title: How ubiquitous is endothelial NOS?
abstract: The ability to regulate vascular tone is an essential cardiovascular control mechanism, with nitric oxide (NO) assumed to be a ubiquitous smooth muscle relaxant. However, the literature contains reports of vasoconstrictor, vasodilator and no response to nitroergic stimulation in non-mammalian vertebrates. We examined functional (branchial artery myography), structural (immunohistochemistry of skeletal muscle), proteomic (Western analysis) and genomic (RT-PCR, sequence orthologues, syntenic analysis) evidence for endothelial NO synthase (NOS3) in model and non-model fish species. A variety of nitrodilators failed to elicit any changes in vascular tone, although a dilatation to exogenous cyclic GMP was noted. NOS3 antibody staining does not localise to endothelial markers in cryosections, and gives rise to non-specific staining of Western blots. Abundant NOS2 mRNA was found in all species but NOS3 was not found in any fish, while putative orthologues are not flanked by similar genes to NOS3 in humans. We conclude that NOS3 does not exist in fish, and that previous reports of its presence may reflect use of antibodies raised against mammalian epitopes.
authors.affiliation: Centre for Cardiovascular Sciences, University of Birmingham, UK.
authors.forename: Fahima
authors.initials: F
authors.lastname: Syeda
authors.forename: David
authors.initials: D
authors.lastname: Hauton
authors.forename: Steven
authors.initials: S
authors.lastname: Young
authors.forename: Stuart
authors.initials: S
authors.lastname: Egginton
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005399:Fishes / Q000378:metabolism*; D056426:Genetic Loci / Q000235:genetics; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D016013:Likelihood Functions; D058977:Molecular Sequence Annotation; D009132:Muscles / Q000166:cytology / Q000378:metabolism; D009213:Myography; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D051381:Rats; D017208:Rats, Wistar; D026801:Synteny / Q000235:genetics
chemical_list: D052250:Nitric Oxide Synthase Type III
keywords: Capillaries; Fish; Histochemistry; Muscle; Myography; Synteny; eNOS