To investigate the mechanisms for elicitation of peristaltic activity in the human colon, we studied the effect of balloon distension of the transverse, descending, and sigmoid colon and the rectum. Fifteen healthy subjects were studied by means of a colonoscopically positioned probe carrying a 5-cm latex balloon. After positioning of the probe, stepwise distension was performed for each colonic segment (transverse, descending, sigmoid, rectum), and the onset of large (> 50 mm Hg) and small (< 50 mm Hg) propagated waves was observed. Analysis of the tracings showed: (1) In 8/15 subjects (53.3%), balloon distension elicited propagated contractions, but these contractions were qualitatively different from the spontaneously occurring high-amplitude propagated contractions previously found to occur in association with defecation. Therefore, intraluminal distension is probably not the cause of defecation-associated high-amplitude propagated contractions. (2) Pain reports were poorly correlated with propagated contractions elicited by balloon distension, suggesting that these contractions are not the cause of the pain produced by balloon distension. (3) The transverse colon shows lower pressures, fewer pain reports, and fewer large propagated contractions in response to balloon distension as compared to the descending and the sigmoid colon.
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