DELAYED GASTRODUODENAL EMPTYING IS AN IMPORTANT MECHANISM FOR CONTROLOF INTESTINAL TRANSIT IN SHORT GUT SYNDROME

PURPOSE: To understand the relative importance of changes in ileal smo oth muscle contractility versus alteration of intestinal flow rate as control mechanisms for regulating intestinal transit in a surgical mod el of short-gut syndrome. METHODS: A model of short-gut syndrome was c reated by performing a 70% proximal small bowel resection in dogs. Ten control and 6 animals with short-gut syndrome were instrumented with strain gauge transducers, steel collection cannulas, and a Silastic in traluminal infusion catheter in the midileum. Motor activity was analy zed by computer programs that determine frequency, amplitude, and prop agation behavior of postprandial contractions. Perfusions of C-14-poly ethylene glycol and bolus injection of H-3-polyethylene glycol were us ed to determine intestinal flow and transit rates. Total gastroduodena l emptying was determined using a C-14-polyethylene glycol-labelled me al. RESULTS: Postprandial contraction frequency was decreased in anima ls with short-gut syndrome, but other significant changes in amplitude , mean area, and propagation behavior of postprandial ileal contractio ns were not seen. Gastroduodenal emptying and mean intestinal flow rat es were markedly slower in animals with short-gut syndrome, as were in testinal transit rates. CONCLUSIONS: In this model of short-gut syndro me, the major adaptive change is decreased intestinal flow rate, relat ed to delayed gastroduodenal emptying. The spatial organization of ile al contractions does not change substantially aside from a change in f requency which can be accounted for by transection of the intestinal w all.