ELEVATED TUBULAR PROTEINURIA, ALBUMINURIA AND DECREASED URINARY N-ACETYL-BETA-D-GLUCOSAMINIDASE ACTIVITY FOLLOWING UNILATERAL TOTAL URETERAL OBSTRUCTION IN RATS

Urinary tubular proteinuria and N-acetyl-beta-D-glucosaminidase (NAG) activity has not yet been studied after unilateral total ureteral obst ruction (UTO). The aim of the study was (1) to evaluate in a longitudi nal study (7 weeks) the behaviour and the potential clinical value of tubular proteinuria and urinary NAG activity after UTO; (2) to study t he physiopathology of the non-obstructed contralateral kidney by using these two different markers of tubular damage. Methods: in 28 female, adult Wistar rats (UTO: n = 16, sham: n = 12), tubular proteinuria an d urinary NAG activity were measured before and 1 and 5 weeks after su rgery. Results: a significant (P < 0.01) increase in tubular proteinur ia/creatinine ratio and urinary creatinine and a decrease in urinary N AG activity was found 1 week after UTO. All parameters normalized afte r 6 weeks. Albuminuria increased progressively (P < 0.01) during the s tudy. Conclusion: tubular proteinuria increases during the first week following UTO in rats. The initial increase of low molecular weight pr oteins following UTO is not due to tubular damage as no parallel incre ase of urinary NAG was found. We suggest an initial tubular overperfus ion with primary urine, due to an increased single nephron glomerular filtration and overruling the reabsorption capacity of the proximal tu bules.