eNOS genotype is without effect on circulating nitrite/nitrate level in healthy male population

Endothelial NO synthase 786T/T polymorphism increases hemorrhagic transformation after endovascular thrombectomy

BACKGROUND AND PURPOSE

This study examined whether the 786 NOS3 polymorphism is associated with the risk of hemorrhagic transformation (HT) in stroke patients with anterior large vessel occlusion (ALVO) treated using endovascular thrombectomy (EVT).

METHODS

We performed an observational cohort study that included 118 patients with ALVO who underwent EVT. HT was assessed in follow-up CT and MRI. HT and non-HT patients were compared in terms of the 786 NOS3 polymorphism, flow mediated dilation (FMD) values within 3 days after the stroke, and collateral status based on three grading scales. Demographics, vascular risk factors, additional radiological data including ASPECT score, thrombus length and infarct size, and EVT procedure and outcome variables were also included.

RESULTS

Radiological HT occurred in 55 (46.6%) patients and the 786T/T NOS3 polymorphism was associated with HT (unadjusted OR of 2.33, 95%CI: 1.05-5.20, adjusted OR of 3.14, 95%CI: 1.16-8.54). Collateral status and systemic endothelial function assessed by FMD were not mediators of this relationship as no differences were seen in the median FMD percentage values or collateral status between NOS3 genotypes.

CONCLUSIONS

Our results suggest that genetic variations affecting the NO pathway, such as the 786 NOS3 polymorphism, may contribute to individual variability in the occurrence of HT and these results support involvement of this pathway in the pathogenesis of ischemia-reperfusion injury after EVT.

Influence of NOS3 rs2070744 genotypes on hepatocellular carcinoma patients treated with lenvatinib

We investigated whether or not nitric oxide synthase 3 (NOS3) rs2070744 genotypes can affect the response for lenvatinib treatment in patients with hepatocellular carcinoma (HCC). We evaluated the relation of the NOS3 rs2070744 genotypes to the tumor response, progression-free survival (PFS), and overall survival (OS) as the response for lenvatinib. We also examined the association between fibroblast growth factor receptor (FGFR) gene polymorphisms, a potential feature of lenvatinib, and the response. There were no significant differences between the studies for either PFS or OS, even though patients with the TT genotype had a longer mean PFS (hazard ratio [HR] 0.60; p = 0.069) and mean OS (HR 0.46; p = 0.075) than those with the TC/CC genotypes. However, patients with a single-nucleotide polymorphism (SNP) combination pattern of the NOS3 rs2070744 TC/CC and FGFR4 rs351855 CT/TT genotypes had a significantly shorter mean PFS (HR 2.56; p = 0.006) and mean OS (HR 3.36; p = 0.013) than those with the other genotypes. The NOS3 rs2070744 genotypes did not influence the clinical response. However, the SNP combination pattern of the NOS3 rs2070744 and FGFR4 rs351855 genotypes may be helpful as treatment effect predictors and prognostic factors for HCC patients treated with lenvatinib.

Racial disparities in cardiovascular disease risk: mechanisms of vascular dysfunction

Cardiovascular disease (CVD) accounts for a third of all deaths in the United States making it the leading cause of morbidity and mortality. Although CVD affects individuals of all races/ethnicities, the prevalence of CVD is highest in non-Hispanic black (BL) individuals relative to other populations. The mechanism(s) responsible for elevated CVD risk in the BL population remains incompletely understood. However, impaired vascular vasodilator capacity and exaggerated vascular vasoconstrictor responsiveness are likely contributing factors, both of which are present even in young, otherwise healthy BL individuals. Within this review, we highlight some historical and recent data, collected from our laboratories, of impaired vascular function, in terms of reduced vasodilator capacity and heightened vasoconstrictor responsiveness, in the peripheral and cerebral circulations in BL individuals. We provide data that such impairments may be related to elevated oxidative stress and subsequent reduction in nitric oxide bioavailability. In addition, divergent mechanisms of impaired vasodilatory capacity between BL men and women are discussed. Finally, we propose several directions where future research is needed to fill in knowledge gaps, which will allow for better understanding of the mechanisms contributing to impaired vascular function in this population. Ultimately, this information will allow for better lifestyle and therapeutic approaches to be implemented in an effort to minimize the increased CVD burden in the BL population.

Pharmacogenetic relevance of endothelial nitric oxide synthase polymorphisms and gene interactions

Endothelial nitric oxide synthase (NOS3) is a key enzyme responsible for nitric oxide (NO) generation in the vascular endothelium. Endothelial dysfunction is characterized by reduced NO production, and is a hallmark of cardiovascular diseases. Drugs with cardiovascular action may activate NOS3 and result in NO release and vasodilation. Moreover, genetic variations affect NOS3 expression and activity, and may partially explain the variability in the responses to cardiovascular drugs. We reviewed NO signaling and genetic effects on NO formation, and the effects of NOS3 polymorphisms, haplotypes and gene-gene interactions within NO signaling pathways on the responses to cardiovascular drugs. We discuss the role of rare NOS3 variants and further gene-gene interactions analysis for the development of novel therapies for cardiovascular diseases.

Association of endothelial nitric oxide synthase (eNOS) gene polymorphisms and physical fitness levels with plasma nitrite concentrations and arterial blood pressure values in older adults

Endothelial nitric oxide synthase (eNOS) gene polymorphisms are associated with reduced eNOS activity and nitric oxide (NO) production leading to an increase in blood pressure (BP). Regular exercise is the main strategy to minimize the deleterious effects of polymorphisms. However, due to the differences that physical exercise can be performed, some controversial results are found. Therefore it seems reasonable to evaluate the training status (TS). Thus, this study aimed to investigate the association of eNOS gene haplotypes and different levels of TS on nitrite concentrations (NO2-) and BP values in older adult. 424 elderly performed the following assessments: General Functional Fitness Index (GFFI) to estimate TS, systolic and diastolic blood pressure (SBP and DBP), blood collection for analysis of NO2- and g.-786T>C, intron 4b/a (VNTR) and 894G>T polymorphisms. Multivariate logistic regression showed that NO2- was influenced by GFFI and 4b/4a Intron 4. Regarding BP, GFFI influenced SBP and DBP, and just intron 4 was associated with variations in DBP. It can be observed that GFFI affected the NO2-, SBP and DBP independently of haplotypes. Therefore, maintenance of good level of TS can overcome the negative influence of genetics factors (intron 4) by increasing NO2- concentration and decreasing BP values.

Haplotype analysis of endothelial nitric oxide synthase (NOS3) genetic variants and metabolic syndrome in healthy subjects and schizophrenia patients

Background/objectives

The frequency of metabolic syndrome (MetS) is significantly higher in schizophrenia (SCH) patients, when compared to the general populatiotin. The goal of this study was to evaluate whether genetic variants T-786C (rs2070744), G894T (rs1799983) and C774T (rs1549758) in the endothelial nitric oxide (NOS3) gene and/or their haplotypes could be associated with the risk of MetS in SCH patients or healthy subjects from Russian population.

Subjects/methods

We performed two case−control comparisons. NOS3 polymorphisms were genotyped in 70 SCH patients with MetS, 190 normal weight SCH patients, 155 MetS patients, and 100 healthy controls. MetS was defined as per the criteria proposed by the International Diabetes Federation (IDF). Anthropometric, clinical, biochemical parameters, and serum nitrite concentrations were measured in all samples. Haplotype frequency estimations and linkage disequilibrium measures were made using Haploview 4.2.

Results

The higher C allele (P = 0.009) and lower TT genotype (P = 0.008) frequencies of T-786C polymorphism were found in SCH patients with MetS compared to those in normal weight SCH patients. SCH patients with MetS who were carriers of the T-786C TT genotype had lower serum total cholesterol levels in comparison to the CC genotype (P = 0.016). Furthermore, the 774T/894T haplotype was more frequent in non-SCH individuals with MetS compared to healthy controls (P = 0.0004, odds ratio = 2.18, 95% confidence interval 1.4–3.37). Conversely, the most common haplotype 774C/894G was less frequent in MetS patients than in healthy controls (P = 0.013, odds ratio = 0.61, 95% confidence interval 0.41–0.9).

Conclusions

These results indicate that the NOS3 T-786C promoter polymorphism was closely associated with MetS risk in SCH patients. In addition, the haplotypes composed of G894T and C774T polymorphisms are associated with the MetS susceptibility in Russian population.

Age and gender differences in the influences of eNOS T-786C polymorphism on arteriosclerotic parameters in general population in Japan

OBJECTIVE

The influence of T-786C polymorphism in the promoter region of endothelial nitric oxide synthase (eNOS) on arteriosclerotic parameters by age and gender were examined.

METHODS

Brachial-ankle pulse wave velocity (baPWV), heart-rate adjusted augmentation index (AIx@75), pulse pressure (PP) and albumin-creatinine ratio (ACR) were assessed as arteriosclerotic parameters in addition to non-high-density lipoprotein cholesterol (non-HDL-C) to HDL-C (non-HDL-C/HDL-C) ratio in 1499 participants. T-786C polymorphism (rs2070744) was screened using a TaqMan allelic discrimination assay. Analyses of covariance were carried.

RESULTS

Women with the non-C allele showed significantly lower AIx@75 in participants aged <65 years and baPWV in participants aged ≥65 years than those with C allele. In contrast, men with the non-C allele showed significantly higher PP in participants aged <65 years, and higher ACR and non-HDL-C/HDL-C ratio in participants aged ≥65 years. In men on cholesterol-lowering medication, the non-C allele carriers showed significantly higher non-HDL-C compared to those in the C allele carriers.

CONCLUSIONS

eNOS T-786C polymorphism is significantly associated with arteriosclerotic parameters accompanied with age and gender differences, possibly involving antioxidative and/or endothelial signaling other than inflammatory signaling.

Influence of training status and eNOS haplotypes on plasma nitrite concentrations in normotensive older adults: a hypothesis-generating study

The purpose of this study was to evaluate the relationship between 3 eNOS gene polymorphisms and training status (TS) in affecting plasma nitrite concentration (NO2) in normotensive adults over 50 years old. Resting blood pressure (BP) was measured in all participants (n = 101). Plasma was taken to analyze: lipid profile, nitrite concentration (NO2) and lipid peroxide levels (T-BARS). Also, genomic DNA was extracted from plasma for genotyping NOS3 polymorphisms (-786T>C; 894G>T; and VNTR in intron 4). TS was determined by one-mile walk test and Functional Fitness Test Battery from AAHPERD (TS1-regular TS; TS2-good TS; and TS3-very good TS). BP was not influenced by TS, but NO2 was 15% higher in TS3 (123 ± 27 nM) compared to TS-2 (106 ± 22 nM). No differences were found in plasma NO2 in the haplotype analyses. However, the presence of the C allele (T-786C) and ASP allele (Glu298Asp) was found to enhance the correlation between TS and NO2 levels (r = 0.492 in C/4b/ASP haplotype and r = 0.855 in C/4a/ASP haplotype). This study thus identifies NOS3 polymorphism-dependent sensitivity to the effects of physical training on plasma NO2. Maintenance of good levels of training status, in carriers of C allele for T-786C polymorphism, combined with ASP allele for Glu298Asp polymorphism, may result in an increase in the NO2 plasma concentrations, which may reflect improved NO bioavailability in older adult normotensive individuals.

Effects of polymorphisms in endothelial nitric oxide synthase and folate metabolizing genes on the concentration of serum nitrate, folate, and plasma total homocysteine after folic acid supplementation: a double-blind crossover study

OBJECTIVES

A number of studies have explored the effects of dietary nitrate on human health. Nitrate in the blood can be recycled to nitric oxide, which is an essential mediator involved in many important biochemical mechanisms. Nitric oxide is also formed in the body from l-arginine by nitric oxide synthase. The aim of this study was to investigate whether genetic polymorphisms in endothelial nitric oxide synthase (eNOS) and genes involved in folate metabolism affect the concentration of serum nitrate, serum folate, and plasma total homocysteine in healthy individuals after folic acid supplementation.

METHODS

In a randomized double-blind, crossover study, participants were given either folic acid 800 μg/d (n = 52) or placebo (n = 51) for 2 wk. Wash-out period was 2 wk. Fasting blood samples were collected, DNA was extracted by salting-out method and the polymorphisms in eNOS synthase and folate genes were genotyped by polymerase chain reaction methods. Measurement of serum nitrate and plasma total homocysteine (p-tHcy) concentration was done by high-performance liquid chromatography.

RESULTS

The concentration of serum nitrate did not change in individuals after folic acid supplements (trial 1); however, the concentration of serum nitrate increased in the same individuals after placebo (P = 0.01) (trial 2). The individuals with three polymorphisms in eNOS gene had increased concentration of serum folate and decreased concentration of p-tHcy after folic acid supplementation. Among the seven polymorphisms tested in folate metabolizing genes, serum nitrate concentration was significantly decreased only in DHFR del 19 gene variant. A significant difference in the concentration of serum nitrate was detected among individuals with MTHFR C > T677 polymorphisms.

CONCLUSIONS

Polymorphisms in eNOS and folate genes affect the concentration of serum folate and p-tHcy but do not have any effect on the concentration of NO3 in healthy individuals after folic acid supplementation.

Association of plasma nitric oxide concentration and endothelial nitric oxide synthase T-786C gene polymorphism in coronary artery disease

Nitric oxide (NO) is synthesized from l-arginine by endothelium nitric oxide synthase (NOS3) and plays important roles in many physiologic and pathologic processes. NO involved in the pathogenesis of coronary atherosclerosis. In the present study we hypothesized that polymorphisms of NOS gene might be associated with increased risk of coronary artery disease (CAD) and plasma NO concentrations. The eNOS gene polymorphism was investigated in 241 unrelated CAD patients with positive coronary angiograms and 261 ages matched control subjects without a history of symptomatic CAD. The NOS3 gene polymorphisms were analyzed by RFLP. Plasma NO, lipid profile and other risk factors were also assessed. The genotype frequencies for T-786C polymorphism differed significantly between CAD patients and controls (p=0.041). The mean plasma NO(x) concentrations showed significant differences according to genotypes of T-786C polymorphism in total population only. The mean plasma NO(x) increased in those individuals that are homozygote for C allele in promoter compared with those individuals are heterozygote for this allele and homozygote for T allele in total population and Controls, but no in CAD patients. The present study provides evidences that T-786C polymorphism of the NOS3 gene is associated with CAD. T-786C polymorphism was not associated with increased plasma NO in CAD patients.

Functional VEGF haplotypes affect the susceptibility to hypertension

We examined whether vascular endothelial growth factor (VEGF) polymorphisms (C-2578A, G-1154A and G-634C) are associated with hypertension, response to antihypertensive therapy and nitric oxide (NO) formation. Substudy 1 compared the distribution of VEGF genotypes and haplotypes in 178 patients with arterial hypertension (100 whites and 78 blacks) and 186 healthy controls (115 whites and 71 blacks). Substudy 2 compared the distribution of VEGF markers in 82 patients with controlled hypertension, 89 patients with resistant hypertension and 101 normotensive (NT) patients. In substudy 3, plasma nitrite/nitrate (NOx) levels were determined (chemiluminescence assay) in 64 NT subjects and 48 hypertensive (HTN) subjects, and the distribution of VEGF markers was compared in subjects having low NOx with subjects having high NOx. Although the substudy 1 showed no differences in genotypes or allele distributions for the three VEGF polymorphisms between NT and HTN subjects, the 'C-A-G' haplotype was more common in white NT subjects than in the white HTN subjects, and the 'C-A-C' haplotype was more frequent in black and white HTN subjects than in black and white NT subjects. The substudy 2 showed similar results, with no differences between responsive and resistant HTN subjects. The substudy 3 showed that the 'C-A-G' haplotype, which had a protective effect against hypertension, was significantly more common in subjects with higher NOx concentrations than in subjects with lower NOx concentrations. VEGF haplotypes are associated with hypertension, and the haplotype associated with normotension was more common in subjects with increased NO formation, possibly offering a mechanistic clue for our findings.

Influence of Klotho genotypes on plasma NO(x) levels in South Indian population

INTRODUCTION

Despite experimental evidences of the influence of the aging suppressor gene Klotho, on the modulation of endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) production, the contribution of its variants to the phenotypic variance of plasma nitrite and nitrate (NO(x)) has not been addressed to date. In the present study, we aimed to determine the influence of two exonic variants, KL-VS and C1818T of Klotho, on circulating NO(x) levels in South Indian population.

MATERIALS AND METHODS

We genotyped the two Klotho KL-VS and C1818T variants in 429 healthy South Indians and measured their plasma NO(x) concentrations by the Griess method.

RESULTS

Genotype frequencies were compared in subjects with low and high NO(x) levels. An age-specific association of the Klotho C1818T variant was found with plasma NO(x) levels in subjects aged >40 years (p=0.027); the CC homozygotes were more prevalent in the low compared to the high plasma NO(x) group. However, the variant was not associated with plasma NO(x) levels in subjects aged≤40 years (p=0.799). The KL-VS variant did not have any influence on plasma NO(x) status (p=0.260).

CONCLUSIONS

Our results suggest that the effect of Klotho C1818T variant on levels of plasma NO(x) becomes pronounced with age probably implying the adaptive capability of Klotho alleles to meet the age-related increasing physiological load.

Endothelial nitric oxide synthase gene polymorphisms associated with susceptibility to high altitude pulmonary edema in Chinese railway construction workers at Qinghai-Tibet over 4 500 meters above sea level

OBJECTIVE

To examine whether the polymorphisms of endothelial nitric oxide synthase (eNOS) gene are associated with the susceptibility to high altitude pulmonary edema (HAPE) in Chinese railway construction workers at Qinghai-Tibet where the altitude is over 4 500 m above sea level.

METHODS

A case-control study was conducted including 149 HAPE patients in the construction workers and 160 healthy controls randomly recruited from their co-workers, matching the patients in ethnicity, age, sex, lifestyle, and working conditions. Three polymorphisms of eNOS gene, T-786C in promoter, 894G/T in exon 7, and 27bp variable number tandem repeat (VNTR) in intron 4, were genotyped using polymerase chain reaction (PCR) and confirmed with DNA sequencing.

RESULTS

The frequencies of 894T allele and heterozygous G/T of the 894G/T variant were significantly higher in HAPE patients group than in the control group (P=0.0028 and P=0.0047, respectively). However, the frequencies of the T-786C in promoter and the 27bp VNTR in intron 4 were not significantly different between the two groups. Haplotypic analysis revealed that the frequencies of two haplotypes (H3,T-T-b, b indicates 5 repeats of 27 bp VNTR; H6, C-G-a, a indicates 4 repeats of 27 bp VNTR) were significantly higher in HAPE patients (both Pü0.0001). On the contrary, the frequencies of H1 (T-G-b) and H2 (T-G-a) were lower in HAPE patients than in healthy controls (both Pü0.001).

CONCLUSIONS

Two haplotypes (T-T-b and C-G-a) may be strongly associated with susceptibility to HAPE. Compared with the individual alleles of eNOS gene, the interaction of multiple genetic markers within a haplotype may be a major determinant for the susceptibility to HAPE.

Increased circulating cell-free hemoglobin levels reduce nitric oxide bioavailability in preeclampsia

Contrasting with increased nitric oxide (NO) formation during healthy pregnancy, reduced NO bioavailability plays a role in preeclampsia. However, no study has examined whether increased NO consumption by enhanced circulating levels of cell-free hemoglobin plays a role in preeclampsia. We studied 82 pregnant women (38 healthy pregnant and 44 with preeclampsia). To assess NO bioavailability, we measured plasma and whole blood nitrite concentrations using an ozone-based chemiluminescence assay. Plasma ceruloplasmin concentrations and plasma NO consumption (pNOc) were assessed and plasma hemoglobin (pHb) concentrations were measured with a commercial immunoassay. We found lower whole blood and plasma nitrite concentrations in preeclamptic patients (-48 and -39%, respectively; both P<0.05) compared with healthy pregnant women. Plasma samples from preeclamptic women consumed 63% more NO (P=0.003) and had 53% higher pHb and 10% higher ceruloplasmin levels than those found in healthy pregnant women (P<0.01). We found significant positive correlations between pHb and pNOc (r=0.61; P<0.0001), negative correlations between pNOc and whole blood or plasma nitrite concentrations (P=0.02; r=-0.32 and P=0.01; r=-0.34, respectively), and negative correlations between pHb and whole blood or plasma nitrite concentrations (P=0.03; r=-0.36 and P=0.01; r=-0.38, respectively). These findings suggest that increased pHb levels lead to increased NO consumption and lower NO bioavailability in preeclamptic compared with healthy pregnant women.

Effects of aerobic exercise on the blood pressure, oxidative stress and eNOS gene polymorphism in pre-hypertensive older people

The polymorphisms of endothelial nitric oxide synthase (eNOS) are associated with reduced eNOS activity. Aerobic exercise training (AEX) may influence resting nitric oxide (NO) production, oxidative stress and blood pressure. The purpose of this study was to investigate the effect of AEX on the relationship among blood pressure, eNOS gene polymorphism and oxidative stress in pre-hypertensive older people. 118 pre-hypertensive subjects (59 ± 6 years) had blood samples collected after a 12 h overnight fast for assessing plasma NO metabolites (NOx) assays, thiobarbituric acid reactive substances (T-BARS) and superoxide dismutase activity (ecSOD). eNOS polymorphism (T-786C and G-894T) was done by standard PCR methods. All people were divided according to the genotype results (G1: TT/GG, G2: TT/GT + TT, G3: TC + CC/GG, G4: TC + CC/GT + TT). All parameters were measured before and after 6 months of AEX (70% of VO(2 max)). At baseline, no difference was found in systolic and diastolic blood pressure, ecSOD and T-BARS activity. Plasma NOx levels were significantly different between G1 (19 ± 1 μM) and G4 (14.2 ± 0.6 μM) and between G2 (20.1 ± 1.7 μM) and G4 (14.2 ± 0.6 μM). Therefore, reduced NOx concentration in G4 group occurred only when the polymorphisms were associated, suggesting that these results are more related to genetic factors than NO-scavenging effect. After AEX, the G4 increased NOx values (17.2 ± 1.2 μM) and decreased blood pressure. G1, G3 and G4 decreased T-BARS levels. These results suggest the AEX can modulate the NOx concentration, eNOS activity and the relationship among eNOS gene polymorphism, oxidative stress and blood pressure especially in C (T-786C) and T (G-894T) allele carriers.

A pharmacogenetics-based approach to reduce cardiovascular mortality with the prophylactic use of statins

Nitric oxide (NO) is the main endothelial-derived relaxation factor and plays a major role in cardiovascular homeostasis. This key signalling molecule is synthesised by a family of nitric oxide synthases (NOS), and the endothelial isoform (eNOS) is the most important for nitric oxide formation in the cardiovascular system. Cardiovascular drugs including statins increase eNOS expression and up-regulate NO formation, and this effect may be responsible for protective, pleiotropic effects produced by statins. However, the genetic background may also affect NO formation in the cardiovascular system, and recent studies have shown that genetic polymorphisms in the eNOS gene modify endogenous NO formation and the risk of developing cardiovascular diseases. For example, cases with the CC genotype for the T(-786)C polymorphism in the eNOS gene are at increased cardiovascular risk when compared with those with the TT genotype. Interestingly, pharmacogenetic studies have recently indicated that atorvastatin improves NO formation more clearly in these individuals. However, it is not known whether this polymorphism really increases cardiovascular morbidity and mortality, and whether atorvastatin or other statins attenuate the morbidity and mortality rates in cases with the CC genotype. If proved true, then statins-induced up-regulation of eNOS and increased NO formation could compensate for a genetic 'disadvantage' in cases with the CC genotype. This could be a significant advance in the prevention of cardiovascular events. It is necessary although to validate this hypothesis with clinical trials which will require a long follow-up to assess relevant clinical events and not only surrogate biomarkers.

eNOS T-786C polymorphism affects atorvastatin-induced changes in erythrocyte membrane fluidity

PURPOSE

Statins have pleiotropic effects, including endothelial nitric oxide synthase (eNOS) upregulation and increased nitric oxide formation, which can be modulated by a genetic polymorphism in the promoter region of the eNOS gene (T-786C). Here, we report our investigation of whether this polymorphism modulates the effects of atorvastatin on the fluidity of erythrocyte membranes.

METHODS

We genotyped 200 healthy subjects (males, 18-60 years of age) and then randomly selected 15 of these with the TT genotype and 15 with the CC genotype to receive placebo or atorvastatin (10 mg/day oral administration) for 14 days. Cell membrane fluidity was evaluated by electron paramagnetic resonance (EPR) and spin-labeling method. The EPR spectra were registered on a VARIAN-E4 spectrometer. Thiobarbituric acid-reactive species (TBA-RS) and plasma membrane cholesterol were determined in the erythrocytes.

RESULTS

Atorvastatin reduced membrane fluidity in CC subjects (P < 0.05) but not in those with the TT genotype (P > 0.05). While no significant differences were found in plasma membrane cholesterol concentrations, higher TBA-RS concentrations were found in the CC subjects than in the TT subjects (P < 0.05).

CONCLUSIONS

These findings suggest that a short treatment with atorvastatin is disadvantageous to subjects with the CC genotype for the T-786C polymorphism compared to those with TT genotype, at least in terms of the hemorheological properties of erythrocytes.

Enhanced concentrations of relevant markers of nitric oxide formation after exercise training in patients with metabolic syndrome

Metabolic syndrome (MetS) denotes a clustering of risk factors that may affect nitric oxide (NO) bioavailability and predispose to cardiovascular diseases, which are delayed by exercise training. However, no previous study has examined how MetS affects markers of NO formation, and whether exercise training increases NO formation in MetS patients. Here, we tested these two hypotheses. We studied 48 sedentary individuals: 20 healthy controls and 28 MetS patients. Eighteen MetS patients were subjected to a 3-month exercise training (E+group), while the remaining 10 MetS patients remained sedentary (E-group). The plasma concentrations of nitrite, cGMP, and ADMA (asymmetrical dimethylarginine; an endogenous nitric oxide synthase inhibitor), and the whole blood nitrite concentrations were determined at baseline and after exercise training using an ozone-based chemiluminescence assay, and commercial enzyme immunoassays. Thiobarbituric acid reactive species (TBA-RS) were measured in the plasma to assess oxidative stress using a fluorometric method. We found that, compared with healthy subjects, patients with MetS have lower concentrations of markers of NO formation, including whole blood nitrite, plasma nitrite, and plasma cGMP, and increased oxidative stress (all P<0.05). Exercise training increased the concentrations of whole blood nitrite and cGMP, and decreased both oxidative stress and the circulating concentrations of ADMA (both P<0.05). These findings show clinical evidence for lower endogenous NO formation in patients with MetS, and for improvements in NO formation associated with exercise training in MetS patients.

Nitric Oxide Formation Is Inversely Related to Serum Levels of Antiangiogenic Factors Soluble Fms-Like Tyrosine Kinase-1 and Soluble Endogline in Preeclampsia

Deficient NO formation has been implicated in hypertensive disorders of pregnancy. However, no previous study has compared the circulating nitrite concentrations in healthy pregnant women with those found in hypertensive disorders of pregnancy. Moreover, 2 antiangiogenic factors produced in the placenta (soluble fms-like tyrosine kinase-1 and soluble endogline) may affect NO formation during pregnancy. Here, we hypothesized that lower concentrations of markers of NO formation exist in hypertensive disorders of pregnancy and that inverse relationships exist between these markers and soluble fms-like tyrosine kinase-1 or soluble endogline. In this cross-sectional study, we compared 58 healthy pregnant women with 56 gestational hypertensive subjects and 45 preeclamptic patients. We measured plasma and whole blood nitrite concentrations using an ozone-based chemiluminescence assay and serum soluble fms-like tyrosine kinase-1 and soluble endogline concentrations using enzyme immunoassays. Whole blood nitrite levels were significantly lower in gestational hypertensive subjects and preeclamptic patients (−36% and −58%, respectively; both P <0.05) compared with healthy pregnant women. The plasma nitrite levels were ≈37% lower in both groups with hypertensive disorders of pregnancy compared with the group with normotensive pregnancies (both P <0.05). As expected, we found higher circulating soluble fms-like tyrosine kinase-1 and soluble endogline concentrations in preeclampsia compared with gestational hypertensive subjects or with healthy pregnancies (both P <0.05). We found negative correlations between antiangiogenic factors and plasma or whole blood nitrite concentrations (Spearman’s r from −0.175 to −0.226; all P <0.05). Our results show clinical evidence for impaired NO formation in preeclampsia or gestational hypertension. The negative correlations between markers of NO formation and antiangiogenic factors in preeclamptic patients suggest an inhibitory effect for these factors on NO formation.

The association of endothelial nitric oxide synthase G894T polymorphism with C-reactive protein level and metabolic syndrome in a Chinese study group

Some studies have reported a possible relationship between endothelial nitric oxide synthase (eNOS) and metabolic syndrome (MS), which is associated with an increased risk for cardiovascular disease. A recent meta-analysis study found the eNOS G894T polymorphism to be associated with ischemic heart disease. Here, we examine the association of eNOS G894T polymorphism with MS in a Chinese population (n = 397). The eNOS T+ (TT and GT) genotypes (56.92% vs 38.86%; odds ratio, 2.08; 95% confidence interval, 1.21-3.56; P = .007) and T allele (33.08% vs 23.34%; odds ratio, 1.62; 95% confidence interval, 1.08-2.44; P = .019) were significantly more frequent in subjects who had MS. Furthermore, subjects with eNOS T+ genotypes had significantly higher plasma C-reactive protein levels as compared with GG subjects (P = .004). This study shows that, in a Chinese population, eNOS G894T polymorphism is associated with an elevated C-reactive protein level and MS.

Haplotype analysis of the endothelial nitric oxide synthase gene in asthma

Nitric oxide (NO) is an important mediator of physiologic processes in the airways. Evidence exists that genetic factors affect NO formation and contribute to the pathophysiology of asthma. The aims of this study were to determine the endothelial NO synthase (eNOS) haplotypes in Czech asthmatics and control subjects and examine their relation to asthma. We analyzed a total of six polymorphisms. Two SNPs in the promoter (C-786T and C-691T), two variants in the introns (27-bp repeat in intron 4 and G11T in intron 23), and two others in the exons (C774T in exon 6 and G894T in exon 7) were genotyped in 610 subjects (asthma, n = 294; healthy controls, n = 316), and a case-control association study was conducted. No significant differences in allele or genotype frequencies for individual polymorphisms were observed between patients with asthma and controls after correction for multiple comparisons. Nevertheless, a G to T exchange in intron 23 was related with specific sensitization for feather (p = 0.008, p(corr) < 0.05). However, the common haplotype -786T/-691C/27-bp 5 repeat variant/774C/894G/11T was associated with lower risk of asthma (p = 0.001, p(corr) < 0.05, odds ratio = 0.58, 95% confidence interval = 0.46-0.73). These findings suggest that endothelial NOS variants may be one of the factors participating in protection or susceptibility to asthma in our population.

Inverse relationship between markers of nitric oxide formation and plasma matrix metalloproteinase-9 levels in healthy volunteers

BACKGROUND

Nitric oxide (NO) is a major regulator of cardiovascular homeostasis and has anti-atherogenic properties. Reduced NO formation is associated with endothelial dysfunction and with cardiovascular risk factors. Although NO downregulates the expression and activity of the pro-atherogenic enzyme matrix metalloproteinase-9 (MMP-9), no previous clinical study has examined whether endogenous NO formation is inversely associated with the circulating levels of pro-MMP-9, which are associated with cardiovascular events. We examined this hypothesis in 175 healthy male subjects who were non-smokers.

METHODS

To assess NO bioavailability, the plasma concentrations of nitrite, nitrate, and cGMP were determined using an ozone-based chemiluminescence assay and an enzyme immunoassay. Pro-MMP-9 and pro-MMP-2 levels were measured in plasma samples by gelatin zymography.

RESULTS

We found significant negative correlations between pro-MMP-9 levels and plasma nitrite (P=0.035, rs= -0.159), nitrate (P=0.040, rs= -0.158), and cGMP (P=0.011, rs= -0.189) concentrations. However, no significant correlations were found between pro-MMP-2 levels and the plasma concentrations of markers of NO bioavailability (all P>0.05).

CONCLUSIONS

There is an inverse relationship between markers of NO formation and plasma MMP-9 levels. This finding may shed some light on the possible mechanisms involved in the increased cardiovascular risk of apparently healthy subjects with low NO bioavailability or high circulating levels of pro-MMP-9.

Racial differences in nitric oxide-dependent vasorelaxation

Along with the growing heterogeneity of the American population, ethnic/racial disparity is becoming a clear health issue in the United States. The awareness of ethnic/racial disparities has been growing because of considerable data gathered from recent clinical and epidemiological studies. These studies have highlighted the importance of addressing these differences in the diagnosis and treatment of various diseases potentially according to race. It is becoming particularly clear that there is a 2- to 3-fold racial difference in certain cardiovascular diseases (eg, preeclampsia) associated with dysfunctional nitric oxide-mediated vasodilation. In this review, the authors summarize the current literature on racial disparities in nitric oxide-mediated vasodilation in relation to cardiovascular health with an emphasis on vascular nitric oxide bioavailability as a balance between production via endothelial nitric oxide synthase and degradation through reactive oxygen species. The major hypotheses postulated on the biological basis of these differences are also highlighted.

Endothelial nitric oxide synthase gene: prospects for treatment of heart disease

Nitric oxide functions as a signaling molecule with a well-established role in vascular homeostasis. It is synthesized from the oxidation of L-arginine by the enzyme, endothelial nitric oxide synthase (eNOS). The eNOS gene has a number of polymorphic sites, including SNPs, dinucleotide repeats and variable number tandem repeat sequences, and the opportunity exists to investigate polymorphic functional correlates as well as disease-specific associations, especially in cardiovascular disease, including coronary artery disease, and its most severe consequence, myocardial infarction. A number of clinical and functional correlative studies involving eNOS polymorphisms have been reported and are presented. The promise and complexity of pharmacogenetics is illustrated using eNOS as an example because of its relationship with cardiovascular biology and pathology. In this review, we will discuss the impact of nitric oxide, eNOS, genetic regulation, clinical investigation and, ultimately, prospects for treatment of heart disease.

Endothelial nitric oxide synthase haplotypes are related to blood pressure elevation, but not to resistance to antihypertensive drug therapy

OBJECTIVES

Most hypertensive patients require two or more drugs to control arterial blood pressure effectively. Although endothelial nitric oxide synthase (eNOS) haplotypes have been associated with hypertension, it is unknown whether eNOS genotypes/haplotypes are associated with resistance to antihypertensive therapy.

METHODS

We studied the distribution of three eNOS genetic polymorphisms: single nucleotide polymorphisms in the promoter region (T(-786)C), and in exon 7 (Glu298Asp), and a variable number of tandem repeats in intron 4 (b/a). Genotypes were determined for 111 normotensive controls (NT), 116 hypertensive individuals who were well controlled (HT), and 100 hypertensive individuals who were resistant to conventional antihypertensive therapy (RHT). We also compared the distribution of eNOS haplotypes in the three groups of subjects.

RESULTS

No differences were found in genotype or allele distribution among the three groups (all P > 0.05). Conversely, the 'C Glu b' haplotype was more commonly found in the NT than in the HT or RHT groups (21 versus 8 and 7%, respectively; both P < 0.00625). In addition, the 'C Asp b' haplotype was more commonly found in the HT or RHT groups than in the NT group (22 and 20%, respectively, versus 8%; both P < 0.00625). The distribution of eNOS haplotypes was not significantly different in the HT and RHT groups (P > 0.05).

CONCLUSIONS

Whereas our findings suggest a protective effect for the 'C Glu b' haplotype against hypertension and that the 'C Asp b' haplotype increases the susceptibility to hypertension, our results suggest that eNOS haplotypes are not associated with resistance to antihypertensive therapy.

Modulation of nitric oxide formation by endothelial nitric oxide synthase gene haplotypes

Nitric oxide (NO) is a major regulator of the cardiovascular system. However, the effects of endothelial nitric oxide synthase (eNOS) gene polymorphisms or haplotypes on the circulating concentrations of nitrite (a sensitive marker of NO formation) and cGMP are unknown. Here we examined the effects of eNOS polymorphisms in the promoter region (T-786C), in exon 7 (Glu298Asp), and in intron 4 (4b/4a) and eNOS haplotypes on the plasma levels of nitrite and cGMP. We hypothesized that eNOS haplotypes could have a major impact on NO formation. We genotyped 142 healthy subjects by PCR-RFLP. To assess NO formation, the plasma concentrations of nitrite and cGMP were determined using an ozone-based chemiluminescence assay and an enzyme immunoassay. Haplotypes were inferred using the PHASE 2.1 program. No significant differences were found in age, body mass index, systolic and diastolic arterial blood pressure, heart rate, total cholesterol, triglycerides, cGMP, or nitrite among the genotype groups for the three polymorphisms studied here (all p>0.05). Interestingly, the C-4b-Glu haplotype was associated with lower plasma nitrite concentrations than those found in the other haplotype groups (p<0.05), but not with different cGMP levels (p>0.05). These findings suggest that eNOS gene variants combined within a specific haplotype modulate NO formation, although individual eNOS polymorphisms probably do not have major effects.

Clinical evidence for lead-induced inhibition of nitric oxide formation

Lead exposure has been associated with increased cardiovascular risk, which may result, at least in part, from lead-induced increases in oxidative stress and depressed nitric oxide (NO) availability. However, no previous clinical study has examined whether lead exposure is associated with significant effects on biomarkers of NO activity (plasma nitrites, nitrates, and cyclic guanosine 3',5'-monophosphate; cGMP). We investigated whether there is an association between the circulating concentrations of nitrites, nitrates, and cGMP and the concentrations of lead in whole blood (B-Pb) or plasma (P-Pb) from 62 lead-exposed subjects (30 men and 32 women). P-Pb was determined by inductively coupled plasma mass spectrometry and B-Pb by graphite furnace atomic absorption spectrometry. Plasma nitrite and nitrate concentrations were measured using an ozone-based chemiluminescence assay. Plasma cGMP concentrations were measured using a commercial enzyme immunoassay. We found a negative correlation between plasma nitrite and B-Pb concentrations (r = -0.358; P = 0.004), and between plasma nitrite and P-Pb concentrations (r = -0.264; P = 0.038), thus suggesting increased inhibition of NO formation with increasing B-Pb or P-Pb concentrations. However, no significant correlations were found between plasma nitrate or cGMP and B-Pb or P-Pb concentrations (all P > 0.05). These findings suggest a significant inhibitory effect of lead exposure on NO formation and provide clinical evidence for a biological mechanism possibly involved the association between lead exposure and increased cardiovascular risk.

Influence of eNOS haplotypes on the plasma nitric oxide products concentrations in hypertensive and type 2 diabetes mellitus patients

Endothelial nitric oxide synthase (eNOS) haplotypes are associated with hypertension (HT) in patients with or without type 2 diabetes mellitus (T2DM). We evaluated the association of eNOS genotypes/haplotypes with the plasma concentrations of nitrite/nitrate (NO(x)), which are products of nitric oxide in HT, T2DM, and T2DM+HT patients. We studied eNOS polymorphisms in the promoter region (T-786C), in exon 7 (Glu298Asp), and in intron 4 (b/a) in 98 controls, 68 patients with HT, 66 patients with T2DM, and 86 patients with T2DM+HT. NO(x) concentrations were assessed using a chemiluminescence assay. No differences were found in genotype/allele distribution among groups. Genotypes were not associated with NO(x) concentrations. The "C-Glu-b" haplotype was more common in controls than in HT/T2DM+HT groups (21% versus 9/5%, respectively, P<0.006). This haplotype was more common in HT and T2DM+HT groups among subjects with high (82+/-38 and 90+/-33 microM, respectively) than with low (35+/-7 and 34+/-7 microM, respectively) NO(x) concentrations. Conversely, the "C-Asp-b" haplotype was more common in HT/T2DM+HT groups than healthy (21/21% versus 10%, respectively, P<0.006). The haplotype associated with lower risk of developing hypertension is also associated with higher NO(x) levels among hypertensives. Conversely, the haplotype increasing the risk of developing hypertension is associated with lower NO(x) levels in hypertensives.

Endothelial Nitric Oxide Synthase Haplotypes Are Associated with Features of Metabolic Syndrome

Background: The metabolic syndrome, a cluster of several metabolic disorders, is increasingly being recognized as a risk factor for cardiovascular disease. Endothelium-derived nitric oxide facilitates skeletal muscle glucose uptake, and data from animal models indicate that endothelial nitric oxide synthase (eNOS) gene–null mice present with a phenotype of insulin resistance, hypertension, and hypertriglyceridemia, much like that observed in humans with metabolic syndrome. We used haplotype tagging single nucleotide polymorphisms (htSNPs) to investigate the role of genetic variation in the eNOS gene (NOS3) in metabolic syndrome in humans.

Methods: We recruited 738 unrelated persons from a cross-sectional population-based epidemiological survey in the province of Segovia in Central Spain (Castille). Metabolic syndrome was defined according to the recently modified National Cholesterol Education Program Adult Treatment Panel III guidelines.

Results: Haplotype analysis showed a statistically significant association between some NOS3 gene variants and features of metabolic syndrome. Relative to the most common haplotype, 121, the haplotype 212 was associated with an increased odds ratio (OR) for metabolic syndrome [OR = 1.81, 95% confidence interval (CI) 1.15–2.84], and for decreased HDL-cholesterol concentrations (OR 1.52, 95% CI 1.01–2.29), and with increased mean values for the homeostasis model assessment of insulin resistance (P = 0.043), and triglycerides (P = 0.026).

Conclusions: Our results suggest that genetic variation at the eNOS locus is associated with features of metabolic syndrome, and might represent a new genetic susceptibility component for insulin resistance, hypertriglyceridemia, and low HDL-cholesterol concentrations.

Endothelial nitric oxide synthase genotype and haplotype are not associated with diabetic retinopathy in diabetes type 2 patients

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene have been associated with the development of diabetic retinopathy (DR) in patients with type 1 diabetes mellitus (T1DM), but not with T2DM. However, no previous study has analyzed combinations of genetic markers (haplotypes), which can be more informative. We studied three eNOS genetic polymorphisms: a single nucleotide polymorphism in the promoter region (T(-786)C), in exon 7 (Glu298Asp), and a variable number of tandem repeats in intron 4 (b/a) in 103 healthy controls, and in 170 patients with T2DM (without DR, N=114; with DR, N=56). We also examined the association of eNOS gene haplotypes with T2DM and with DR. No differences were found in the frequencies of genotypes and alleles of the three polymorphisms among the three groups of subjects. However, the "C-Glu-b" haplotype was more common in healthy controls (24%) than in T2DM patients (7%) (P=0.0001). Finally, no significant difference in the distribution of eNOS haplotypes frequencies was found when T2DM patients with or without DR were compared (P=0.7372). These findings suggest no association between DR and individual eNOS haplotypes in T2DM patients. The "C-Glu-b" haplotype, however, may have a protective effect against T2DM. Further studies should be conducted to address the molecular basis for such an effect.

eNOS gene T-786C polymorphism modulates atorvastatin-induced increase in blood nitrite

Statins inhibit cholesterol synthesis and produce pleiotropic, cholesterol-independent effects including endothelial NO synthase (eNOS) stimulation and increased expression. However, a functional polymorphism in the promoter of the eNOS gene (T-786C) reduces its activity and could modulate the response to statins. Here, we examined whether this polymorphism modulates the effects of atorvastatin on the plasma levels of markers of NO formation and oxidative stress. We genotyped 200 healthy subjects for this polymorphism, and 15 subjects with the TT genotype and 15 with the CC genotype were selected to receive placebo or atorvastatin 10 mg/day po for 14 days. To assess NO bioavailability, the plasma concentrations of nitrate, nitrite, and cGMP and the whole blood nitrite concentrations were determined after placebo or atorvastatin using an ozone-based chemiluminescence assay and an enzyme immunoassay. Thiobarbituric acid-reactive species (TBA-RS) were measured in the plasma to assess oxidative stress. Atorvastatin decreased cholesterol concentrations independent of genotype. Whereas atorvastatin produced no significant changes in plasma nitrite, nitrate, or cGMP concentrations in both genotype groups, atorvastatin increased whole blood nitrite concentrations and decreased plasma TBA-RS concentrations in the CC (but not in the TT) genotype group. These findings suggest that the T-786C polymorphism modulates the effects of atorvastatin on NO bioavailability and oxidative stress.

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.

Endothelial nitric oxide synthase G894T (Glu298Asp) polymorphism was predictive of glycemic status in a 5-year prospective study of Chinese subjects with impaired glucose tolerance

Subjects with impaired glucose tolerance (IGT) have a high risk of developing type 2 diabetes mellitus (DM) and its related complications. However, both environmental and genetic factors may influence the progression or regression of hyperglycemia. Polymorphisms of the endothelial nitric oxide synthase (eNOS) gene have been associated with DM in cross-sectional studies, but their predictive values in glycemic progression are not known. We examined the relationship of the eNOS promoter -T786C (-T786C), intron 4 variable tandem repeat (in4a/b), and exon 7 G894T (G894T) polymorphisms, and their haplotypes, with the long-term glycemic outcome in a Chinese cohort with IGT. Two hundred fifty-six Chinese subjects with IGT at baseline participated in a 5-year follow-up study to assess their glycemic outcome. Each individual was genotyped for the above-mentioned polymorphisms. At 5 years, 40.2% of the subjects had reverted to normal glucose tolerance; 39.9% remained in IGT/impaired fasting glucose and 19.9% had developed DM. A significant gene effect of exon 7 G894T polymorphism on glycemic status at 5 years was demonstrated, with carriers of T(894) being more likely to have persistent hyperglycemia compared with GG subjects (P = .003). On stepwise logistic regression analysis, the presence of the T allele remained a significant risk factor for persistent hyperglycemia (odds ratio, 2.72; 95% confidence interval, 1.36-5.99; T+ vs GG; P = .013), together with male sex, high body mass index, and high 2-hour glucose at baseline. No significant effect of -T786C or in4a/b polymorphism on fifth-year glycemic status was observed. The eNOS G894T polymorphism appears to be predictive of persistent hyperglycemia in Chinese subjects with IGT.

Susceptible and protective eNOS haplotypes in hypertensive black and white subjects

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene have been inconsistently associated with hypertension. This inconsistency may derive from population stratification secondary to ethnic diversity, and consideration limited to only one rather than combinations of polymorphisms. We studied three genetic variations in the eNOS gene: a single nucleotide polymorphism in the promoter region (T-786C), in exon 7 (Glu298Asp), and a variable number of tandem repeats in intron 4 (b/a) of the eNOS gene in hypertensives (112 whites and 91 blacks) and normotensives (113 whites and 87 blacks). In addition, we also examined the association of eNOS gene haplotypes with hypertension in white and black subjects. No differences were observed in the frequencies of genotypes and alleles of the three polymorphisms when white hypertensives and white normotensives were compared, or when black hypertensives and black normotensives were compared (all P>0.05). Conversely, the haplotypes "T Asp b" and "C Glu b" were more common among white (16 and 24%, respectively) and black (17 and 16%, respectively) normotensives than in white (7 and 8%, respectively) and black (4 and 6%, respectively) hypertensives, respectively (all P<0.0039). In addition, the haplotype "C Asp b" was more commonly found in white hypertensives than in white normotensives (P=0.0007). These results suggest a contribution of eNOS haplotypes to the development of hypertension that is obscured when specific eNOS genotypes alone are considered. In addition, our results suggest two eNOS haplotypes associated with a protective effect against hypertension in both ethnic groups, and one eNOS haplotype conferring susceptibility to hypertension in white subjects.

A −786T>C polymorphism in the endothelial nitric oxide synthase gene reduces serum nitrite/nitrate levels from the heart due to an intracoronary injection of acetylcholine

We identified a -786T>C polymorphism in the eNOS gene, and this polymorphism was strongly associated with coronary spasm. The present study aimed to elucidate whether the -786T>C polymorphism or acetylcholine (ACh)-induced coronary spasm affects serum nitrite/nitrate (NOx) levels. The study population comprised three groups: (i) 26 patients without coronary spasm in the left anterior descending coronary artery (LAD) with the T/T genotype (group A); (ii) 20 patients with coronary spasm in the LAD with the T/T genotype (group B); and (iii) 16 patients with coronary spasm in the LAD with the C/T genotype (group C). Paired blood samples were obtained from the coronary sinus (CS) and the aortic tract (Ao) before and after an intracoronary injection of ACh. Serum NOx and plasma lactate levels were measured. The delta NOx level was calculated as the serum concentration of NOx in the CS minus that in the Ao. We compared lactate extraction ratios (LERs) and delta NOx levels between the three groups. The LERs after the provocation test in groups A, B and C were 18.9+/-2.4%, -0.5+/-3.9% and -13.5+/-4.2%, respectively. The LER in group C was significantly lower than in group B. The delta NOx levels after the provocation test in groups A, B and C were 11.5+/-1.7 micromol/l, 10.4+/-3.5 micromol/l and -2.1+/-4.8 micromol/l, respectively. The delta NOx levels in group C were significantly lower (P<0.05). Although the NOx level was significantly increased after the provocation test in group A (P<0.05), the NOx level was significantly decreased after the provocation test in group C (P=0.001). In group B, the provocation test did not significantly change the delta NOx level. In conclusion, the -786T>C polymorphism reduces the NOx level from the heart due to an intracoronary injection of ACh, and thereby predisposes the patients to severe coronary spasm.

Endothelial nitric oxide synthase gene haplotypes associated with circulating concentrations of nitric oxide products in healthy men

OBJECTIVES

Controversy exists regarding the effects of polymorphisms in the endothelial nitric oxide synthase (eNOS) gene on nitrites/nitrates (NOx) plasma concentrations. In this study we compared the distribution of haplotypes involving three relevant eNOS polymorphisms (T-786C in the promoter region; b/a in intron 4, and Glu298Asp in exon 7) in healthy subjects with low and high circulating NOx levels.

METHODS

We studied 154 healthy subjects (fasting, white males, who were non-smokers, 18-60 years of age, and not taking any medication). Genomic DNA was isolated from blood samples and genotypes were determined by PCR and restriction fragment length digestion. Circulating NOx was determined by chemiluminescence.

RESULTS

Haplotype frequencies were compared in two groups of subjects: those with the 30 lowest NOx levels (group L) and those with the 30 highest NOx levels (group H). NOx levels in group L and H were 24.2+/-4.5 microM and 80.9+/-8.9 microM, respectively. Genotype frequencies for the three polymorphisms were not different when the two groups were compared (all P>0.05, chi-squared test). However, the haplotype including the alleles C (promoter), 4b (intron 4), and Glu (exon 7) was significantly more common in group L (16%) than in group H (4%) (P=0.0047). The frequencies of the remaining haplotypes were not different among group L and H.

CONCLUSIONS

While eNOS genotypes are not significantly associated with changes in the circulating NOx concentrations, the specific eNOS haplotype that includes the 'C', '4b', and 'Glu' alleles is associated with lower circulating NOx concentrations.

Endothelial nitric oxide synthase haplotypes affect the susceptibility to hypertension in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) and hypertension (HT) commonly coexist. While endothelial nitric oxide synthase (eNOS) haplotypes have been associated with HT, it is unknown whether eNOS genotypes/haplotypes are associated with altered susceptibility to HT in patients with T2DM. We studied the distribution of three eNOS genetic polymorphisms: a single nucleotide polymorphism in the promoter region (T(-786)C), in exon 7 (Glu298Asp), and a variable number of tandem repeats in intron 4(b/a). Genotypes were determined for 102 healthy controls, 119 patients with HT, 66 patients with T2DM, and 113 patients with T2DM+HT. In addition, we also compared the distribution of eNOS haplotypes in the four groups of subjects. No differences were found in genotype and allele distribution among the four groups. Conversely, the haplotypes "C Glu b" and "C Asp b" were, respectively, more and less common in healthy controls than in HT or in T2DM+HT groups (24% versus 6% and 5%, respectively; both P<0.00625; and 8% versus 18% and 18%, respectively; both P<0.00625). Moreover, DM patients presented an overall distribution of eNOS haplotypes that was not different from healthy controls (P>0.05). Additionally, the haplotypes "C Glu b" and "C Asp b" were, respectively, more and less common in T2DM group than in T2DM+HT group (19% versus 5%; and 7% versus 18%, respectively; both P<0.00625). Our findings suggest a protective effect for eNOS haplotype "C Glu b" against the development of hypertension, and that haplotype "C Asp b" increases the susceptibility to hypertension in patients without or with T2DM.

Polymorphisms of chemokine receptors and eNOS in Brazilian patients with sickle cell disease

Sickle cell disease (SCD) is an inherited disorder that presents extremely variable clinical manifestations. For the past few decades, it has been approached as an inflammatory disorder, and several researchers have tried to determine the factors involved in such characteristic. In order to contribute to the identification of the genetic differences underlying this phenotypic diversity in SCD, we proposed to study the distribution of polymorphic variants of the genes encoding the chemokine receptors CCR2 and CCR5, as well as three polymorphisms in the NOS3 gene, in Brazilian SCD patients. These genes are involved in the development of inflammatory immune reactions, a feature believed to be of extreme importance in SCD pathology. Our results indicate that the polymorphisms studied here are not directly associated with severe clinical manifestations in SCD patients. Nevertheless, we observed a tendency for the development of a severe clinical course in carriers of the variant alleles CCR2-64I and CCR5delta32 and in homozygotes for the -786C variant of the NOS3 gene. Further studies should be carried out in order to assess the role of such variants in the clinical picture of SCD.

eNOS genotype-dependent correlation between whole blood lead and plasma nitric oxide products concentrations

Experimental data indicate that lead exposure decreases nitric oxide (NO) availability. However, no previous study has examined whether lead exposure affects plasma nitrite/nitrate (NO(x)) concentrations in humans. In addition, the T(-786)C polymorphism affects endothelial NO synthase (eNOS) expression and endogenous NO release. Here, we investigated whether there is an association between the circulating concentrations of NO(x) and the concentrations of lead in whole blood (B-Pb) and in plasma (P-Pb) from lead-exposed subjects. In addition, we also evaluated whether eNOS genotype for the T(-786)C polymorphism affects NO(x) concentrations in lead-exposed subjects. We studied 104 subjects exposed to lead who were non-smokers, 18-60 years of age, and not alcohol consumers. Genomic DNA was isolated from blood samples and genotypes for the T(-786)C polymorphism were determined by PCR and restriction fragment length digestion. Circulating NO(x) was determined by chemiluminescence. B-Pb and P-Pb were determined by inductively coupled plasma mass spectrometry and by graphite furnace atomic absorption spectrometry, respectively. No significant correlations were found between NO(x) and B-Pb and P-Pb measured in the 104 subjects (all P > 0.05). However, while no significant correlation was found in subjects with TT genotype, a negative correlation was found between plasma NO(x) and B-Pb (r = 0.230, P = 0.048) and P-Pb (r = 0.194, P = 0.110) in subjects from TC + CC genotypes group. Our study shows a negative correlation between plasma NO(x) concentrations and B-Pb in carriers of the "C" allele, thus suggesting a possible mechanism possibly involved in lead exposure-induced increase in the susceptibility to cardiovascular diseases.

Consistent interethnic differences in the distribution of clinically relevant endothelial nitric oxide synthase genetic polymorphisms

A maldistribution of endothelial nitric oxide synthase (eNOS) genetic variants may explain differences in NO-mediated effects and response to drugs among black and white subjects. While interethnic differences in the distribution of eNOS genetic variants exist in the American population, it is not known whether such interethnic differences exist in other populations. To test this possibility, we examined the distribution of genetic variants of three clinically relevant eNOS polymorphisms (T(-786)C in the promoter, the VNTR in intron 4, and the Glu298Asp variant in exon 7) in 136 black and 154 white subjects from a Brazilian population, which is very heterogeneous. We also estimated the haplotype frequency and evaluated associations between these variants. The Asp298 variant was more common in whites (32.8%) than in blacks (15.1%) (P < 0.004). Similarly, the C(-786) variant was more common in whites (41.9%) than in blacks (19.5%) (P < 0.0004). However, the 4a variant was more common in blacks (32.0%) than in whites (17.9%) (P < 0.003). The most common predicted haplotype in both ethnic groups combined only wild-type variants. While the second most common haplotype in blacks includes the variant 4a and the wild-type variants for the remaining polymorphisms, the second most common haplotype in whites includes the variants Asp298 and C(-786) and the wild-type variant for polymorphism in intron 4. The marked interethnic differences that we found in Brazilians are very similar to those previously reported in Americans. These findings strongly suggest a consistent difference in the distribution of eNOS genetic variants in blacks compared with whites and indicate that the interethnic differences do not vary with geographic origin.