UNILATERAL INCOMPLETE URETERAL OBSTRUCTION: RENAL FUNCTION DURING OBSTRUCTION AND ITS REVERSIBILITY AFTER RELEASE IN A NEW EXPERIMENTAL MODEL
1987 Volume 78 Issue 1 Pages 97-106
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1987 Volume 78 Issue 1 Pages 97-106
The present study investigates (1) a reliable method of incomplete ureteral obstruction (IUO) for creating a moderate unilateral hydronephrosis in the dog, and (2) functional evaluation on the renal damage caused by the IUO as well as its reversibility after release from the obstruction (RO). In the first experiment, 4 methods of IUO were evaluated using 29 canine ureters. Ureteral ligation, periureteral silicone prosthesis and ureteral embedding into the psoas muscle were all unsuccessful for this attempt. Only intravesical ureteral obstruction with a tapered polypropylene obturator resulted constantly in a moderate degree of hydronephrosis persisting for 7 weeks. The second experiment consisted of renal clearance study using separate renal urine, repeating for 7 weeks during IUO and further 7 weeks after RU in 10 dogs.
The results were as follows;
1) Glomerular filtration rate (GFR) of the IUO kidney decreased to 28% of that in the contralateral control kidney 1 week after obstruction. Then 41-48% level continued during 7 weeks of IUO. Postobstructive recovery of GFR was rapidly observed, reaching 70% and 84% levels after 1 and 7 weeks, respectively.
2) Renal blood flow (RBF), urine volume, excretion of potassium and osmolar substance in the obstructed kidney also showed a certain decrease during IUO and recovery after RU was seen in a similar pattern in each of them. Significant correlation was noticed among GFR, RBF and osmolar clearance throughout the period of observation.
3) The decrease of potassium excretion correlated well with that of GFR and RBF when the obstruction chronically persisted. The postoperative increase of potassium excretion also paralleled the recovery of GFR and RBF. The results indicate that the potassium excretion ratio of the obstructed kidney to the contralateral normal kidney is of a good predictive value for the potential reversibility of the obstructed kidney function.
4) Excretion of urinary sodium from the obstructed kidney appeared to be indifferent to any of the abovementioned parameters. It is even suggested that sodium excretion from the contralateral intact kidney can toe restricted by an unknown cause in this unilateral IUO model.
