title: Lack of endothelial nitric oxide synthase decreases cardiomyocyte proliferation and delays cardiac maturation.
abstract: We recently demonstrated that deficiency in endothelial nitric oxide synthase (eNOS) results in congenital septal defects and postnatal heart failure. The aim of this study was to investigate the role of eNOS in cardiomyocyte proliferation and maturation during postnatal development. Cultured eNOS knockout (eNOS(-/-)) cardiomyocytes displayed fewer cells and lower bromodeoxyuridine (BrdU) incorporation in vitro compared with wild-type (WT) cardiomyocytes (P < 0.05). Treatment with the nitric oxide (NO) donor diethylenetriamine NONOate increased BrdU incorporation and cell counts in eNOS(-/-) cardiomyocytes (P < 0.05). Inhibition of nitric oxide synthase activity using N(G)-nitro-L-arginine methyl ester decreased the level of BrdU incorporation and cell counts in WT cardiomyocytes (P < 0.05). Vascular endothelial growth factor (VEGF) increased the level of BrdU incorporation in cultured WT cardiomyocytes in a dose- and time-dependent manner (P < 0.05). Conversely, VEGF did not alter BrdU incorporation in eNOS(-/-) cardiomyocytes (P = not significant). Furthermore, deficiency in eNOS significantly decreased BrdU labeling indexes in neonatal hearts in vivo. Although WT hearts displayed a rapid decrease in atrial natriuretic peptide (ANP) expression in the first week of neonatal life, ANP expression in eNOS(-/-) hearts remain elevated. Our study demonstrated that NO production from eNOS is necessary for postnatal cardiomyocyte proliferation and maturation, suggesting that eNOS plays an important role during postnatal heart development.
authors.affiliation: Cardiology Research Laboratory, Departments of Medicine and Physiology and Pharmacology, London Health Sciences Center, University of Western Ontario, London, Ontario, Canada.
authors.forename: Erin
authors.initials: E
authors.lastname: Lepic
authors.forename: Dylan
authors.initials: D
authors.lastname: Burger
authors.forename: Xiangru
authors.initials: X
authors.lastname: Lu
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.forename: Qingping
authors.initials: Q
authors.lastname: Feng
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006321:Heart / Q000254:growth & development*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D024723:Ventricular Myosins / Q000235:genetics / Q000378:metabolism
chemical_list: D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D052250:Nitric Oxide Synthase Type III; D024723:Ventricular Myosins; D018995:Myosin Heavy Chains; D001973:Bromodeoxyuridine