title: Lack of evidence for contribution of Glu298Asp (G894T) polymorphism of endothelial nitric oxide synthase gene to plasma nitric oxide levels.
abstract: BACKGROUND
  Both positive and negative associations between a rare allele of 27-bp repeat polymorphism in intron 4 of endothelial nitric oxide synthase and plasma nitric oxide (NO) levels were previously reported, and further, these conflicting results were suggested to be partly accounted for smoking status of subjects. However, the genetic contribution of Glu298Asp (G894T) polymorphism to plasma NO levels with respect to smoking status has not been published.
  
  
  METHODS
  In a group of 411 healthy Korean subjects aged 19-81 years, the end product of NO (NO(x): nitrite plus nitrate) as an index of plasma NO levels was measured by the Griess method. The genotypes of G894T polymorphism were determined by the banding patterns on gel electrophoresis after restriction enzyme digestion.
  
  
  RESULTS
  Comparison of plasma NO(x) levels revealed no significant differences across the genotypes and alleles of G894T polymorphism, which is independently of smoking status. However, significant differences in plasma NO(x) levels between nonsmokers and smokers were observed (P = 0.0040). Furthermore, only the common G allele was found to be responsible for these differences. Multiple regression analysis showed that the most independent contributing factor for plasma NO(x) levels was smoking (P = 0.0119) and followed by triglycerides (P = 0.0384).
  
  
  CONCLUSIONS
  Our results indicate no substantial effect of G894T polymorphism on the variance of plasma NO(x) levels in healthy Korean population.
authors.affiliation: Division of Cardiovascular Research, Department of Biomedical Sciences, National Institute of Health, 5 Nokbun-dong, Eunpyung-gu, Seoul 122-701, South Korea.
authors.forename: Jesung
authors.initials: J
authors.lastname: Moon
authors.forename: Suin
authors.initials: S
authors.lastname: Yoon
authors.forename: Eunkyung
authors.initials: E
authors.lastname: Kim
authors.forename: Chol
authors.initials: C
authors.lastname: Shin
authors.forename: Sangmee Ahn
authors.initials: SA
authors.lastname: Jo
authors.forename: Inho
authors.initials: I
authors.lastname: Jo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005838:Genotype; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052250:Nitric Oxide Synthase Type III; D020641:Polymorphism, Single Nucleotide; D012044:Regression Analysis; D012907:Smoking / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: D014280:Triglycerides; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III