Endothelial nitric oxide synthase gene haplotypes affect nitrite levels in black subjects.

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene have been associated with variations in nitric oxide (NO) formation and response to drugs in white subjects. We examined whether genetic polymorphisms (T-786C, b/a intron 4 and Glu298Asp) and haplotypes of the eNOS gene affect NO formation in 179 healthy black subjects. To assess NO formation, we measured the concentrations of nitrite in the plasma, red blood cells and whole blood. Although we found no effects of individual eNOS polymorphisms on NO formation, we found that the 'C-4b-Glu' haplotype is significantly more common in subjects with low circulating plasma and whole blood nitrite concentrations compared with subjects with high circulating nitrite concentrations (both P<0.0007). These findings reproduce previous findings in white subjects and are consistent with the idea that defining genetic markers is more important than ethnic classification, at least in terms of NO formation.

eNOS haplotype associated with hypertension in obese children and adolescents.

OBJECTIVE: The aim of our study is to investigate whether genetic polymorphisms in the endothelial nitric oxide synthase (eNOS) gene (in the promoter region T(-786)C, in exon 7 (Glu298Asp) and in intron 4 (4b/4a)) or eNOS haplotypes are associated with hypertension in obese children and adolescents. METHODS: We genotyped 175 healthy (controls), 110 normotensive obese and 73 hypertensive obese children and adolescents. Genotypes were determined by Taqman allele discrimination assay and real-time PCR, and by PCR followed by fragment separation by electrophoresis. We compared the distribution of eNOS genotypes, alleles and haplotypes in the three study groups of subjects. We have also measured whole-blood nitrite concentrations. RESULTS: The 4a4a genotype for the intron 4 polymorphism was more common in normotensive obese and hypertensive obese (P<0.01). The AspAsp genotype for Glu298Asp polymorphism was less common in normotensive obese (P<0.02). No significant differences were found in allele distributions for the three eNOS polymorphisms. However, the haplotype combining the C, 4b and Glu variants for the three polymorphisms was more common in hypertensive obese than in normotensive obese or control children and adolescents (odds ratio=2.28 and 2.79, respectively; 95% confidence interval: 1.31-4.31 and 1.39-5.64, respectively; both P<0.00625). This haplotype was not associated with significantly different nitrite concentrations (P>0.05). CONCLUSIONS: Our findings suggest that the eNOS haplotype, C b Glu, is associated with hypertension in obese children and adolescents. Further studies examining the possible interactions of eNOS haplotypes with environmental factors and other genetic markers involved in the development of obesity and its complications are warranted.

Relationship between systemic nitric oxide metabolites and cyclic GMP in healthy male volunteers.

AIM: Nitric oxide (NO) is an endogenous mediator of many physiological processes, many of which are mediated by cyclic guanosine 3',5'-monophosphate (cGMP). Much effort has been made to validate clinical markers of NO production or bioavailability. While the measurement of plasma nitrate, nitrite, and cGMP concentrations have been suggested to reflect endogenous production of NO, there is no study showing whether there is correlation between these three markers. In the present study, we investigate whether there is correlation between the plasma concentrations of nitrate, nitrite, and cGMP in a relatively homogeneous group of 141 healthy subjects. METHODS: Venous blood samples were collected from healthy male subjects and plasma aliquots were then immediately removed and stored at -70 degrees C until analysed in duplicate for their nitrite and nitrate content using ozone-based chemiluminescence assays. Plasma cGMP levels were determined by using a commercial enzyme immunoassay. RESULTS: While we found no significant correlation between plasma nitrite and nitrate concentrations (P = 0.747), or between plasma nitrate and cGMP concentrations (P = 0.221), a significant positive correlation was found between plasma cGMP and nitrite concentrations (P = 0.017, r(s) = 0.270). CONCLUSIONS: The significant correlation we found between plasma nitrite and cGMP concentrations is consistent with the notion that nitrite or cGMP concentrations in plasma may be useful clinical markers of NO formation in healthy subjects.