Chronic hypoxia increases inducible NOS-derived nitric oxide in fetal guinea pig hearts.
Intrauterine hypoxia impacts fetal growth and organ function. Inducible nitric oxide synthase (iNOS) and neuronal NOS (nNOS) expression was measured to assess the response of fetal hearts to hypoxic (HPX) stress. Pregnant guinea pigs were housed in a hypoxic chamber (10.5% O2 for 14 d, n = 17) or room air [normoxic (NMX), n = 17]. Hearts of anesthetized near-term fetuses were removed. mRNA [hypoxia-inducible factor, (HIF)-1alpha, 1beta, 2alpha, 3alpha, iNOS, and nNOS] and protein levels (HIF-1alpha, iNOS, and nNOS) of fetal cardiac left ventricles were quantified by real time polymerase chain reaction (PCR) and Western analysis, respectively. Cardiac nitrite/nitrate levels were measured in the presence/absence of L-N6-(1-iminoethyl)-lysine (L-NIL), an iNOS inhibitor, administered to pregnant sows. Hypoxia significantly increased fetal cardiac HIF-1alpha and -2alpha mRNA, HIF-1alpha protein but not HIF-3alpha or -1beta mRNA levels. Hypoxia increased both iNOS mRNA (by 5x) and protein (by 23%) levels but had no effect on nNOS levels. Nitrite/nitrate levels were increased in HPX hearts by 2.5x and decreased with L-NIL by 67 +/- 14%. Thus, up-regulation of iNOS-derived nitric oxide (NO) generation is an important mechanism by which fetal hearts respond to chronic hypoxic stress.
Thompson
Loren
L
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. lthompson1@umm.edu
Dong
Yafeng
Y
Evans
Lashauna
L
D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002908:Chronic Disease; D004195:Disease Models, Animal; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005311:Fetal Hypoxia / Q000196:embryology / Q000201:enzymology*; D005865:Gestational Age; D006168:Guinea Pigs; D006321:Heart / Q000196:embryology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology*; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D009573:Nitrites / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation; D000099162:Endothelial PAS Domain-Containing Protein 1
D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D004791:Enzyme Inhibitors; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008239:Lysine; D009566:Nitrates; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites; D012333:RNA, Messenger; D000099162:Endothelial PAS Domain-Containing Protein 1; C090663:N(6)-(1-iminoethyl)lysine