Intrauterine growth retardation (IUGR) was induced in Sprague-Dawley rats by partial artery ligation of one uterine horn in the mother on day 17 of gestation or by feeding the mother a 5% protein diet from day 8 of gestation. The controls were pups of the contralateral uterine horn or pups born to mothers fed a normal (22%) protein diet. The number of nephrons present at birth and the final number of nephrons in 2-week-old rats were counted throughout the entire kidney. The number of nephrons present at birth and the final number of nephrons were significantly correlated with birth weight for growth-retarded rats of both groups and their corresponding controls (P < 0.02 for the poorest correlation). Clearance experiments and morphometric studies of 2-week-old rats born to mothers with uterine artery ligation indicated that, despite a large compensatory hypertrophy of the nephrons in those animals born with a nephron deficit of about 30%, the overall renal function was impaired. We conclude that IUGR is accompanied by a nephron deficit which may not be fully compensated for within the first weeks after birth.

We conclude that vitamin A supply to the fetus is critical in determining the number of nephrons. Data available thus far on the frequency of mild VAD during pregnancy and on the long-term consequences of inborn nephron deficit highlight the clinical relevance of the present study.

Abstract-Long-term vascular and renal consequences of neonatal oxidative injury are unknown. Using a rat model, we sought to investigate whether vascular function and blood pressure are altered in adult rats exposed to hyperoxic conditions as neonates. We also questioned whether neonatal O 2 injury causes long-term renal damage, important in the pathogenesis of hypertension. Sprague-Dawley pups were kept with their mother in 80% O 2 or room air from days 3 to 10 postnatal, and blood pressure was measured (tail cuff) from weeks 7 to 15. Rats were euthanized, and vascular reactivity (ex vivo carotid rings), oxidative stress (lucigenin chemiluminescence and dihydroethidium fluorescence), microvascular density (tibialis anterior muscle), and nephron count were studied. In male and female rats exposed to O 2 as newborns, systolic and diastolic blood pressures were increased (by an average of 15 mm Hg); ex vivo, maximal vasoconstriction (both genders) and sensitivity (males only) specific to angiotensin II were increased; endotheliumdependant vasodilatation to carbachol but not to NO-donor sodium nitroprussiate was impaired; superoxide dismutase analogue prevented vascular dysfunction to angiotensin II and carbachol; vascular superoxide production was higher; and capillary density (by 30%) and number of nephrons per kidney (by 25%) were decreased. These data suggest that neonatal hyperoxia leads in the adult rat to increased blood pressure, vascular dysfunction, microvascular rarefaction, and reduced nephron number in both genders. Our findings support the hypothesis of developmental programming of adult cardiovascular and renal diseases and provide new insights into the potential role of oxidative stress in this process. Key Words: hypertension Ⅲ vascular dysfunction Ⅲ developmental origin of adult onset disease Ⅲ oxygen Ⅲ angiotensin Ⅲ microvascular rarefaction Ⅲ nephron number P remature babies, representing Ϸ8% of all births, have decreased antioxidant defenses and are exposed on birth to high oxygen (O 2 ) concentration relative to the intrauterine milieu. 1,2 This results in high O 2 -derived free radicals. Evidence in humans and animal studies indicate that premature newborns are more susceptible to oxidative tissue damage, leading to pathologies such as retinopathy of prematurity and bronchopulmonary dysplasia. 3,4 However, the long-term vascular and blood pressure consequences of neonatal hyperoxic injury are unknown.It is becoming increasingly evident that conditions early in life can influence adult diseases; however, the mechanisms are incompletely understood. 5,6 Recent data suggest that perinatal oxidative stress may be the initiating trigger in long-term programming of cardiovascular function. In a previous study, we found that cellular antioxidant glutathione is decreased in the fetus of dams fed a low-protein (LP) diet during gestation. In that model, administration of the peroxidation inhibitor lazaroid to the pregnant dam prevented elevated blood pressure, vascular dysfunction, and microvascular rar...