EFFECTS OF FRACTIONATED ABDOMINAL IRRADIATION ON SMALL-INTESTINAL MOTILITY - STUDIES IN A NOVEL IN-VITRO ANIMAL-MODEL

Disordered small intestinal motility occurs frequently during acute ra diation enteritis. However, th characteristics and time course of the motor dysfunction are poorly defined. These parameters were assessed i n a novel animal model of radiation enteritis. Ileal pressures were re corded in vitro with perfused micromanometric catheter using an arteri ally perfused ileal loop in 22 ferrets following fractionated abdomina l irradiation (9 doses 2.50 Gy thrice weekly for 3 weeks). Tissue dama ge was graded histologically. Studies were performed 3 to 29 days afte r irradiation. Tissue from 7 control animals was also studied. All tre ated animals developed diarrhoea. Histology showed changes consistent with mild to moderate radiation enteritis. Following irradiation, ther e was an initial increase in frequency followed by a non-significant r eduction in the frequency, but not the amplitude of ileal pressure wav es. The frequency of pressure waves showed an inverse relationship wit h time after radiation (r = -0.634, p < 0.002). There was no relations hip between motility and histology. We conclude that abdominal irradia tion is associated with a time-dependent reduction in ileal motility w hich does not correlate with light microscopic changes.