Response of the renal pelvis and ureter to distension of the contralateral renal pelvis and ureter: identification of the reno-renal pelvic reflex.

For the study of the relationship of the pelviureteric system of one kidney to that of the contralateral one, bilateral cutaneous ureterostomy was performed in 14 dogs. The renal pelvis (RP) and ureter (U) of one side were distended separately with a balloon filled with saline in increments of 1 and 0.25 ml, respectively, and the pressure response of the contralateral RP and U was recorded. The test was repeated after anesthetization of the RP and U. RP distension with 1 ml of saline effected a pressure rise (P < 0.05) in the ipsilateral RP but no pressure response in the ipsilateral U or the contralateral RP or U (P > 0.05). RP distension with 2, 3, and 4 ml of saline induced a significant pressure rise in the ipsi- and contralateral RP but not in the ureters. Ureteric distension produced a pressure elevation (P < 0.05) on the ipsilateral U but had no effect on the contralateral U (P > 0.05) or on either of the renal pelves (P > 0.05). Distension of the anesthetized RP or U effected no pressure response in any of the ipsi- or contralateral RPs or Us. In conclusion, distension of the RP with large volumes led to an increase in pressure in the contralateral RP but not in the U. A reflex relationship is postulated to exist between the two renal pelves and to be mediated through a reflex we call the reno-renal pelvic reflex. It seems that this reflex acts to allow either of the kidneys to share an extra load of the other one by increasing the contractile activity of the RP, thus assumedly assisting the regulation of urine flow.