RESERVOIR CHARACTERISTICS OF MAINZ POUCH STUDIED IN ANIMAL-MODEL - OSMOLALITY OF FILLING SOLUTION AND EFFECT OF OXYBUTYNIN

In a canine model of the Mainz pouch, intracavitary pressure and compl iance were measured during instillation of isosmotic and hyperosmotic (900 mmol/kg water) solutions of saline. Wall properties of small- and large-bowel segments of the pouch were assessed individually by sonom icrometry. Intraluminal pressures increased more steeply during fillin g with hyperosmotic solution, resulting in reduced distensibility of s mall- and large-bowel segments. Additionally, instillation of the hype rosmotic solution resulted in increased amplitudes and frequency of in tracavitary pressure waves. The results indicate that this was the res ult of a combination of intensified bowel contractions and an increase d mural tension. Topical application of oxybutynin abolished these eff ects. These findings are reviewed in light of the nocturnal increase i n urine osmolality, its correlation with nocturnal incontinence in pat ients with enterocystoplasty, and possible treatment choices.