Impaired contractility of colonic muscle cells in a patient with chronic intestinal pseudo-obstruction

Chronic intestinal pseudo-obstruction represents a cause of persistent functional intestinal failure either “secondary” to specific conditionsor “chronic intestinal idiopathic pseudo-obstruction” in origin. The diagnosis is mainly clinical, supported by radiological and/or endoscopicfindings excluding any mechanical cause of intestinal obstruction.We reported a case of a 39-year-oldwoman with chronic intestinal idiopathicpseudo-obstruction, who underwent colectomy with ileorectal anastomosis; histological examination of the surgical specimen did not revealmyogenic or neurogenic defects or other pathological abnormalities indicative of an underlying neuromuscular impairment. Because of theapparent integrity of the gut neuromuscular layer, we tested whether a functional impairment affected colonic single smooth muscle cells.Muscle cells were isolated from the right colon and their contractile response to a receptor-dependent agonist evaluated in comparison tothat obtained from controls. The cell contraction induced by acetylcholine in a dose response manner was markedly decreased in the patientaffected by chronic intestinal idiopathic pseudo-obstruction compared with cells from controls (percentage of cell shortening with maximaldose of acetylcholine [10−6 M]: 10.7±3% versus 34.2±4%, respectively). The present findings indicate a specific defect of colonic smoothmuscle cells likely related to an ineffective response to acetylcholine.