Characteristics of anal canal motility after ileoanal anastomosis.

This study attempted to determine the mechanism of anal canal motility after ileoanal anastomosis with the use of alpha-, beta- and muscarinic receptor agents. Forty-five patients, 19 +/- 2 months after operation (mean plus or minus S.E.M.) and 48 control volunteers were studied. Anal manometry indicated no difference in maximum resting pressure and squeeze pressure between the patients and the normal controls. Greater amplitude and less frequent anal canal slow waves were a particular characteristic during the postoperative period. Phentolamine (alpha-blocker) exhibited a stimulatory effect on anal resting tone in the normal rectum, while propranolol (beta-blocker) and atropine (muscarinic blocker) had no effect. However, alpha-, beta- and muscarinic receptors all had stimulatory effects on postoperative anal tone. The muscarinic receptor had dominant effects on the reduction in anal canal slow wave frequency after ileoanal anastomosis. Our results indicated that neorectum after ileoanal anastomosis had hybrid characteristics of both rectum and ileum. Through analysis of receptor-related motor function, we may be able to improve our understanding of dyscontinence after ileoanal anastomosis.