Control of gallbladder contractions by cholecystokinin through cholecystokinin-A receptors on gallbladder interstitial cells of cajal

Figure 1 Overview of CCKAR-immunoreactive ICC seen on cross section of guinea pig gallbladder. A: Low-magnification montage showing C-kit positive cells (arrow) distributed over a band of gallbladder muscle adjacent to the mucosa; B: Low-power montage showing CCKAR-immunoreactive cells distribute mainly in the muscular layers of guinea pig gallbladder; C: Compound micrographs from (A) and (B). Some, but not all C-kit immunoreactive (green) ICC colocalize CCKAR (red), meanwhile, not all CCKAR-immunoreactive cells are ICC; D: Phase-contrast micrographs of the same gallbladders wall at the same magnification.

Figure 2 Colocalization of CCKAR immunoreactivity with markers for ICC, kit in guinea pig gallbladder cultured ICC. CCK-AR immunoreactive ICC in the muscle of the gallbladder is distinctive of their labled processes. ICC possessed several processes (A-D); C-kit immunoreactive (green) ICC colocalize CCKAR (red); C: Compound micrographs from (A) and (B); D: Phase-contrast micrographs of the same gallbladder ICC at the same magnification; Often two or more labled ICC were aggregrated into a network (E-H), making it difficult to discern the individual cells; C-kit immunoreactive (green) ICCs colocalize CCKAR (red); G: Compound micrographs from (E) and (F); H: Phase-contrast micrographs of the same gallbladder ICCs at the same magnification; All these ICCs were big and had a large and angular nucleus; Bar (in D) 30 &mgr;m for (A-D) and (in (H)) 30 &mgr;m for (E-H).

Figure 3 Effect of atropine and TTX on CCK-8 induced contraction of gallbladder muscle strips. The addition of atropine (10^-6 mol/L) or TTX (3 × 10^-7 mol/L) to the medium had no effect on the control dose-response curve for CCK-8. Each value is the mean ± SE obtained in 5 observations and observed at 10^-10, 10^-9, 10^-8, 10^-7, 10^-6 mol/L. Series 1: CCK-8+TTX; Series 2: CCK-8+atropine; Series 3: CCK-8 alone.

Figure 4 Effects of CCK-8 on contraction of gallbladder muscle strips in vitro. Removing the ICC of the gallbladder significantly shifted the control dose-response curve to the right. Each value is the mean ± SE obtained in 5 observations and observed at 10^-10, 10^-9, 10^-8, 10^-7, 10^-6 mol/L. Series 1: Common gallbladder muscle strip; Series 2: Gallbladder muscle strip removed ICC.

Figure 5 The effect of methylene blue with light on gallbladder ICC. After incubation with methylene and light, ICC on gallbladder was swollen and had low cytoplasmic, and the nucleolus became smaller and processes diminished.