Captopril Reduces Interstitial Renal Fibrosis and Preserves More Normal Renal Tubules in Neonatal Dogs with Partial Urethral Obstruction: a Preliminary Study

Purpose: Chronic renal damage due to tubulointerstitial fibrosis is one of several complications of posterior urethral valves in a significant number of children. As activation of the renin-angiotensin system plays an important role in this injury, we conducted this study to investigate whether administration of captopril reduced renal fibrosis in an experimental model using partial urethral obstruction (PUO) in neonatal dogs.

Material And Methods: Experimental PUO was induced in all pups. These animals were then divided into two groups: in the first group (experimental), captopril 35 mg/kg/day, dissolved in drinking water, was administered for 6 weeks. The second group (positive control) did not receive any treatment. After 6 weeks all dogs underwent left nephrectomy. Volume fraction and absolute volume of the histological kidney parameters, i.e., normal glomerulus, normal tubule, vessels, degenerated glomerulus, degenerated tubule, fibrous tissue, were estimated using modern unbiased stereological methods.

Results: The absolute volume of interstitial fibrosis was lower in the experimental group (PUO with captopril treatment) (approximately 73%; p < 0.008) in comparison with positive control animals (PUO with no treatment). The mean absolute volume of normal tubules in the experimental group was more than the positive control group (approximately 33%, p < 0.008). The mean absolute volume of normal and degenerated glomerulus, vessels and degenerated tubule did not show a significant difference between the two groups.

Conclusion: Administration of captopril decreases interstitial renal fibrosis and preserves renal tubules in neonatal dogs with PUO.