Interstitial cells of Cajal direct normal propulsive contractile activity in the mouse small intestine

BACKGROUND & AIMS: Interstitial cells of Cajal (ICC) have been linked to the generation of intestinal pacemaker activity, but their role in in vivo motor dysfunction is unclear. In this study, we investigated the hypothesis that ICC play a role in the generation of distention-induced peristalsis using W/Wv mice that lack ICC associated with Auerbach's plexus. METHODS: Radiological observations were made of the movement of contrast fluid through the proximal small intestine. Electrical activities were recorded in the external muscle layers. In addition, intraluminal pressure changes were recorded in isolated intestinal segments. RESULTS: In control mice, after gavage of 0.5 mL of barium sulfate in the stomach, the contrast fluid moved through the proximal small intestine in peristaltic waves at approximately 47 times a minute, propagating aborally at approximately 2 cm/s. Electrical slow waves and intraluminal pressure waves were synchronized at similar frequencies and propagation velocities. In W/Wv mice, such regular peristaltic waves were not observed. Action potentials and contractions appeared random, and contents moved back and forth in an irregular manner. The net propulsive effect of contractile activity in W/Wv mutant mice was much weaker than that in controls. CONCLUSIONS: Slow wave controlled peristalsis occurs in the normal proximal small intestine upon gastric emptying of a semiliquid. This motor pattern is absent in W/Wv mice that lack ICC.