Objective:To investigate the possible role of altered quantity of colonic mucosa NO in the abnorˉmal intestinal motility and visceral perception in patients with IBS.Methods:Anorectal motility and rectal visceral perception were examined in patients with diarrhea and constipation predominant IBS and in healthy controls(n=30,n=30,and n=25respectively)by means of electric barostat and perfusion catheter manomeˉter.The quantity of NO was measured using nitrate/nitrite colorimetric assay.Results:The results showed that thresholds of first perception,defecation and pain in patients with diarrhea_predominant IBS were signifiˉcantly lower than those in control(P<0.05),no significant difference was observed between constipation-predominant IBS and controls(P>0.05).The motility indexes of sigmoid and rectum were significantly higher than those in controls in patients with diarrhea_predominant IBS(P<0.05),but significantly lower than those in controls in patients with constipation_predominant IBS(P<0.05).The quantity of colonic mucosa NO in paˉtients with diarrhea_predominant IBS was significantly lower than that in controls and showed a negative relaˉtionship with motility index,a positive relationship with thresholds of first perception,defecation and pain(P<0.05),but significantly higher than that in controls and showed a negative relationship with motility index in patients with constipation_predominant IBS(P<0.05).Conclusion:The alteration of colonic mucosa NO may play a major role in the mechanism of the abnormal intestinal motility and visceral perception of diarrhea_and constipation_predominant IBS.
