Distension of the intestine is commonly used to elicit reflex responses at other sites in the gastrointestinal tract, and also to evaluate @entity158 of intestinal origin. The sensory neurones, that initiate the reflexes or @entity158 responses, react to the forces generated in the wall of the intestine. Thus, the responses of the intestine at the site of distension, particularly changes in contractile activity, influence the signals from the gut. In the present work we have analysed the relationship between distension and pressure changes in the jejunum of the @entity35 , in vivo. Isovolumic distension for 5 min caused an initial pressure increase which declined quickly in the first 30 s, and then declined more slowly. Phasic pressure increases were superimposed on the baseline pressure change. @entity4033 blocked the phasic pressure increases, whereas the initial rapid and subsequent slower pressure decline during distension persisted. Inhibition of @entity842 synthase (NOS) increased intraluminal pressure and caused increased frequency and irregularity of phasic pressure increases. However, the decline in jejunal pressure during distension was not changed by inhibition of NOS. The pressure decline during isovolumic distension was similar whether saline or paraffin oil were used to distend the intestine, indicating that the decline was not due to increased hydrostatic pressure causing water and electrolyte to cross the mucosal epithelium from the lumen to the intestinal interstitium. @entity5591 had no significant effect on the pressure profile when the intestine was distended. However, when the systemic or the local circulation of the jejunum was infused with @entity3360 , the pressure that was achieved during isovolumic distension was less, although the rate of change in pressure during the slow decline was similar. It is concluded that distension evokes phasic pressure increases in the jejunum, that are nerve-mediated, and increases the tension in the wall through a stretch-activated increase in contractile force generated by the circular muscle. The decline in pressure during maintained distension is primarily a consequence of visco-elastic properties of the wall of the intestine.

Analysis of factors that determine the compliance of XXXX jejunum to distension in vivo.

@entity4033 :: ('MESH:D018738', 'Chemical') :: ['Hexamethonium'] @entity3360 :: ('MESH:D009529', 'Chemical') :: ['nicardipine'] @entity842 :: ('MESH:D009569', 'Chemical') :: ['nitric oxide'] @entity158 :: ('MESH:D010146', 'Disease') :: ['pain'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity5591 :: ('MESH:D012601', 'Chemical') :: ['Hyoscine']
@entity35 :: (10116,Species) :: ['rat']
