Endothelial Nitric Oxide Gene Research Articles

Pathogenetic role of a number of factors in the development and progression of preeclampsia with varying severity in pregnant women.

Context Preeclampsia is a common pregnancy complication, posing significant risks to both the mother and fetus. Predicting and determining the risks of this disease is crucial. Aims This research aims to understand the pathogenetic role of several factors in the development and progression of preeclampsia, particularly in relation to its severity in pregnant patients. Methods The study included 60 pregnant women diagnosed with either mild or severe preeclampsia and 40 healthy pregnant women for comparison. Blood plasma was analysed using biochemical methods, and blood microcirculation parameters were determined to identify homeostatic abnormalities in early preeclampsia. Key results A molecular genetic study revealed the frequency of the endothelial nitric oxide gene eNOSC774T . Homeostatic abnormalities were statistically correlated with polymorphic genotypes of the eNOSC774T gene. Conclusions The research found a correlation between the T774T eNOS genotype mutation and the severity of preeclampsia, alongside significant homeostasis abnormalities in patients. Implications The T774T mutant genotype of the eNOS gene and higher levels of lipid peroxidation products are strongly linked to the severity and progression of preeclampsia. This highlights a significant connection between genetic predisposition and biochemical abnormalities in the disease's development.

Higher Levels of Shear Stress Downregulate Endothelin‐1 mRNA Expression

BackgroundPhysical inactivity has been shown to be a risk factor in the development of endothelial dysfunction. Endothelin‐1 (EDN‐1), a potent vasoconstrictor contributes to the pathogenesis of cardiovascular disease. Exercise‐induced endothelial shear stress (ESS) is a mechanical stimulus caused by alterations in blood flow patterns that regulates vascular function. Although it has been reported that higher levels of ESS may act as a protective mechanism to prevent vascular dysfunction, the role of pulsatile exercise‐induced ESS with varying exercise intensities has not been explored. Therefore, the purpose of this study was to determine the effects of pulsatile exercise‐induced ESS based on in vivo exercise intensity on EDN‐1 expression.MethodsCommercially available human umbilical vein endothelial cells (HUVEC; Sigma‐Aldrich, St Louis, MO) were cultured until 90–100% confluence. Exercise‐induced ESS in vivo was obtained from our previous reports. Cultured HUVEC cells were exposed to pulsatile resting ESS (18 dynes/cm2) for 2 hours, followed by 1 hour at resting ESS, low‐intensity exercise‐induced ESS (35 dynes/cm2), moderate exercise‐induced ESS, or high‐intensity exercise‐induced ESS (75 dynes/cm2) on a closed circuit pump and channeled slide (Ibidi pump system (PumpControl Software 1.5.4) and slides, Ibidi Inc., Fitchburg, WI). A set of cells were exposed to physiologically low shear stress levels (10 dynes/cm2) for 3 hours as a control. Total RNA was extracted and reverse transcribed followed by measurement of EDN‐1 mRNA expression via qRT‐PCR. qRT‐PCRs were performed in duplicates and changes in gene expression were calculated using the ΔΔ‐CT method with GAPDH used as the normalizing control gene. Statistical analysis was performed using graphpad prism 8 software (Graphpad Software.). Significance was considered at p<0.05.ResultsEDN‐1 mRNA expression was significantly downregulated following low and high intensity exercise‐induced ESS compared to resting conditions (p<0.05). Moderate intensity exercise induced ESS showed a trend downregulation in EDN‐1 mRNA expression compared to resting conditions (p<0.10).ConclusionsOur data suggests that higher levels of pulsatile exercise‐induced ESS are needed to suppress mRNA expression of EDN‐1. Although moderate intensity exercise induced ESS showed only a trend difference in mRNA expression compared to resting conditions, we have previously reported that moderate exercise‐induced ESS was shown to upregulate endothelial nitric oxide gene expression, a key vasodilatory enzyme that may prevent vascular dysfunction.

Endothelial Nitric Oxide Synthase Gene Polymorphisms Increase Risk of Deep Vein Thrombosis by Altering Homocysteine Levels.

Deep Vein Thrombosis (DVT) is a multicausal disease involving both acquired as well as genetic factors. Nitric oxide is an influential endogenous factor having its role in the development of deep vein thrombosis. It maintains the vascular integrity and any alterations in its levels may lead to a thrombotic event. It may also modulate homocysteine metabolism to cause hyperhomocysteinemia, which is a prominent risk factor for thrombosis. The objective of the study was to study if endothelial nitric oxide gene polymorphisms, 894G/T, and 2479G/A alter the plasma nitric oxide and homocysteine levels which may eventually increase the risk of deep vein thrombosis. One hundred Doppler ultrasonography and computerized tomography confirmed (for cerebral venous thrombosis), non-related DVT patients (M:F = 58:42; age range = 18 to 61 years) served as the study population. Two hundred hospital staff and their relatives or unrelated attendants of the patients served as the controls. Nitric oxide levels were determined by measuring its metabolites (NOx), and EIA was used to measure homocysteine levels. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for detecting the eNOS polymorphisms 894G/T and 2479G/A. In total, DVT subjects have 25% higher plasma levels of homocysteine and 37% lower levels of NOx in their circulation when compared to controls. In tertile analysis of nitric oxide and homocysteine levels, 894G/T and 2479G/A polymorphisms were associated with plasma nitric oxide and homocysteine levels. The increased risk of deep vein thrombosis was associated with endothelial nitric oxide gene polymorphisms and nitric oxide levels, but homocysteine levels were not a risk for deep vein thrombosis. The present study demonstrates that 894G/T and 2479G/A polymorphisms interact with lower levels of nitric oxide and higher levels of homocysteine that may possess the risk of deep vein thrombosis.

Role of polymorphisms of the endothelial nitric oxide synthase gene in predicting slow-flow phenomenon after primary percutaneous coronary intervention.

The aim of the present study was to examine the association between 2 polymorphisms of the endothelial nitric oxide (eNOS) gene (-786T>C and +894G>T) and the no-reflow/slow-flow phenomenon in post-primary percutaneous coronary intervention (PPCI) patients. A total of 103 post-PPCI patients were enrolled. Coronary no-reflow phenomenon was defined as a Thrombolysis in Myocardial Infarction (TIMI) flow grade 0-1 and coronary slow-flow phenomenon (CSFP) was defined as a TIMI flow grade ≤2. Due to the small number of post-PPCI patients with the no-reflow phenomenon (n=4), the primary comparison was made between CSFP (n=20) and normal flow (n=83) groups. There was a greater frequency of CSFP among carriers of the -786C allele of the eNOS -786T>C polymorphism (odds ratio [OR]: 3.90; 95% confidence interval [CI]: 0.87-17.45; p=0.07). However, no such association was detected between the +894T allele of the eNOS +894G>T and CSFP (OR: 0.92; 95% CI: 0.21-3.98; p=0.91). In the adjusted analysis, the -786T>C polymorphism did not reach statistical significance. There was no significant association between CSFP and 2 of the most common polymorphisms of the eNOS gene in post-PPCI patients.

Polymorphisme T-786C de l’eNOS dans la rétinopathie du diabète de type 1 chez la population algérienne

Diabetic retinopathy (DR) results from interactions between genetic and environmental factors. We were interested in the endothelial nitric oxide gene (eNOS), given the involvement of this enzyme in functional alterations in the retinal microvasculature in diabetes. The goal of our study was to assess the association of T-786C endothelial nitric oxide synthase (eNOS) gene polymorphism with diabetic retinopathy in the Algerian population. Our study enrolled 110 patients with and without DR. All subjects were genotyped for the T786C eNOS polymorphism using the PCR-RFLP method. We also investigated the association between this polymorphism and certain clinical and laboratory characteristics of patients with DR. A significant increase in the frequency of the CC genotype is noted in subjects without DR (P=0.03). We also report a significant increase in the frequencies of the TT+TC genotypes in individuals with DR (P=0.03). However, the association between the different genotypes and clinical or laboratory profiles in patients with DR reveals that the NO level is lower in subjects carrying the TT genotype (P=0.039). Our preliminary results suggest that the CC genotype could confer protection from type 1 diabetic retinopathy in the Algerian population, while the T allele seems to confer susceptibility.

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

Background/objectivesThe 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/methodsWe 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.ResultsThe 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).ConclusionsThese 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.

THE ROLE OF VARIABILITY OF CANDIDATE GENES eNOS, MnSOD2, ADRB1 IN THE DEVELOPMENT OF CARDIOVASCULAR PATHOLOGY IN NEWBORN

The study of gene polymorphism has been carried out to inform health care practitioners on genetic studies that can be used in clinical practice, and the genes under investigations aim at finding early manifestations of cardiovascular disorders. The possibility of determining the ways of correction of the detected cardiovascular pathology necessitates the prospect of further research starting from the neonatal period. To study the frequency of occurrence of genotypes of endothelial nitric oxide (eNOS) gene candidates polymorphism, mitochondrial superoxide dismutase (MnSOD2) 1 mutation and β1-adrenoreceptor (ADRB1) gene polymorphism in neonatal infants from perinatal risk groups the study involved examination of 186 newborns: 102 healthy full-term newborns, 25 newborns after asphyxia, 46 premature newborns and 13 newborns with intrauterine growth retardation. The study showed that the frequency of distribution of endothelial nitric oxide synthase (eNOS) C786T genotypes, mitochondrial superoxide dismutase (MnSOD2) T49C and β1-adrenergic receptor (ADRB1) Ser49Gly in newborns from perinatal risk groups in the neonatal period did not differ from healthy neonates.The CT genotype (p<0.05) of the endothelial nitric oxide synthase (eNOS) gene polymorphism C786T can be considered one of the predictors of cardiovascular development in newborns, which requires further clinical and instrumental comparison. Information on the prevalence of polymorphisms of genes associated with the development of cardiovascular events should be considered when developing a set of individual preventive measures.

PP.37.07] ASSOCIATION BETWEEN NITRIC OXIDE SYNTHASE POLYMORPHISMS AND ARTERIAL PROPERTIES IN GENERAL POPULATION

Objective: Nitric oxide plays an important role in vascular biology. Several single nucleotide polymorphisms (SNP) in the endothelial nitric oxide gene (NOS3) have been previously associated with arterial hypertension. We investigated whether these SNPs might be associated with arterial phenotypes in the Czech general population. Design and method: We genotyped three NOS3 SNPs in 426 subjects not treated for arterial hypertension (mean age, 49.1 years; 55.9% women). Arterial properties were measured using applanation tonometry. In multivariate-adjusted analyses, we assessed the gene effects of rs3918226 (665 C > T), rs1799983 (glu298asp G > T) and rs2070744 (786 T > C) on augmentation index (AIx), central augmentation pressure (AP) and aortic pulse wave velocity (PWV). Results: Carriers of rs3918226 mutated T allele (8% of the sample) had marginally higher AIx (145.3 ± 2.5 vs. 140.2 ± 1.1%; P = 0.064) and significantly higher AP (12.7 ± 0.7 vs. 11.1 ± 0.3 mmHg; P = 0.033). These associations were independent of potential confounding factors (sex, age, heart rate and smoking). Aortic PWV was not different in the two rs39182226 genotypes groups (P = 0.35). In single gene analyses, we did not observe any association between measured phenotypes and rs1799983 or rs2070744 (P > 0.11). In haplotype analysis, we observed trend for higher PWV in haplotypes containing rs3918226 mutated T allele compared with other allelic combination (P < 0.079). Conclusions: Mutated T allele of rs3918226 polymorphism in NOS3 gene was associated with parameters reflecting central arterial stiffness and wave reflection. We hypothesize that genetic modulation of intermediate arterial phenotypes might lead to higher blood pressure.

786T/c endothelial nitric oxide synthase gene polymorphism and coronary collateral circulation.

In this study, we investigated the association between -786T/C polymorphism of the endothelial nitric oxide (NOS3) gene in which thymidine is replaced by a cytosine at nucleotide -786 (rs 2070744) and coronary collateral circulation (CCC) in patients with stable coronary artery disease. 286 patients having a critical stenosis (> 95%) in at least one major epicardial coronary vessel were included in the study. CCC was defined according to the Rentrop classification (R). Patients with R0-1 CCC were included in the poor CCC group and subjects with R2-3 CCC were assigned to the good CCC group. The polymerase chain reaction method was used for genotyping. 152 patients with poor CCC and 134 patients with good CCC were examined. The frequency of cytosine-cytosine (CC) and thymidine-cytosine (TC) genotypes and allele C were higher in the poor CCC group, but the difference did not reach statistical significance. In the dominant model, the frequency of CC+TC vs. thymidine-thymidine (TT) genotypes was significantly higher in the poor CCC group (67.1% vs. 54.5%, respectively; χ²=4.78; p=0.02). In multivariate regression analysis, the dominant model for -786T/C polymorphism of the NOS3 gene remained as an independent correlate of poor CCC. -786T/C polymorphism of the NOS3 gene (rs 2070744) may be associated with poor angiogenesis and the development of CCC in stable coronary artery disease.

Endothelial nitric oxide gene polymorphisms and their association with coronary artery disease in Tunisian population

Objective:By releasing mediators, like nitric oxide (NO), vascular endothelium is considered so significant in the process of atherosclerotic. In fact, the major functions of NO consist in inhibiting the activation of platelet, relaxing the muscles (vascular and smooth ones), and modulating the growth and the migration of cells (vascular and smooth ones). Therefore, this process makes the endothelial nitric oxide synthase (NOS3) considerably important because it possesses atheroprotective activity. Polymophisms, rs1808593 (10G/T) as well as rs891512 (G24943A) within NOS3 gene, play major role in the coronary artery disease (CAD) development. The aim of the study is to evaluate the relationship between the 10G/T and G24943A polymorphisms and the CAD among Tunisian individuals.Methods:We included, in this survey, a set of 274 patients suffering from CAD together with 162 normotensive subjects. The PCR-RFLP was app- lied to analyze the polymorphism of intron 23 (10G/T) gene, while the ASA-PCR was used to analyze the intronic G24943A gene polymorphism. Overall and subgroup analyses were performed. Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the association bet- ween NOS3 10G/T and G24943A polymorphisms as well as CAD risk. Statistical analysis was performed with SPSS V.10.Results:The genotype frequencies for G24943A polymorphism differed significantly between the CAD patients and the controls. The former had a frequency of 11.4% for the AA genotype, 34.7% for the GA genotype and 53.9% for the GG genotype. The latter had a frequency of only 2.5% for the AA genotype, 29.7% for the GA genotype and 67.7% for the GG genotype (χ2=7.62; OR=1.79; p=0.006). The CAD patient group showed a significantly-higher frequency of the A allele compared to the controls (0.28 vs. 0.16; χ2=15.20; p<0.001). The odds ratio of CAD for A vs. G allele frequency was statistically significant 1.99 (1.4–2.82) at 95% CI. The genotype distribution for the 3 investigated variants of 10G/T were not significantly different between CAD and control subjects (χ2=1.46; OR=1.72; p=0.22). Whereas, 10G/T has revealed barely allelic (χ2=4.45; OR=2.3; p=0.034) correlation with coronary artery diseaseConclusion:The present study was designed so that there would be an association between the CAD and NOS3 polymorphism (G24943A). Howe- ver, these results have proven that the polymorphism of 10G/T is not associated with CAD in the Tunisian population.

Association between endothelial NO synthase polymorphisms and arterial properties in the general population

ObjectiveNitric oxide plays an important role in vascular biology. Several single nucleotide polymorphisms (SNP) in the endothelial nitric oxide gene (NOS3) have been previously associated with arterial hypertension. We investigated whether these SNPs might be associated with arterial phenotypes in the Czech general population. MethodsWe genotyped three NOS3 SNPs in 426 subjects not treated for arterial hypertension (mean age, 49.1 years; 55.9% women). Arterial properties were measured using applanation tonometry. In multivariate-adjusted analyses, we assessed the gene effects of rs3918226 (−665 C > T), rs1799983 (glu298asp G > T) and rs2070744 (786 T > C) on augmentation index (AIx), central augmentation pressure (AP) and aortic pulse wave velocity (PWV). ResultsCarriers of rs3918226 mutated T allele had marginally higher AIx (145.3 ± 2.5 vs. 140.2 ± 1.1%; P = 0.064) and significantly higher AP (12.7 ± 0.7 vs. 11.1 ± 0.3 mm Hg; P = 0.033). These associations were independent of potential confounding factors. Aortic PWV was not different in the two rs39182226 genotypes groups (P = 0.35). In single gene analyses, we did not observe any association between measured phenotypes and rs1799983 or rs2070744 (P ≥ 0.11). In haplotype analysis, we observed trend for higher PWV in haplotypes containing rs3918226 mutated T allele compared with other allelic combination (P ≤ 0.079). ConclusionMutated T allele of rs3918226 polymorphism in NOS3 gene was associated with parameters reflecting central arterial stiffness and wave reflection. We hypothesize that genetic modulation of intermediate arterial phenotypes might lead to higher blood pressure.

Endothelial nitric oxide (eNOS) gene G894T and VNTR polymorphisms are closely associated with the risk of ischemic stroke development for Asians: meta-analysis of epidemiological studies

Although the relationships between endothelial nitric oxide synthase (eNOS) gene polymorphisms (including G894T, VNTR and T786C) and risk of ischemic stroke (IS) have been extensively studied, controversial results have been reported. The aim of this study was to assess the relationships between them by using a meta-analysis. Literatures were retrieved through the following databases: Medline, Embase and Wangfang (updated to January 1st, 2013). Fixed- or random-effects model was used to calculate pooled odds ratio and 95 % confidence interval (OR and 95 % CI). A total of 31 case-control studies including 8,547 patients and 9,117 controls were included in this meta-analysis eventually. For eNOS G894T polymorphism, the results indicated that TT genotype was significantly associated with increased risk of IS incidence compared to G allele (OR and 95 % CI 1.25 (1.09-1.42) for TT vs. GT+GG, P < 0.001). When subgroup analysis was conducted according to ethnicities, T allele was significantly associated with risk of IS for Asians rather than for Caucasians. For eNOS VNTR polymorphism, 4aa genotype was significantly associated with risk of IS incidence compared to 4bb genotype (OR (95 % CI) 2.22 (1.66-2.97) for aa vs. bb, P < 0.001). Similarly, when subgroup analyses were conducted, 4aa was closely associated with increased risk of IS for Asians rather than for Caucasians. For eNOS T786C polymorphism, it was not associated with risk of IS incidence. In conclusion, this study indicated that eNOS 894T and VNTR 4a allele was significantly associated with risk of IS incidence for Asians. However, eNOS T786C polymorphism was not a likely risk factor for IS incidence.

Chronic intermittent hypoxia causes endothelial dysfunction in a mouse model of diet-induced obesity

BackgroundObstructive sleep apnea (OSA) is a common disorder characterized by chronic intermittent hypoxia (CIH). OSA is prevalent in obese subjects and is associated with endothelial dysfunction and cardiovascular disorders. We tested the hypothesis that the deleterious effects of IH could be further modulated by diet-induced obesity. DesignThirty adult (8–10weeks) male C57BL/6J mice were divided into four groups. Mice were subjected to CIH or intermittent air (IA) for 12h a day and fed either a high fat (HF) or a low fat control diet (CD) for 6weeks. We analyzed endothelial function using a wire myograph, and measured markers of oxidative stress (plasma malondialdehyde (MDA) and total antioxidant capacity (TAC)) using colorimetrical assays. We also measured C-reactive protein (CRP) using ELISA and endothelial nitric oxide (eNOS) gene expression using real time PCR. ResultsStimulated endothelial dependent dilation was significantly impaired only in the group fed high fat diet and subjected to CIH (Emax: HFIH 78±2%, p<0.0001) when compared to the other groups (Emax: HFIA 95±0.7%, CDIH 94±2%, CDIA 97±1%). Also basal endothelial dependant dilation was attenuated in the HFIH group compared to the HFIA group (Emax: HFIH: 179±10% vs. HFIA: 149±11% in the presence of L-NAME). Levels of MDA were elevated in the CDIH group when compared to CDIA (0.68±0.04 vs. 0.41±0.03μM, p<0.05) but were greatest in the HFIH group (0.83±0.08μM, p<0.05). However, there was no significant increase in MDA levels in the HFIA group (0.45±0.03μM, p=NS) when compared to all other groups. Similar effects were observed with CRP levels; CRP levels were significantly higher in the CDIH group compared with intermittent air (10.39±0.38 vs. 8.70±0.21μg/ml, p<0.05) but the HFIH had the greatest levels of CRP (11.87±0.31μg/ml, p<0.05). In the HFIA group, CRP levels were not elevated (9.96±0.37μg/ml, p=NS). Nevertheless, total antioxidant capacity and eNOS gene expression were not significantly different in the groups. ConclusionCIH caused endothelial dysfunction in mice fed an obesogenic diet. Inflammation and oxidative stress were increased in CIH and an obesogenic diet exacerbated these effects.

ENOS polymorphism associated with metabolic syndrome in children and adolescents

We investigated whether genetic polymorphisms in the endothelial nitric oxide (eNOS) gene (T(786)C in the promoter region, Glu298Asp in exon 7, and 4b/4a in intron 4) or eNOS haplotypes are associated with metabolic syndrome (MetS) in obese children and adolescents. We studied 242 subjects: 108 healthy (controls), 64 normotensive obese, and 70 obese children and adolescents with MetS. Genotypes were determined by Taqman(®) allele discrimination assay and real-time polymerase chain reaction (PCR), and PCR followed by fragment separation by electrophoresis. We compared the distribution of eNOS genotypes, alleles, and haplotypes in the three groups of subjects. The CC genotype for the T(786)C polymorphism was more common in the MetS group than in the control group (OR = 3.27; CI 1.81-9.07; P < 0.05). However, we found no significant differences in the distribution of eNOS haplotypes (P > 0.00625; P for significance after correction for multiple comparisons). Our findings suggest that while eNOS haplotypes are not relevant, the CC genotype for the T(786)C polymorphism is associated with MetS in obese children and adolescents. Further studies examining interactions of eNOS haplotypes with environmental factors and other genetic markers are warranted.

Endothelial nitric oxide gene haplotype reduces the effect of a single bout of exercise on the vascular reactivity in healthy subjects

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene reduce shear stress-induced nitric oxide production. Thus, we investigated the individual and combined impact of 3 variants in the eNOS gene (-786T>C, intron 4b4a, and 894G>T) on vascular reactivity before and after exercise. Sedentary, healthy subjects were studied (105 women/26 men, age 32 ± 1 years [mean ± standard error of the mean]). Genotypes were determined by polymerase chain reaction restriction fragment length polymorphism, and haplotypes were determined by a Bayesian-based algorithm. Vascular reactivity was evaluated by the percentage of change in forearm vascular conductance provoked by 5 minutes of circulatory occlusion before (baseline) and 10, 60, and 120 minutes after a maximal cardiopulmonary exercise test. Vascular reactivity increased 10 minutes after exercise in the entire sample (baseline: 218 ± 11% vs 10 minutes: 284 ± 15%, P < 0.001), remained increased at 60 minutes (239 ± 12%, P = 0.02 vs baseline), and returned to baseline at 120 minutes (210 ± 10%, P = 0.83 vs baseline). Genotype analysis showed that subjects with the 894G>T polymorphism had lower vascular reactivity than wild counterparts (group effect, P = 0.05). Furthermore, subjects with haplotype 2 (H2), containing the -786T>C and 894G>T polymorphisms, had lower vascular reactivity than wild counterparts (haplotype 1 [H1]) (group effect, P = 0.05), whereas subjects with haplotype 4 (H4), containing only the 894G>T polymorphism, had vascular reactivity similar to that of wild counterparts (H1) (group effect, P = 0.35). Altogether, these results indicate that the 894G>T polymorphism reduced exercise-mediated increase in vascular reactivity, particularly when it occurred concomitantly with the -786T>C polymorphism.

Association between endothelial nitric oxide gene intron 4a4b VNTR polymorphism and plasma homocysteine concentrations in Tunisian male patients with myocardial infarction

Many studies have shown that hyperhomocysteinemia may be an independent risk factor for coronary artery disease. However, not all prospective studies support an association between elevated plasma homocysteine levels and coronary artery disease. Nitric oxide (NO) plays a relevant role in various events during atherogenesis, and in vitro data suggest that NO may modulate total homocysteine (tHcy) concentrations, whereas polymorphisms of the endothelial nitric oxide (NOS3) gene have been reported to be related to an increased risk of myocardial infarction (MI) and hyperhomocysteinemia, but the results have been controversial. We hypothesized that the NOS3 synthase 4a4b VNTR polymorphism is a determinant of tHcy concentrations and tested this in 310 patients with MI and 250 controls. The NOS3 gene intron 4a4b VNTR polymorphism was analyzed by polymerase chain reaction analysis. There was no significant difference in the homocysteine levels between patients with MI and controls. The frequencies of the NOS34b4b, 4b4a, and 4a4a genotypes in the MI group were significantly different from those in the control group. In patients with MI, plasma tHcy concentrations were significantly different among the NOS3 genotypes (13.5±4.5, 18.5±3.9, and 20.4±2.1 μmol/L for 4b4b, 4a4b, and 4a4a genotypes, respectively; P<.001). However, no significant difference was observed for tHcy concentrations in the control group. In conclusion, the NOS34a4b gene polymorphism (presence of 4a allele) is associated with MI and influences plasma tHcy concentrations in patients with MI in the Tunisian male population.

Endothelial nitric oxide synthase (eNOS) genetic polymorphisms among Egyptian systemic lupus erythematosus and rheumatoid arthritis patients

Several genetic polymorphisms in the endothelial nitric oxide (eNOS) gene have been associated with different vascular, infectious, and autoimmune disease in some populations. These polymorphisms may alter the levels of eNOS expression, thus being relevant either to the pathogenesis or progression of these diseases. We aimed to assess the prevalence of eNOS genetic polymorphisms namely, the 27-bp repeat in intron 4 by polymerase chain reaction (PCR) and T-786C mutation by PCR-RFLP, among Egyptian systemic lupus erythematosus patients (SLE) and rheumatoid arthritis (RA) patients. The study included 34 SLE and 34 RA patients. Forty-six age, sex, and ethnically matched healthy volunteers were included in the current study as a control group. The frequencies of intron 4 and T-786C polymorphisms in the SLE patient group were 73.5 % for the wild type versus 26.5 % for the polymorphic types and 38.2 % for the wild type versus 50 % for the heteromutant type and 11.8 % for the homomutant type, respectively. As for the RA group the frequencies of intron 4 and T-786C polymorphisms in the patient group were 76.5 % for the wild type versus 23.5 % for the polymorphic types and 44.1 % for the wild type versus 55.9 % for the polymorphic type, respectively, with no statistically significant difference in the distribution of the genotypes between SLE and RA patients and the control group. No association was detected between these genetic polymorphisms and the clinical features of the patients apart from an association between the T-786C genetic polymorphism and the extra-articular manifestations of RA.

Endothelial Nitric Oxide Synthase Polymorphisms and Adaptation of Parasympathetic Modulation to Exercise Training

There is a large interindividual variation in the parasympathetic adaptation induced by aerobic exercise training, which may be partially attributed to genetic polymorphisms. Therefore, we investigated the association among three polymorphisms in the endothelial nitric oxide gene (-786T>C, 4b4a, and 894G>T), analyzed individually and as haplotypes, and the parasympathetic adaptation induced by exercise training. Eighty healthy males, age 20-35 yr, were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis, and haplotypes were inferred using the software PHASE 2.1. Autonomic modulation (i.e., HR variability and spontaneous baroreflex sensitivity) and peak oxygen consumption (VO(2peak)) were measured before and after training (running, moderate to severe intensity, three times per week, 60 min·day(-1), during 18 wk). Training increased VO(2peak) (P < 0.05) and decreased mean arterial pressure (P < 0.05) in the whole sample. Subjects with the -786C polymorphic allele had a significant reduction in baroreflex sensitivity after training (change: wild type (-786TT) = 2% ± 89% vs polymorphic (-786TC/CC) = -28% ± 60%, median ± quartile range, P = 0.03), and parasympathetic modulation was marginally reduced in subjects with the 894T polymorphic allele (change: wild type (894GG) = 8% ± 67% vs polymorphic (894GT/TT) = -18% ± 59%, median ± quartile range, P = 0.06). Furthermore, parasympathetic modulation percent change was different between the haplotypes containing wild-type alleles (-786T/4b/894G) and polymorphic alleles at positions -786 and 894 (-786C/4b/894T) (-6% ± 56% vs -41% ± 50%, median ± quartile range, P = 0.04). The polymorphic allele at position -786 and the haplotype containing polymorphic alleles at positions -786 and 894 in the endothelial nitric oxide gene were associated with decreased parasympathetic modulation after exercise training.

Variants of the Endothelial Nitric Oxide Gene and Cerebral Blood Flow after Severe Traumatic Brain Injury

Experimental studies suggest that nitric oxide produced by endothelial nitric oxide synthase (NOS3) plays a role in maintaining cerebral blood flow (CBF) after traumatic brain injury (TBI). The purpose of this study was to determine if common variants of the NOS3 gene contribute to hypoperfusion after severe TBI. Fifty-one patients with severe TBI were studied. Cerebral hemodynamics, including global CBF by the stable xenon computed tomography (CT) technique, internal carotid artery flow volume (ICA-FVol), and flow velocity in intracranial vessels, were measured within 12 h of injury, and at 48 h after injury. A blood sample was collected for DNA analysis, and genotyping of the following variants of the NOS3 gene was performed: -786T>C, 894G>T, and 27bp VNTR. Cerebral hemodynamics were most closely related to the-786T>C genotype. CBF averaged 57.7±3.0 mL/100 g/min with the normal T/T genotype, 47.0±2.5 mL/100 g/min with the T/C, and 37.3±8.8 mL/100 g/min with the C/C genotype (p=0.0146). Cerebrovascular resistance followed an inverse pattern with the highest values occurring with the C/C genotype (p=0.0027). The lowest ICA-FVol of 124±43 mL/min was found at 12 h post-injury in the more injured hemisphere of the patients with the C/C genotype (p=0.0085). The mortality rate was 20% in patients with the T/T genotype and 17% with the T/C genotype. In contrast, both of the patients with the C/C genotype were dead at 6 months post-injury (p=0.022). The findings in this study support the importance of NO produced by NOS3 activity in maintaining CBF after TBI, since lower CBF values were found in patients having the -786C allele. The study suggests that a patient's individual genetic makeup may contribute to the brain's response to injury and determine the patient's chances of surviving the injury. The results here will need to be studied in a larger number of patients, but could explain some of the variability in outcome that occurs following severe TBI.

Polymorphisms in the endothelial nitric oxide gene are associated with lower vascular reactivity after a maximal dynamic exercise

Our aim was to investigate the influence of three polymorphisms in the endothelial nitric oxide (eNOS) gene (−786T>C, intron 4b4a and 894G>T), on the vascular reactivity (VR) to an ischemic stimulus. We evaluated 106 healthy, sedentary, non-obese women (31 ± 9 years). Genotypes were determined by PCR-RFLP and haplotypes inferred based on the Bayesian method. VR was considered the change in forearm vascular conductance [blood flow (plethysmography) divided by mean blood pressure (auscultation); ml/100ml.min.100mmHg] provoked by 5 min of ischemia before, 10 and 60 min after a maximal cardiopulmonary exercise test (CPET). VR increased 10 min after the CPET in the entire sample (p<0.001 vs. baseline). Subjects with polymorphic alleles at position −786 and intron 4 had a trend for lower VR 10 min after the CPET versus wild type counterparts (−786CC: 7.7 ± 1.5 vs. −786TT: 10.1 ± 0.6, p = 0.06; 4b4a/4a4a: 8.5 ± 5.9 vs. 4b4b: 10.0 ± 0.5, p = 0.06). In addition, a haplotype with polymorphic alleles at positions −786 and 894 (−786C/4b/894T; 8.9 ± 0.7) and another with polymorphic allele in intron 4 (−786T/4a/894G; 7.5 ± 1.3) had lower VR 10 min after the CPET versus a haplotype with wild type alleles (−786T/4b/894G; 10.1 ± 0.4, p = 0.02 and 0.05, respectively). Thus, these results suggest that the −786T>C, intron 4b4a and 894G>T polymorphisms are associated with lower VR after a maximal dynamic exercise. Support: CAPES, CNPq and FAPERJ.