Dynamics of the urinary tract in longterm vesico-ureteric reflux and infravesical obstruction in pigs. IV.

The dynamic function of the urinary tract was studied in 6 infravesically obstructed pigs with vesico-ureteric reflux to a total of 8 ureters. After 10 weeks of obstruction a bladder hyperreflexia was found. The baseline ureteric activity in the refluxing ureters was reduced to a median of 0.3 A.P./min (action potentials/min). During bladder filling, the activity increased only slightly to 0.6 A.P./min. In the start the pelvic pressure was more or less independent of the bladder pressure, but when the reflux producing bladder pressure was reached then an abrupt increase in pelvic pressure was seen and thereafter there was pressure equilibration. Ten weeks after release of the obstruction, a minor restitution had taken place. The baseline activity during low urine output was 1.0 A.P./min and during bladder filling it was unaltered, 1.0 A.P./min. Even during high urine output there was no sign of activity increase. 30% of the ureteric contractions stopped in the mid-third of the ureter. Almost all peristalsis was antegrade. Thus, ureters subjected to obstruction and reflux showed deterioration of the peristaltic function and the changes were irreversible.