: Irritable bowel syndrome (IBS) is a common problem that affects 10-17% of Americans, the majority of whom are women. IBS is characterized by abdominal pain with accompanying alterations in bowel patterns (diarrhea, constipation, or both). The etiology of IBS is likely multifaceted. Of the multiple factors involved, visceral hypersensitivity and brain-gut dysfunction are key. Our group has described autonomic nervous system (ANS) activity in women with IBS. We found that women who self report severe constipation exhibit: (1) lower vagal tone and higher sympathetic/parasympathetic balance relative to controls and those with diarrhea; and (2) elevations in night time catecholamines & cortisol. It remains to be determined whether these alterations are associated with visceral hypersensitivity. This proposal is a feasibility study of a visceral hypersensitivity study protocol that incorporates measures of ANS activity. Thus, the primary aim is to: (1) test the feasibility of recruiting a sample of women with severe constipation IBS and controls to complete a protocol that involves measurement of visceral hypersensitivity and HRV. Secondary aims are to: (1) describe visceral sensitivity in women with severe IBS-constipation and controls; and (2) describe salivary cortisol and urine catecholamine levels pre and post visceral sensitivity measures in women with severe IBS-constipation and controls. The results will demonstrate the feasibility of: (1) the barostat protocol to quantify visceral sensitivity; (2) the protocol to examine HRV and visceral sensitivity; and (3) recruitment plans. Because this is a feasibility study it is unlikely that there will be adequate data to test for group differences. However, we do hypothesize that trends will be noted in that visceral sensitivity will be enhanced, indices of vagal tone decrease, and greater increase in catecholamines and cortisol will be found following the barostat relative to pre-testing in women with severe-IBS constipation as compared to controls.
