Contralateral response in renal pelvic pressure and diuresis during increasing ipsilateral pelvic pressure and flow: a study of the normal and denervated upper urinary tract in pigs.

OBJECTIVE

To examine, in young pigs, changes in baseline pelvic pressure and diuresis in the contralateral kidney during conditions of increasing pelvic pressure and perfusion with isotonic saline in the ipsilateral renal pelvis; the role of a reno-renal nervous mechanism was examined by denervating the kidneys, and the effect of bladder filling on these variables assessed.

MATERIALS AND

METHODS

Female pigs (37-40 kg) were assessed under general anaesthesia. Transparenchymally, one 6 F and two 6 F catheters were introduced into the right and left renal pelvis, respectively. Through a bladder incision an 8 F catheter was introduced 10 cm into the right ureter to collect urine and the orifice closed around the catheter. For bladder drainage and to measure bladder pressure a 10 F catheter was placed in the bladder and both the 8 F and 10 F catheters lead out through the urethra. In group A, five animals served as controls, with group B comprising eight with intact nerves and group C eight with denervated kidneys. In group B and C the left renal pelvis was perfused with isotonic saline at 2, 4, 6, 8, 10, 12 and 16 mL/min while the bilateral pelvic pressure and right renal diuresis were recorded; the bladder was kept empty and 0.5 h later the left pelvis was perfused with 10 mL/min while the bladder catheter was closed. Perfusion continued until micturition occurred. The bilateral pelvic pressure, bladder pressure and right renal diuresis were recorded. In group C the kidneys were surgically denervated, dividing all adhesions and all connective tissue around the pelvis and the vascular pedicle. The renal artery was freed to the aortic level.

RESULTS

During the pressure-perfusion study the mean (sd) right pelvic pressure was 7.4 (0.2) mmHg in group B and 8.6 (0.2) mmHg in group C. The diuresis from the right kidney in both groups was similar and the same as that in group A. The perfusion rate and pressure on the left side had no influence on pelvic pressure and diuresis on the right side. During perfusion with a full bladder the right pelvic pressure was 8.6 mmHg in group B and 9.5 mmHg in group C. Diuresis in group B was approximately 0.6 mL/min and a little higher in group C, at approximately 1 mL/min, but identical to that in group A.

CONCLUSION

These results indicate that a reno-renal reflex mechanism has no apparent role in young pigs during pressure-perfusion measurements with an empty or full bladder.