“Defective in vitro contractility of ureteropelvic junction in children with functional and obstructive urine flow impairment.”

Background/Purpose: Studies of children with urinary flow impairment (UFI) at the ureteropelvic junction (UPJ) have revealed prestenotic, stenotic, and poststenotic histologic changes. Muscle function, however, has not been investigated. We therefore evaluated in vitro UPJ contractility by tensiometry in children with UFI. Methods: Freshly excised UPJs from 11 children with UFI (6 functional, 5 obstructive) were each divided into 3 parallel, prestenotic, stenotic, and poststenotic rings, and those from 7 children with Wilms’ tumor were divided into proximal, medial, and distal segments. Each ring was studied in vitro by tensiometry in the basal state and after stimulation with 25 and 60 mmol/L KCl. Results: The stenotic rings from the UFI subjects displayed a significantly lower basal contractility than the other 2 rings, and their 25 and 60 mmol/L KCl–induced contractility was absent or severely reduced, whereas the values of these parameters were similar to that observed in controls in the other 2 rings of patients with either functional or obstructive UFI. Conclusions: Basal and KCl-induced contractility of the stenotic segment is severely impaired in children and infants with either functional or obstructive UFI, whereas the contractility of their pre- and poststenotic UPJ segments is similar to that recorded in controls.