SURGICAL MANIPULATION OF THE GUT ELICITS AN INTESTINAL MUSCULARIS INFLAMMATORY RESPONSE RESULTING IN POSTSURGICAL ILEUS

Objective To investigate the pathophysiologic mechanisms that lead to ileus after abdominal surgery. Summary Background Data The common supp osition is that more invasive operations are associated with a more ex tensive ileus. The cellular mechanisms of postsurgical ileus remain el usive, and few studies have addressed the mechanisms. Methods Rats wer e subjected to incremental degrees of surgical manipulation: laparotom y, eventration, ''running,'' and compression of the bowel. On postsurg ical days 1 and 7, muscularis infiltrates were characterized immunohis tochemically. Circular muscle activity was assessed using mechanical a nd intracellular recording techniques in vitro. Results Surgical manip ulation caused an increase in resident phagocytes that stained for the activation marker lymphocyte function-associated antigen (LFA-1). Inc remental degrees of manipulation also caused a progressive increase in neutrophil infiltration and a decrease in bethanechol-stimulated cont ractions. Compression also caused an increase in other leukocytes: mac rophages, monocytes, dendritic cells, T cells, natural killer cells, a nd mast cells. Conclusion The data support the hypothesis that the deg ree of gut paralysis to cholinergic stimulation is directly proportion al to the degree of trauma, the activation of resident gut muscularis phagocytes, and the extent of cellular infiltration. Therefore, postsu rgical ileus may be a result of an inflammatory response to minimal tr auma in which the resident macrophages, activated by physical forces, set an inflammatory response into motion, leading to muscle dysfunctio n.