Neonatal angiotensin-converting enzyme inhibition in the rat induces persistent abnormalities in renal function and histology.

Recently, we reported that neonatal blockade of the renin-angiotensin system in the rat produces irreversible abnormalities in renal histology associated with increased diuresis. In the present study, we assessed the long-term consequences of neonatal angiotensin-converting enzyme inhibition on renal function. Rats were injected with 10 mg.kg-1.d-1 enalapril or vehicle from day 3 to day 24 after birth. Urine concentrating ability, renal function, and renal histology were assessed in 16-week-old rats. There was a twofold increase in diuresis and water intake in enalapril-treated rats throughout the study course. Urine osmolality after 24 hours of water deprivation was 1008 +/- 108 and 2549 +/- 48 mOsm.kg-1 (P < .05) in enalapril- and vehicle-treated rats, respectively. Glomerular filtration rate (0.54 +/- 0.03 versus 0.75 +/- 0.06 mL.min-1x100 g body wt-1, P < .05) and effective renal plasma flow (1.76 +/- 0.09 versus 2.19 +/- 0.14 mL.min-1x100 g body wt-1, P < .05) were reduced in neonatally enalapril-treated versus control rats. Absolute and fractional urinary sodium excretion values were elevated (P < .05) in enalapril-treated rats. Semiquantitative assessment of renal histology demonstrated statistically significant degrees of papillary atrophy, interstitial fibrosis and inflammation, tubular atrophy and dilatation, and focal glomerulosclerosis in neonatally enalapril-treated rats. In conclusion, neonatal angiotensin-converting enzyme inhibition in the rat produces irreversible alterations in renal function and morphology, demonstrating the importance of an intact renin-angiotensin system neonatally for normal renal development.