The effect of ryanodine on Ca²⁺ transients in ICC-MY. (A and B) Representative heat map showing the summated PTCLs for an entire 60× magnification recording of ICC-MY in control and ryanodine (100 µM) showing the inhibitory effects of ryanodine (A), as indicated in the occurrence map of individually color-coded Ca²⁺ firing sites in the ICC-MY network (B). (C) Traces of PTCL activity (PTCL area [dark blue] and PTCL count [brown]) in control and ryanodine. (D and E) Histogram showing the probability (%) that an individual Ca²⁺ firing site in the ICC-MY cell somata and cell processes in E will fire during a CTC cycle in control conditions (black bars) and ryanodine (100 µM; red bars; n = 5, FOV = 5). (F) The number of Ca²⁺ firing sites per cell soma was reduced from 6.28 ± 1.47 in control to 0.94 ± 0.81 in the presence of ryanodine (100 µM; P = 0.01, n = 5, FOV = 5). (G) PTCL area/frame was reduced in the cell somata from 62.19 ± 6.34 µm² in control to 0.3 ± 0.2 µm² in ryanodine (100 µM; P = 0.002, n = 5, FOV = 5). (H) PTCL count/frame was reduced in the cell somata from 2.5 ± 0.63 in control to 0.04 ± 0.03 in ryanodine (100 µM; P = 0.014, n = 5, FOV = 5). (I) In the cell processes, the number of Ca²⁺ firing sites per FOV was reduced from 70 ± 13.12 in control to 2.8 ± 2.33 in ryanodine (100 µM; P = 0.011, n = 5, FOV = 5). (J) PTCL area/frame was reduced in the cell processes from 169.1 ± 59.46 µm² in control to 1.3 ± 1.2 µm² in ryanodine (100 µM; P = 0.046, n = 5, FOV = 5). (K) PTCL count/frame was reduced in the cell processes from 4.57 ± 1.59 in control to 0.045 ± 0.043 in ryanodine (100 µM; P = 0.014, n = 5, FOV = 5). *, P < 0.05; **, P < 0.01. Mean ± SE is shown.