Postnatal renal development of rats from mothers that received increased sodium intake.

The newborn rat kidney is not fully developed until approximately 12 days after birth. Several lines of evidence suggest that angiotensin II (AII) participates in the postnatal development of the kidney. The aim of the present study was to analyze proliferating cell nuclear antigen (PCNA), fibronectin, alpha-smooth muscle-actin (alpha-SM-actin), and AII expression in renal cortex during development in rats born to mothers that received a normal (control) or increased (experimental) sodium intake during pregnancy. Ninety Wistar rats aged 1, 7, 15, and 30 days from the control and experimental groups were killed and the kidneys removed for histological and immunohistochemical studies. The results showed higher fibronectin, alpha-SM-actin, PCNA, and AII expression in the glomerular and tubulointerstitial areas of the renal cortex of 1- and 7-day-old animals, which decreased with renal development. The animals from the experimental group showed at 1 day of age a decrease in alpha-SM-actin, fibronectin, PCNA, and AII expression compared with controls of the same age ( P<0.05). In conclusion, our data show that increased sodium intake during pregnancy induces a reduction of alpha-SM-actin, fibronectin, and PCNA expression in the renal cortex tubulointerstitium and glomeruli of neonatal rats. These alterations may be related to the decrease of AII expression also observed in the renal cortex from these animals.