EXPERIMENTAL STUDY OF HYDRONEPHROSIS

Abstract

Kidneys in rats were made hydr onephrotic by unilateral ligation of the ureters close to the bladder. Succinate cytochrome C reductase (SCR) and lactic dehydrogenase (LDH) were measured in the hydronephrotic and the contralateral kidneys.
Changes of weight and gross appearance of the kidneys were observed and histological studies were made on hydronephrotic kidneys.
1) SCR and LDH in the kidneys with ureteral obstruction for 3 days were significantly lower than those of control group. At this time of ureteral obstruction, the renal pelvis is slightly dilated but atrophy of the renal parenchyma has not yet occurred judging from the change of dry weight ratio. It seems that there is a definite metabolic alteration in the kidney in the early stage of ureteral obstruction.
2) SCR and LDH progressively decreased in activity until 3 weeks of ureteral obstruction with no significant change in activity thereafter. SCR and LDH in the contralateral kidneys showed no change from those of control group up to 7 weeks of ureteral obstruction.
3) Histologically, renal tubular epithelium was destroyed in some areas in kidneys with ureteral obstruction of more than 2 weeks and interstitial connective tissue became rather prominent. Glomeruli were preserved relatively well even in kidneys with ureteral obstruction of long duration (6 or 7 weeks).
Ureteral obstruction was released by means of ureteroneocystostomy. Contralateral nephrectomy was performed 4 weeks after ureterocystoneostomy and the remaining kidney was also removed one week later. Serum creatinine was measured 48 hours and one week after contralateral nephrectomy.
Intravenous pyelography (IVP) was performed 4 weeks after ureteroneocystostomy and just prior to contralateral nephrectomy to check the patency of ureteroneocystostomy. SCR and LDH were measured in the removed kidneys whose ureteral obstruction had been released 5 weeks before. Histological studies were also made on these kidneys.
4) The kidneys with ureteral obstruction of more than 4 weeks' duration did not recover sufficiently to sustain life after release of ureteral obstruction.
5) Renal function after release of ureteral obstruction roughly was correlated with renal SCR but not with LDH.
6) Histologically, the kidneys with ureteral obstruction of short duration remained almost normal after release of ureteral obstruction. However, in the kidneys with ureteral obstruction of long duration (3 or 4 weeks), destroyed and well preserved areas were noted intermingled after release of ureteral obstruction.
7) The kidneys whose ureteral obstruction had been released by means of ureteroneocystostomy became visualized on IVP. This shows that release of ureteral obstruction using ureteroneosystostomy is technically successful. The longer the duration of ureteral obstruction prior to ureteroneocystostomy, the larger the renal pelvis and the poorer the excretion of contrast medium.
8) In this experimental model, there was no difference in enzyme activities between kidneys with ureteral obstruction for 3 weeks (reversibly damaged) and those with ureteral obstruction of 4 weeks
(irreversibly damaged) before release of obstruction. Histological distinction also could not be made between these two groups before release of obstruction.