Study of the effect of vesical filling and voiding on ureterovesical junctions and internal urethral meatus: the filling and meato-vesico-ureteral reflexes.

Abstract

The effect of vesical filling and voiding on bladder pressure, the ureterovesical junctions (UVJs), and the internal urethral meatus (IUM) was studied. A pressure catheter was introduced into each of the UVJs, the IUM, and the urinary bladder of 16 healthy volunteers (9 men, 7 women; mean age, 38.4 years) and their pressure response to vesical filling in increments of 50 mL and during voiding as well as on IUM distension was recorded. The tests were repeated after separately anesthetizing the bladder, UVJs, and IUM. When the bladder was filled to 250 mL, there was a significant increase (P < 0.01) in the pressure of the UVJs, IUM, and bladder, which continued to rise with bladder filling up to 350 mL (P < 0.001). There was no further pressure increase above 350 mL. During voiding, the bladder and UVJs pressures rose (P < 0.0001) while the IUM pressure dropped (P < 0.01). IUM distension caused a significant pressure rise in the bladder and UVJs and a drop of IUM pressure. These pressure responses did not occur upon separate anesthetization of the bladder, UVJs, or IUM. A reflex relationship appears to exist between vesical filling and an increase in UVJs and IUM pressure which was absent on anesthetizing the presumed 2 arms of the reflex arc, the filling reflex. Another reflex relationship may exist between IUM dilatation and the bladder and UVJs pressure increase, the meato-vesico-ureteral reflex. These 2 reflexes might help further delineate the mechanism of micturition.