URETEROVESICAL JUNCTION INHIBITORY REFLEX AND VESICOURETERAL JUNCTIONEXCITATORY REFLEX - DESCRIPTION OF 2 REFLEXES AND THEIR ROLE IN THE URETERAL ANTIREFLUX MECHANISM

The purpose of this study was to investigate the response of the urete rovesical junction (UVJ) to ureteric distension and to bladder filling with the aim of elucidating the mechanism of UVJ antireflux. The stud y was performed on 13 healthy volunteers [age 41.4 +/- 10.2 (SD) years ; nine men, four women]. A ureteric catheter connected to a pressure t ransducer was introduced into the ureter proper. After recording the u reteric pressure, the catheter was withdrawn to the bladder, and the r esting pressures in the UVJ and bladder were registered. The catheter was positioned in the UVJ and a 3F balloon-tipped ureteric catheter wa s introduced into the ureter proper and filled with saline in incremen ts of 1 ml. The pressure response of the ureter and UVJ to ureteric di stension was recorded. The bladder was then filled with 400 ml saline at two rates, slow (10 ml/min) and rapid (150 ml/min), and UVJ pressur e response was registered. The aforementioned tests were repeated afte r anesthetizing the UVJ, the bladder musculature surrounding the UVJ a nd the ureteric wall at the site of the ureteric distension, respectiv ely. Ureteric distension of the lower 2-3 cm effected ureteric pressur e elevation (P < 0.05) and a UVJ pressure drop (P < 0.05); no pressure response of the UVJ occurred upon ureteric distension above this leve l. Slow bladder filling induced an increase in the UVJ (P < 0.01) and vesical (P < 0.01) pressures only when vesical filling reached a mean of 219.6 +/- 79.4 ml and above. Upon rapid vesical filling, the pressu re response occurred at a smaller volume (136.6 +/- 52.3 ml). The pres sure response did not occur when the UVJ was anesthetized. The study s howed that lower ureteric distension was associated with a UVJ pressur e drop. This reflex relationship, which we call the ''ureterovesical j unction inhibitory reflex,'' was reproducible and disappeared on anest hetizing the UVJ or ureter. Vesical filling above a certain volume ind uced a UVJ pressure increase which was reproducible and disappeared on anesthetizing the UVJ; we call this reflex relationship the ''vesicou reteral junction excitatory reflex.'' These two reflexes seem to regul ate the entry of urine from the ureters to the bladder and prevent ure teric reflux during bladder filling. In conclusion, two reflexes are i dentified that might contribute to the mechanism of UVJ antireflux.