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 t he hypothesis that ICC play a role in the generation of distention-ind uced peristalsis using W/W-v mice that lack ICC associated with Auerba ch's plexus. Methods: Radiological observations were made of the movem ent 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 seg ments. Results: In control mice, after gavage of 0.5 mt of barium sulf ate in the stomach, the contrast fluid moved through the proximal smal l intestine in peristaltic waves at similar to 47 times a minute, prop agating aborally at similar to 2 cm/s. Electrical slow waves and intra luminal pressure waves were synchronized at similar frequencies and pr opagation velocities. In W/W-v mice, such regular peristaltic waves we re not observed. Action potentials and contractions appeared random, a nd contents moved back and forth in an irregular manner. The net propu lsive effect of contractile activity in W/W-v mutant mice was much wea ker than that in controls. Conclusions: Slow wave controlled peristals is occurs in the normal proximal small intestine upon gastric emptying of a semiliquid. This motor pattern is absent in W/W-v mice that lack ICC.