Figure 6. The decrease of Cx43 protein expression in the mouse GI tract with aging. Expressions of Cx43 within GI longitudinal muscle layer of 2-, 12-, 16-, 20- and 24-mo-old mice were examined by western blotting, and the decline in Cx43 expression was seen from 16 mo in all three organs (A-C). The densitometric analysis of protein expressions normalized to β-actin. Confocal images (D) of double immunofluorescence labelling for Cx43 (green) and c-kit (red) displayed that Cx43-puncta distributed throughout MP of colon, and some co-localized with ICCs (arrows), and in 16- and 24-mo-old mice, Cx43-puncta per field was significantly sparse compared with 2-mo-old mice, prior to the reduction in c-kit-positive area in 24-mo-old mice (D-F). Statistical analysis was performed using one-way analysis of variance and data were represented as mean ± SD, statistical significance is: ### P < 0.001 compared with 2-mo-old group; * P < 0.05, *** P < 0.001 compared with previous group; n=5 mice per group. Abbreviation: Sto, stomach; Jej, jejunum; Co, colon.