Fig. 1. Effects of ryanodine on [Ca²⁺]_i oscillations in the presence of nifedipine. Single or multiple [Ca²⁺]_i oscillation sites are seen in A or B, respectively. Aa1 to 3 show pseudo-colour ratio images of the fluo-3 fluorescent intensity recorded at lines 1 to 3 (indicated in Ab) from a cultured cell cluster preparation in the presence of 2 µM nifedipine. The fluo-3 fluorescence was used as an index of [Ca²⁺]_i activity. Each image was normalised by the fluorescent intensity of the initial image (acquired at t=0 in the first or third trace of Ab). The panels Aa4 and Aa5 show c-Kit-immunostaining and transmission images, respectively, obtained from the same cell cluster. Bar, 100 µm. Note that the square region in Aa1 showing [Ca²⁺]_i oscillations indicates c-Kit-immunopositivity. The traces in Ab show changes in [Ca²⁺]_i (fluo-3 intensity: F_t/F₀) in the square region. After observing control [Ca²⁺]_i oscillations in the presence of 2 µM nifedipine (left trace), 1 µM ryanodine was applied. The second (middle) trace of [Ca²⁺]_i oscillations was obtained 5 minutes after 1 µM ryanodine application. Subsequently, the ryanodine concentration was increased to 10 µM. The third (right) trace in Ab was obtained 5 minutes after increasing the ryanodine concentration. The three panels in Ba are pseudo-colour ratio images of [Ca²⁺]_i activity obtained from another cell cluster preparation showing multiple oscillation sites. Images Ba1 to Ba3 were acquired at lines 1 to 3 in Bb. In Bb the blue and red traces indicate changes in [Ca²⁺]_i in the square regions of x [=F_t(x)/F₀] and y [=F_t(y)/F₀] in panel Ba1. After observing control [Ca²⁺]_i oscillation in the presence of nifedipine (2 µM) (left trace in Bb), 10 µM ryanodine was applied to the extracellular solution. The second (middle) and third (right) traces were obtained 2 and 8 minutes after the application of ryanodine, respectively. In Bc, F_t(y)/F₀ (y-axis) is plotted against F_t(x)/F₀ (x-axis). Each graph Bd indicates the cross-correlation function between F_t(x)/F₀ and F_t(y)/F₀. Note, [Ca²⁺]_i oscillations in x and y are well correlated even when significantly impaired.