Recovery period from ureteral obstructions of different duration and severity in the rat kidney.

The relationship between the period for recovery from hydronephrosis and the characteristics of the obstruction still needs to be clarified. In rat kidney the left ureter was completely obstructed for 3, 7, 14 and 21 d and the renal function was measured by renal scintigraphy using 99mTC-dimercaptosuccinic acid 3, 7 and 14 d after the obstruction was removed. In addition, recovery from unilateral partial obstruction (PO) of different degrees of severity for 7 d was examined. The kidneys with very mild PO recovered within 3 d and those with a very long period of complete obstruction (CO) did not exhibit any significant recovery. However, most of the kidneys with CO of various durations and those with 7 days PO of various degrees of severity exhibited maximum recovery 7 d after the release of the obstruction. This study suggests that the period required for maximum recovery from hydronephrosis is usually constant, unless the obstruction is too mild to cause any damage or too long to permit any recovery.