title: Genetic contribution of the endothelial constitutive nitric oxide synthase gene to plasma nitric oxide levels.
abstract: Nitric oxide (NO) has an important physiological role in regulating vascular tone and is also relevant to many pathological processes including hypertension and atherosclerosis. Endothelial constitutive nitric oxide synthase (ecNOS) is the key enzyme in determining basal vascular wall NO production. We used a combination of maximum-likelihood-based statistical genetic methods to explore the contributions of the ecNOS gene and other unmeasured genes to basal NO production measured by its metabolites (NOx: nitrite and nitrate) in 428 members of 108 nuclear families. Our initial quantitative genetic analysis estimated that approximately 30% of the variance in fasting NOx levels is due to genes (chi 2(1) = 16.04, P = .000062). Complex segregation analysis detected the effects of both a single locus and residual polygenes on NOx levels, and measured genotype analysis showed that plasma NOx levels in those homozygous for the rare allele (64.9 +/- 7.8 mumol/L) were significantly higher (P = .000242) than those homozygous for the common allele (30.2 +/- 3.1 mumol/L). The results of the variance component linkage analysis were consistent with linkage of a quantitative trait locus in or near the ecNOS gene to variation in plasma NOx levels (P = .0066). While many environmental factors have been shown to alter transiently plasma NOx levels, our study is the first to identify a substantial effect of the ecNOS locus on the variance of plasma NOx, i.e. basal NO production. This finding may be relevant to atherogenesis and NO-related disorders.
authors.affiliation: Department of Cardiovascular Medicine, Prince Henry Hospital, Little Bay, NSW, Australia. x.l.wang@unsw.edu.au
authors.forename: X L
authors.initials: XL
authors.lastname: Wang
authors.forename: M C
authors.initials: MC
authors.lastname: Mahaney
authors.forename: A S
authors.initials: AS
authors.lastname: Sim
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Blangero
authors.forename: L
authors.initials: L
authors.lastname: Almasy
authors.forename: R B
authors.initials: RB
authors.lastname: Badenhop
authors.forename: D E
authors.initials: DE
authors.lastname: Wilcken
mesh_terms: D000293:Adolescent; D000328:Adult; D001161:Arteriosclerosis / Q000453:epidemiology / Q000235:genetics; D002648:Child; D015331:Cohort Studies; D004198:Disease Susceptibility; D004730:Endothelium, Vascular / Q000201:enzymology*; D004790:Enzyme Induction; D005215:Fasting / Q000097:blood; D005260:Female; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D019655:Quantitative Trait, Heritable; D012307:Risk Factors
chemical_list: D007527:Isoenzymes; D009569:Nitric Oxide; C496320:NOS1 protein, human; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III