Loss of interstitial cells of Cajal and development of electrical dysfunction in murine small bowel obstruction.

1. Partial obstruction of the murine ileum led to changes in the gross morphology and ultrastructure of the tunica muscularis. Populations of interstitial cells of Cajal (ICC) decreased oral, but not aboral, to the site of obstruction. Since ICC generate and propagate electrical slow waves in gastrointestinal muscles, we investigated whether the loss of ICC leads to loss of function in partial bowel obstruction. 2. Changes in ICC networks and electrical activity were monitored in the obstructed murine intestine using immunohistochemistry, electron microscopy and intracellular electrophysiological techniques. 3. Two weeks following the onset of a partial obstruction, the bowel increased in diameter and hypertrophy of the tunica muscularis was observed oral to the obstruction site. ICC networks were disrupted oral to the obstruction, and this disruption was accompanied by the loss of electrical slow waves and responses to enteric nerve stimulation. These defects were not observed aboral to the obstruction. 4. Ultrastructural analysis revealed no evidence of cell death in regions where the lesion in ICC networks was developing. Cells with a morphology intermediate between smooth muscle cells and fibroblasts were found in locations that are typically populated by ICC. These cells may have been the redifferentiated remnants of ICC networks. 5. Removal of the obstruction led to the redevelopment of ICC networks and recovery of slow wave activity within 30 days. Neural responses were partially restored in 30 days. 6. These data describe the plasticity of ICC networks in response to partial obstruction. After obstruction the ICC phenotype was lost, but these cells regenerated when the obstruction was removed. This model may be an important tool for evaluating the cellular/molecular factors responsible for the regulation and maintenance of the ICC phenotype.