Renal pelvis pressure flow relationship in pigs after transsections of the ureter

The relationship between pressure and flow of the multicalyceal renal pelvis of the pig was investigated in 10 units. The relationship was studied in the intact system and after three consecutive transsections of the ureter 3 cm proximal to the ureterovesical junction, at the lower pole of the kidney and as proximal on the renal pelvis as possible. The mean resting renal pelvic pressure changed from 7.3 to 8.8 cm H2O when a distal transsection was performed. The resting pressure after proximal transsection and pelvic transsection was 8.0 and 6.5 cm H2O respectively. During perfusion the intact system as well as the distal transsection showed a three-phased relationship. In the latter the phases showed a shift to the right and the renal pelvic pressure was significantly decreased at flow rates from 4-10 ml/ureter/min. Perfusion after proximal transsection and pelvic transsection caused only minor increases in the renal pelvic pressure approximating a linear relationship. The study confirms a three-phased relationship between pressure and flow in renal pelvis and a resistance to high flow rates depending on the length of the ureter.