EFFECT OF RADIATION AND RADIOPROTECTION ON SMALL-INTESTINAL FUNCTION IN CANINES

Radiation with doses >7.5 Gy damages the canine intestinal mucosa, and pretreatment with WR2721 reduces this damage. However, the effects of radiation and of WR2721 on in vivo intestinal transport are unclear. Therefore, we determined canine survival, intestinal transport, and mu cosal histology following unilateral abdominal irradiation. Isoperista ltic ileostomies were prepared in 23 dogs under general anesthesia and aseptic conditions. After a three-week recovery period, animals were given either placebo or WR2721, 150 mg/kg intravenously, 30 min prior to 10 Gy cobalt-60 abdominal irradiation. Ileal transport and histolog y were determined in both groups before exposure and one, four, and se ven days after irradiation. Seven-day survival was significantly impro ved by pretreatment with WR2721 (91% vs 33%, P < 0.02). On day 4, both mucosal integrity and net intestinal absorption were significantly be tter (P < 0.05) after WR2721 than after placebo. Thus, radiation-induc ed damage to the ileal mucosa is accompanied by a reduction in net ile al absorption of water and electrolytes in vivo. In addition, pretreat ment with WR2721 improves animal survival while reducing ileal damage and improving intestinal absorption.