[Show abstract][Hide abstract] ABSTRACT: Chronic reduction in substrate delivery to the fetus may induce redistribution of fetal cardiac output to maintain nutrient delivery to vital organs, including the brain. Reduced vasoconstriction, in conjunction with increased local synthesis of nitric oxide may contribute to "brain sparing." The authors hypothesized that maternal undernutrition would reduce vasoconstrictor responses in fetal carotid arteries due to increased nitric oxide. Timed pregnant Sprague-Dawley rats were randomized on day 0 of pregnancy to control (C) or nutrient restricted (NR) diet. Dams were killed on day 20 of pregnancy. Fetal carotid artery responses were assessed using a pressurized myograph system. Fetal body weight was reduced by NR diet. In NR fetuses, liver, lung, kidney, and heart weights were lower, whereas proportional brain weight was greater. Carotid artery constriction to endothelin-1 was similar in both groups; however, phenylephrine-induced constriction was decreased in NR arteries. Arteries from control fetuses constricted in response to increasing concentrations of L-NAME, whereas arteries from NR did not. There was also no effect of L-NAME on constriction to phenylephrine in arteries from NR fetuses. Our study indicates that the reduced carotid artery vasoconstriction to phenylephrine in NR fetuses, which is consistent with the maintenance of fetal brain blood flow, was not mediated by enhanced nitric oxide. Reduced phenylephrine but not endothelin-1-induced constriction suggests specific effects on adrenergic carotid artery function, which may implicate this pathway in the vascular adaptation to fetal undernutrition.
Pediatric Research 12/2005; 58(5):840-4. · 2.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In response to reduced oxygen or nutrient supply, the fetus may redistribute cardiac output to conserve brain and heart growth, at the expense of the peripheral tissues; however, it is not known whether alterations in vascular function are maintained after birth or whether reduced fetal oxygen versus nutrient supply produces distinct effects. Using a pressure myograph, we examined isolated carotid and femoral artery responses to phenylephrine and endothelin-1 in neonatal rats, after either reduced maternal oxygen or global nutrient restriction during late gestation. Timed-pregnant Sprague-Dawley rats were randomly assigned to control (n = 10), hypoxia (12% O2, n = 9), or nutrient restriction (NR, 40% of control diet, n = 7) protocol and treated from day 15-21 of pregnancy. Pups were collected 3-12 h after birth. Neonatal weights (P < 0.001) and relative liver weights (P < 0.001) were lower in hypoxia and nutrient restriction treatments compared with control, while relative heart weights were greater in the hypoxia than in the control or nutrient restriction groups (P < 0.01). Constriction to phenylephrine was reduced in carotid arteries from the hypoxia and nutrient restriction groups compared with control (P < 0.001), while the femoral artery response was greater in hypoxia-treated neonates compared with control or nutrient-restricted neonates (P < 0.01). Only the hypoxia reduced carotid responses to endothelin-1, while no differences were observed in the endothelin-1 responses in femoral arteries. Maternal hypoxia and maternal nutrient restriction produced distinct effects on heart growth and neonatal vascular function, suggesting that regional changes in cardiovascular function after poor fetal growth are dependent on the nature of the insult in utero.
[Show abstract][Hide abstract] ABSTRACT: The harlequin color change is an unusual cutaneous phenomenon observed in newborn infants as transient, benign episodes of a sharply demarcated erythema on half of the infant, with simultaneous contralateral blanching. In this report, two newborns with congenital heart anomalies demonstrated the harlequin color change, one whose skin findings showed a course related to the dose of systemic prostaglandin E1, suggesting a possible association. The benign, self-limited nature of the color change mandates that prostaglandin E1 not be discontinued for this reason. The entity is likely more common than the paucity of reports in the world literature suggests, and all physicians should recognize its graphic appearance to avoid unnecessary exposure to agents in an effort to treat it.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to determine if maternal undernutrition during pregnancy altered myogenic tone in small radial uterine arteries.
Myogenic tone of radial uterine arteries was studied from late pregnant rats (day 20) that were fed either ad libitum or globally restricted diet (moderately severe dietary restriction) throughout pregnancy.
Myogenic tone was enhanced in the radial uterine arteries from the diet-restricted compared with the ad libitum group. Nitric oxide synthase inhibition enhanced myogenic tone in the arteries from the ad libitum group only. Prostaglandin H synthase inhibition had no effect on myogenic tone in either group.
Diet restriction during pregnancy enhances myogenic tone in the radial uterine arteries partly as a result of impairment of the nitric oxide synthase pathway. Enhanced myogenic tone in turn may reduce uteroplacental blood flow and, thus, contribute to reduced birth weight, and lead to effects of fetal programming in utero that can have long-term consequences into adulthood.
American Journal of Obstetrics and Gynecology 08/2004; 191(1):334-9. · 3.88 Impact Factor