Small intestinal dysmotility following abdominal irradiation in the rat small intestine

Abdominal symptoms such as diarrhoea, abdominal cramps and vomiting are com mon during and after abdominal radiotherapy for gynaecological and pelvic m alignancy. It has recently been recognized that small intestinal dysmotilit y may contribute to these symptoms but the underlying mechanisms are unclea r in part because of the technical difficulties inherent in performing stud ies in irradiated small intestine. The aim of the current study was to eval uate small intestinal motor activity using perfused micromanometric techniq ues in 6-8-cm segments of ileum during arterial perfusion with isotonic oxy genated fluorocarbon solution. intestinal segments from six rats were studi ed 4 days after treatment with 10 Gy abdominal irradiation. Ileal segments from nine nonirradiated animals acted as controls. For each experiment the total number of pressure waves, high-amplitude (>20 mmHg, long-duration >6 sec) pressure waves, and long (>20 associated) bursts of pressure waves wer e determined. Irradiation had no effect on the overall number of pressure waves, but incr eased high-amplitude long-duration (HALD) pressure waves (248 vs 7, P < 0.0 1). in control animals HALD waves were localized to a single recording site but after radiotherapy 74% of HALD waves were temporally associated with s imilar pressure waves in other manometric channels. Forty-seven per cent of associated HALD waves migrated aborally. Retrograde migration of HALD wave s was seen in five segments following irradiation. Irradiation abolished bu rsts of >20 pressure waves. High-amplitude contractions which migrate aborally are likely to contribute to diarrhoea after abdominal irradiation. The in vitro small animal model of radiation enteritis will permit interventions to provide further insight s into the mediation of intestinal dysmotility.