Abstract
PURPOSE: To verify the differences in the reversibility of renal function and damage in rats of different ages with unilateral ureteral obstruction (UUO). METHODS: Sixty rats were divided into three different groups, newborns, young, and adults. Twenty-one were sham operated. After UUO, the animals were subdivided into four groups: obstruction (two weeks and sacrifice O2); UUO two weeks, obstruction release for two weeks and sacrifice (R2); UUO for four weeks and sacrifice (O4); and UUO for four weeks, obstruction release for two weeks and sacrifice (R4). Urine was collected for creatinine, urea, total protein, and albumin dosages, and kidneys for morphological studies. RESULTS: Younger rats presented more extensive destruction of renal parenchyma, with some remaining normal tissue healthier in comparison to older rats. The protein excretion by older rats was not different between the groups obstructed for different periods, albuminuria was progressively higher in rats obstructed for longer periods, and after relief of obstruction, there was no difference between newborn rats obstructed for different periods. The younger pyelostomized rats presented higher albumin excretion. Creatinine excretion was worsened in rats after obstruction. CONCLUSION: Shorter obstruction periods lead to better prognosis, and younger rats showed better recovery after relief of obstruction than older ones.