Maternal nutrient restriction reduces carotid artery constriction without increasing nitric oxide synthesis in the late gestation rat fetus.
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.
Campbell
Morag E
ME
Neonatal Department, Guys and St Thomas' Hospitals, London, UK, SE1 7EH.
Williams
Sarah J
SJ
Veerareddy
Sukrutha
S
Davidge
Sandra T
ST
D000818:Animals; D031204:Caloric Restriction; D002339:Carotid Arteries / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D039382:Maternal Nutritional Physiological Phenomena; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D009929:Organ Size; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester