[Characteristics and mechanism of pyelorenal backflow correlated to renal pelvic pressure].

The present study was conducted to examine the characteristics of pyelo-renal backflow related with the changes in renal pelvic pressure. Forty rabbits weighting approximately 3.0 kg were used in this experiment. The renal pelvis was continuously perfused with PSP solution through the double lumen catheter placed above the ureteropelvic junction. The renal pelvic pressure was also recorded during the intrapelvic perfusion. Simultaneously, PSP concentrations in blood and urine excreted from the contralateral kidney were measured. During the intrapelvic perfusion with PSP solution, PSP blood concentration began to increase immediately and reached maximum within 1 or 2 minutes after a start of perfusion. Then, its concentration gradually decreased toward the constant, low levels. The urinary concentration of PSP showed the same change as the blood concentration with a time lag of 1 or 2 minutes. A compartment analysis showed that this backflow curve composed of an early phase and a late phase. The early phase was characterized by a rapid increase and following decrease (exponentially declining) in PSP concentration. The late phase was a portion of constant PSP concentration in the backflow curve. A maximum PSP concentration in the early phase was elevated with an increase in the increment rate of renal pelvic pressure. There was a significant, positive correlation between the maximum PSP urinary concentration and the increment rate of renal pelvic pressure (dp/dt). The constant values of PSP concentration in the late phase could be correlated with neither increment rate nor absolute values of renal pelvic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)