JCS02540 Supplementary Material

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• Supplemental Figure 1 - Fig. S1. Spontaneous [Ca²⁺]_i oscillations observed in a cell cluster preparation. After loading Fluo-3 as an intracellular Ca²⁺ probe, Ca²⁺ images were acquired using a fluorescence CCD camera system. In order to isolate [Ca²⁺]_i oscillation in pacemaker cells (ICCs), 1 mM nifedipine was added to the extracellular (normal) solution. (A) A Ca²⁺ image acquired at basal time during an oscillation cycle. The time courses of [Ca²⁺]_i oscillations (indicated in red and blue lines in C) were measured in the regions 1 (R1) and 2 (R2) in (A). The fluo-3 fluorescence (as an index of [Ca²⁺]_i movement) is expressed relative to that at the initial basal time (F_t/F_0(t=ib)). The cross-correlation of the two time courses is plotted in D. The function was maximal (0.94) at t=0. A and B show pseudo-colour Ca²⁺ images acquired at basal and peak times of an oscillation cycle, respectively. Each pixel of the image was normalized to the corresponding pixel at the initial basal time.

• Supplemental Figure 2 - Fig. S2. Spontaneous [Ca²⁺]_i oscillations in the presence of cromakalim and nifedipine. (A) After observing [Ca²⁺]_i oscillations in the presence of 1 mM cromakalim (left panel), 1 mM nifedipine was added (right panel). (B) Another example of the same experiment. Note that the regions showing [Ca²⁺]_i oscillations were similar even after addition of nifedipine.