Objective To explore the expression of connexin 43 in the interstitial cells of Cajal (ICCs) from guinea pig bladder in vitro.  Methods Bladder ICCs were primarily cultured from guinea pigs by collagenase digestion method. Primarily cultured bladder smooth muscle cells (SMCs) from guinea pig were taken as control. The expressions of c-kit and smooth muscle actin (SMA) were detected by immunofluorescent method. Immumofluorescent method and Western blotting were used to detect the expression of Connexin 43 in 2 groups of cells.  Results The expression of c-kit was positive in ICCs but negative in the control group. On the contrary

the expression of SMA was negative in ICCs but positive in the control group. Connexin 43 expression was significantly higher in ICCs than that in the control group (P0.01).  Conclusion High expression of connexin 43 might be the important for the signal transmission in bladder ICCs of guinea pigs.