VISCERAL PERCEPTION IN IRRITABLE-BOWEL-SYNDROME - RECTAL AND GASTRIC RESPONSES TO DISTENSION AND SEROTONIN TYPE-3 ANTAGONISM

We wished to determine if visceral perception in the rectum and stomac h is altered in patients with irritable bowel syndrome and to evaluate the effects on visceral sensation of 5-HT3 receptor blockade. Twelve community patients with diarrhea-predominant irritable bowel syndrome and 10 healthy controls were studied in a double-blind, randomized, pl acebo-controlled study. Using two barostats, the stomach and rectum we re distended, with pressure increments of 4 mm Hg, from 10 to 26 mm Hg ; visceral perception was measured on an ordinal scale of 0-10. Person ality traits were measured using standard psychological methods, and s omatic pain was evaluated by immersion of the nondominant hand in cold water. The effect of 5-HT3 antagonism was tested with a single intrav enous dose of ondansetron at 0.15 mg/kg. Gastric perception was higher in irritable bowel syndrome, but rectal distension was perceived simi larly in irritable bowel syndrome and controls. Pain tolerance to cold water was also similar in irritable bowel syndrome and controls. Onda nsetron induced rectal relaxation and increased rectal compliance but did not significantly alter gastric compliance or visceral perception. Psychological test scores were similar in patients and controls. We c onclude that in this group of psychologically normal patients with irr itable bowel syndrome. who were not chronic health-care seekers, visce ral perception was normal. Ondansetron dib not alter gut perception in health or in irritable bowel syndrome.