Objective   To explore the effects of interstitial cells of Cajal in the ureter on the spontaneous contraction of smooth muscles.    Methods   The interstitial Cajal cells of ureter tissue were identified by c-kit immunofluorescence and laser scanning confocal microscopy. Smooth muscle strips were used to study the effect of Glivec on the spontaneous contraction of smooth muscles in vitro.    Results   By using immunofluorescence staining

c-kit-positive

ICC-like cells were found in the ureter of guineapigs. With a preload of 2.0 g

KCl (f

inal concentration 2×10

-2

mol/L) induced stable spontaneous contraction in the smooth muscle strips of control group. The frequency of spontaneous contraction was (6.8±1.6)times/min

and the amplitude was (0.104 5±0.021 6) g. After the smooth muscle strips of experiment group were incubated with Glivec (final concentration 10

-4

mol/L) for 30 min

KCl (final concentration 2×10

-2

mol/L) was added into them

but didn’t induce spontaneous contraction. Then the Glivec Kreb’s solution was substituted with normal Kreb’s solution without Glivec. After 30 min

the spontaneous contractions reoccurred in the muscle strips with a slightly decreased amplitude.    Conclusion   ICC-like cells of smooth muscles

which play a very important role in the spontaneous contraction of guinea-pig ureter

are most likely to be the pacemakers of ureter.