Figure 2. Temporal sequence of Ca²⁺ transients firing in submucosal interstitial cells of Cajal (ICC-SM) and smooth muscle cells (SMCs).

Representative dual-color imaging of ICC-SM (green; A) and SMCs (red; B) Ca²⁺ transients were recorded simultaneously from proximal colonic muscles of Kit-iCre-GCaMP6f/Acta2-RCaMP1.07 mice (see Materials and methods for details). C and D Spatiotemporal maps (STMaps) of Ca²⁺ signals in ICC-SM and SMCs during a recording period (gray boxes in A and B denote cell locations; see Video 1). The STMaps show coordinated firing of Ca²⁺ transients in both types of cells. Ca²⁺ transient traces are plotted in E (ICC-SM-green, SMCs-red). Tissue displacement was also monitored and plotted (black trace; E). The black dotted arrow depicts the sequence of activation firing of Ca²⁺ transients in ICC-SM, to activation of Ca²⁺ events in SMCs, and tissue displacement. (F) A comparison of latencies (ms) from the start of the initiation of Ca²⁺ transients in ICC-SM to SMC activation and tissue displacement (n = 8). (G) Correlation analysis of latencies between ICC-SM and SMC Ca²⁺ transients and tissue displacement (R² = 0.82). All data graphed as mean ± SEM.