⁺]_i. (A) Original traces of cells stimulated by 5 mM CAF for 30 s, 5 s, and 1 s. (B) Mean [Ca²⁺]_i decay upon stimulation with 5 mM CAF for 30 s (▪), 5 s (□), and 1 s (shaded squares). Time 0 corresponds to max [Ca²⁺]_i increase (peak). Values are expressed as percent of the peak obtained when cells were stimulated for 30 s (reference peak), 0 corresponding to baseline. Each curve is the mean value from 10 to 12 cells. (C) Effect of CAF ejection on fluorescence intensities and ratio. CAF was ejected for 5 s on a cell preincubated for 11 min with 10 μM CPA. During CAF ejection, fluorescence quenching at both wavelengths is observed, without alteration in the fluorescence ratio. Fluorescence intensities and ratio are in arbitrary units.