Development of heart failure and congenital septal defects in mice lacking endothelial nitric oxide synthase.
BACKGROUND
Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an important role in the regulation of cell growth, apoptosis, and tissue perfusion. Recent studies showed that mice deficient in eNOS developed abnormal aortic bicuspid valves. The aim of the present study was to additionally investigate the role of eNOS in heart development.


RESULTS
We examined postnatal mortality, cardiac function, and septum defects in eNOS(-/-), eNOS(+/-), and wild-type mice. Postnatal mortality was significantly increased in eNOS(-/-) (85.1%) and eNOS(+/-) (38.3%) compared with wild-type mice (13.3%, P<0.001). Postmortem examination found severe pulmonary congestion with focal alveolar edema in mice deficient in eNOS. Heart shortening determined by ultrasound crystals was significantly decreased in eNOS(-/-) compared with wild-type mice (P<0.05). Congenital atrial and ventricular septal defects were found in neonatal hearts. The incidence of atrial or ventricular septal defects was significantly increased in eNOS(-/-) (75%) and eNOS(+/-) (32.4%) neonates compared with those of the wild-type mice (4.9%). At embryonic days 12.5 and 15.5, cardiomyocyte apoptosis and myocardial caspase-3 activity were increased in the myocardium of eNOS(-/-) compared with wild-type embryos (P<0.01), and increases in apoptosis persisted to neonatal stage in eNOS(-/-) mice.


CONCLUSIONS
Deficiency in eNOS results in heart failure and congenital septal defects during cardiac development, which is associated with increases in cardiomyocyte apoptosis. Our data demonstrate that eNOS plays an important role in normal heart development.
Feng
Qingping
Q
Department of Medicine, London Health Sciences Centre, London, Ontario, Canada. qfeng@uwo.ca
Song
Wei
W
Lu
Xiangru
X
Hamilton
Joel A
JA
Lei
Ming
M
Peng
Tianqing
T
Yee
Siu-Pok
SP
D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D004195:Disease Models, Animal; D006321:Heart / Q000196:embryology; D006325:Heart Atria / Q000002:abnormalities / Q000201:enzymology / Q000473:pathology; D006333:Heart Failure / Q000150:complications / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D006343:Heart Septal Defects / Q000150:complications / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D006352:Heart Ventricles / Q000002:abnormalities / Q000201:enzymology / Q000473:pathology; D006579:Heterozygote; D006720:Homozygote; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000172:deficiency* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D015996:Survival Rate
D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D020169:Caspases