The Glu298Asp polymorphism in the endothelial nitric oxide synthase gene is strongly associated with coronary spasm

Low HDL cholesterol and the eNOS Glu298Asp polymorphism are associated with inducible myocardial ischemia in patients with suspected stable coronary artery disease

BACKGROUND

The endothelial nitric oxide synthase (eNOS) gene deficiency is known to cause impaired coronary vasodilating capability in animal models. In the general clinical population, the eNOS gene polymorphisms, able to affect eNOS activity, were associated with cardiometabolic risk features and prevalence of coronary artery disease (CAD).

AIM

To investigate the association of eNOS Glu298Asp gene polymorphism, cardiometabolic profile, obstructive CAD and inducible myocardial ischemia in patients with suspected stable CAD.

METHODS

A total of 506 patients (314 males; mean age 62 ± 9 years) referred for suspected CAD was enrolled. Among these, 325 patients underwent stress ECG or cardiac imaging to assess the presence of inducible myocardial ischemia and 436 patients underwent non-invasive computerized tomography or invasive coronary angiography to assess the presence of obstructive CAD. Clinical characteristics and blood samples were collected for each patient.

RESULTS

In the whole population, 49.6% of patients were homozygous for the Glu298 genotype (Glu/Glu), 40.9% heterozygotes (Glu/Asp) and 9.5% homozygous for the 298Asp genotype (Asp/Asp). Obstructive CAD was documented in 178/436 (40.8%) patients undergoing coronary angiography while myocardial ischemia in 160/325 (49.2%) patients undergoing stress testing. Patients with eNOS Asp genotype (Glu/Asp + Asp/Asp) had no significant differences in clinical risk factors and in circulating markers. Independent predictors of obstructive CAD were age, gender, obesity, and low HDL-C. Independent predictors of myocardial ischemia were gender, obesity, low HDL-C and Asp genotype. In the subpopulation in which both stress tests and coronary angiography were performed, the Asp genotype remained associated with increased myocardial ischemia risk after adjustment for obstructive CAD.

CONCLUSION

In this population, low-HDL cholesterol was the only cardiometabolic risk determinant of obstructive CAD. The eNOS Glu298Asp gene polymorphism was significantly associated with inducible myocardial ischemia independently of other risk factors and presence of obstructive CAD.

Association of endothelial nitric oxide synthase (Glu298Asp) gene polymorphism with radial artery spasm during cardiac catheterization in Egyptians

BACKGROUND

Nitric oxide (NO) exerts diverse effects on the cardiovascular system. Impairment of NO production plays a key role in cerebral and coronary artery spasm. We aimed to explore the predicting factors of radial artery spasm (RAS) and the association of eNOS gene polymorphism (Glu298Asp) with RAS during cardiac catheterization.

METHODS AND RESULTS

200 patients underwent elective coronary angiography through a trans-radial approach. The subjects were genotyped to the Glu298Asp polymorphism (rs1799983) on the eNOS gene by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our results showed that the subjects with the TT genotype and T allele were significantly more likely to develop radial artery spasms (OR = 12.5, 4.6, P < 0.001 respectively). TT genotype of eNOS Glu298Asp polymorphism, number of punctures, size of the radial sheath, radial tortuosity, and right radial access are independent predictors of radial spasm.

CONCLUSION

The eNOS (Glu298Asp) gene polymorphism is associated with RAS during cardiac catheterization in Egyptians. TT genotype of eNOS Glu298Asp polymorphism, number of punctures, size of the radial sheath, right radial access, and tortuosity are independent predictors of RAS during cardiac catheterization.

Association of eNOS (G894T, rs1799983) and KCNJ11 (E23K, rs5219) gene polymorphism with coronary artery disease in North Indian population

Background

Endothelial nitric oxide synthase (eNOS) and potassium voltage-gated channel subfamily J member 11 (KCNJ11) could be the candidate genes for coronary artery disease (CAD). This study investigated the relationship of the eNOS (rs1799983) and KCNJ11 (rs5219) polymorphisms with the presence and severity of CAD in the North Indian population.

Methods

This study included 300 subjects, 150 CAD cases and 150 healthy controls. Single nucleotide polymorphism was evaluated by Polymerase chain reaction and Restriction fragment length polymorphism (PCR-RFLP). Analysis was performed by SPSS (version 21.0).

Results

We observed that KK genotype of KCNJ11E23K (rs5219) polymorphism (P=0.0001) genotypes and K allele (P=0.0001) was found to be a positive risk factor and strongly associated with CAD. In the case of eNOSG894T (rs1799983) there was no association found with CAD.

Conclusion

These results illustrate the probability of associations between SNPs and CAD although specific genetic polymorphisms affecting ion channel function and expression have still to be clarified by further investigations involving larger cohorts.

Coronary Artery Spasm: The Interplay Between Endothelial Dysfunction and Vascular Smooth Muscle Cell Hyperreactivity

Patients with angina pectoris, the cardinal symptom of myocardial ischaemia, yet without significant flow-limiting epicardial artery stenosis represent a diagnostic and therapeutic challenge. Coronary artery spasm (CAS) is an established cause for anginal chest pain in patients with angiographically unobstructed coronary arteries. CAS may occur at the epicardial level and/or in the microvasculature. Although the underlying pathophysiological mechanisms of CAS are still largely unclear, endothelial dysfunction and vascular smooth muscle cell (VSMC) hyperreactivity seem to be involved as major players, although their contribution to induce CAS is still seen as controversial. This article will look at the role and possible mechanistic interplay between an impaired endothelial and VSMC function in the pathogenesis of CAS.

Epicardial Coronary Spasm in Women With Angina Pectoris and Unobstructed Coronary Arteries Is Linked With a Positive Family History: An Observational Study

PURPOSE

Coronary spasm is frequently found in patients with angina and unobstructed coronaries. The pathophysiology is incompletely understood, although sex differences have been described. Often a positive family history (PFH) is encountered. We assessed the relationship between sex, coronary spasm, and a PFH for cardiovascular disease.

METHODS

This single-center observational study recruited 415 stable angina patients with unobstructed coronaries (no stenosis >50%) between 2008 and 2011 (mean [SD] age, 62 [10] years; 38% men). Patients were referred for angiography because of signs and symptoms of myocardial ischemia. Intracoronary acetylcholine (ACh) testing was performed in all patients according to a standardized protocol. Risk factor assessment included hypertension, hypercholesterolemia, diabetes, smoking, and a PFH. The latter was defined as a first-degree relative with myocardial infarction or stroke. Statistical analysis involved comparison of categorical and continuous variables. Multivariable analysis aimed at identifying predictors for a pathologic ACh testing, microvascular spasm, and a PFH.

FINDINGS

Epicardial spasm was found in 33% of patients and microvascular spasm in 30% of patients. A pathologic ACh test was more frequent in women than in men (72% vs 49%; P < 0.0005). A PFH was found in 55% of patients with significantly more women than men (61% vs 45%; P = 0.001). Among patients with epicardial spasm, women had a PFH significantly more often than men (66% vs 43%; P = 0.006). The latter difference was not found when comparing women and men with microvascular spasm.

IMPLICATIONS

There is a female preponderance among patients with angina and unobstructed coronaries. ACh testing enables detection of coronary spasm. Epicardial spasm in women is associated with a PFH.

Stress cardiomyopathy: Is it limited to Takotsubo syndrome? Problems of definition

In 2006, Takotsubo syndrome (TTC) was described as a distinct type of stress-induced cardiomyopathy (stress cardiomyopathy). However, when thinking about Takotsubo cardiomyopathy from the viewpoints of the AHA and ESC classifications, 2 possible problems may arise. The first potential problem is that a forecast of disease outcome is lacking in the ESC classification, whereas the AHA only states that 'outcome is favorable with appropriate medical therapy'. However, based on the literature data, one can make a general conclusion that occurrence of myocardial lesions in TTC (i.e., myocardial fibrosis and contraction-band necrosis) causes the same effects as in other diseases with similar levels of myocardial damage and should not be considered to have a lesser impact on mortality. To summarise, TTC can cause not only severe complications such as pulmonary oedema, cardiogenic shock, and dangerous ventricular arrhythmias, but also damage to the myocardium, which can result in the development of potentially fatal conditions even after the disappearance of LV apical ballooning. The second potential problem arises from the definition of TTC as a stress cardiomyopathy in the AHA classification. In fact, the main factors leading to TTC are stress and microvascular anginas, since, as has been already discussed, coronary spasm can cause myocardium stunning, resulting in persistent apical ballooning. Thus, based on this review, 3 distinct types of stress cardiomyopathies exist (variant angina, microvascular angina, and TTC), with poor prognosis. Adding these diseases to the classification of cardiomyopathies will facilitate diagnosis and preventive prolonged treatment, which should include intensive anti-stress therapy.

Association of depression with coronary artery disease and QTc interval prolongation in women with chest pain: data from the KoRean wOmen'S chest pain rEgistry (KoROSE) study

The presence of depression is reportedly related with cardiovascular diseases, including coronary artery disease (CAD), but little is known concerning the association between depressive symptoms reflecting the cultural constructions of female patients with chest pain as well as coronary artery stenosis, coronary vasospasm, and the corrected QT (QTc) interval. In a multicenter prospective cross-sectional survey of 163 Korean women with chest pain, the presence of depression was evaluated using the Beck Depression Inventory (BDI) and Lee and Rhee Depression (LRD) scales. The differences in the QTc interval and the presence of CAD (defined as ≥ 50% coronary artery stenosis on coronary angiography) and coronary vasospasm were compared between depressed and non-depressed women. Significant CAD was present in 83 of 163 female patients (mean age, 61 years), and coronary vasospasm was present in 11 of 80 patients. The mean BDI and LRD scores were significantly higher in patients with significant CAD (BDI: 13.4 ± 9.6 vs. 6.9 ± 5.6, p < 0.001; LRD: 46.9 ± 21.4 vs. 39.8 ± 15.2, p = 0.027) and coronary vasospasm (BDI: 12.3 ± 6.4 vs. 4.6 ± 2.8; and LRD: 49.8 ± 12.3 vs. 30.5 ± 13.9; both p < 0.05). On multivariate analysis, BDI scores were important risk factors for the presence of CAD (odds ratio [OR] = 1.138; 95% confidence interval [CI] = 1.071-1.210; p=0.021) and coronary vasospasm (OR = 2.534; 95% CI = 1.161-2.028; p = 0.003), with similar findings obtained for LRD scores (CAD: OR = 1.034; 95% CI = 1.013-1.056; p = 0.001; coronary vasospasm: OR = 1.125; 95% CI = 1.050-1.206; p = 0.001). The mean QTc interval was also significantly higher in the depressed group than in the non-depressed group (440.1 ± 32.0 ms vs. 408.2 ± 26.4ms; p < 0.001). The QTc interval displayed significant positive with the BDI (r = 0.595; p < 0.001) and LRD scores (r = 0.467; p< 0.001). This study demonstrated that depression is associated with a prolonged QTc interval, CAD, and coronary vasospasm in female patients with chest pain, suggesting a possible mechanism by which depressive mood may be linked with coronary endothelial dysfunction and atherosclerosis.

Association between the endothelial nitric oxide synthase gene Glu298Asp polymorphism and coronary heart disease: a meta‑analysis of 39 case‑control studies

Numerous studies have indicated that the human endothelial nitric oxide synthase (eNOS) gene Glu298Asp polymorphism is associated with coronary heart disease (CHD) susceptibility, however, their conclusions are inconsistent. The present meta‑analysis aimed to evaluate the precise result by searching the PubMed database and using 39 case‑control studies comprising 7489 cases and 7051 controls.Each study tested the association between the eNOS Glu298Asp polymorphism and CHD. A meta‑analysis was then conducted using the Comprehensive Meta Analysis 2.2 software to calculate the pooled odds ratios (ORs) of five genetic models with 95% confidence intervals (CIs). Publication bias was also explored. The meta‑analysis showed a significant association between the eNOS Glu298Asp polymorphism and CHD susceptibility for all the genetic models [Asp vs. Glu, OR 1.26, 95% CI 1.14‑1.40, P<0.001; Asp/Asp vs. Glu/Glu, OR 1.58, 95% CI 1.23‑2.02, P<0.001; Glu/Asp vs. Glu/Glu, OR 1.12, 95% CI 1.03‑1.22, P=0.001; (Glu/Asp+Asp/Asp) vs. Glu/Glu, OR 1.17, 95% CI 1.07‑1.27, P<0.001; Asp/Asp vs. (Glu/Glu+Glu/Asp), OR 1.59, 95% CI 1.25‑2.03, P<0.001]. Subgroup and sensitivity analyses indicated that the result was robust. A weak publication bias was detected. The results indicated that the eNOS Glu298Asp polymorphism is a risk factor for developing CHD, particularly in the Asian population.

Endothelial nitric oxide synthase (G894T) gene polymorphism in a random sample of the Egyptian population: comparison with myocardial infarction patients

AIM

The aim of this study was to detect endothelial nitric oxide synthase (eNOS) Glu298Asp gene variants in a random sample of the Egyptian population, compare it with those from other populations, and attempt to correlate these variants with serum levels of nitric oxide (NO). The association of eNOS genotypes or serum NO levels with the incidence of acute myocardial infarction (AMI) was also examined.

METHODS

One hundred one unrelated healthy subjects and 104 unrelated AMI patients were recruited randomly from the 57357 Hospital and intensive care units of El Demerdash Hospital and National Heart Institute, Cairo, Egypt. eNOS genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum NO was determined spectrophotometrically.

RESULTS

The genotype distribution of eNOS Glu298Asp polymorphism determined for our sample was 58.42% GG (wild type), 33.66% GT, and 7.92% TT genotypes while allele frequencies were 75.25% and 24.75% for G and T alleles, respectively. No significant association between serum NO and specific eNOS genotype could be detected. No significant correlation between eNOS genotype distribution or allele frequencies and the incidence of AMI was observed.

CONCLUSION

The present study demonstrated the predominance of the homozygous genotype GG over the heterozygous GT and homozygous TT in random samples of Egyptian population. It also showed the lack of association between eNOS genotypes and mean serum levels of NO, as well as the incidence of AMI.

On the epigenetics of vascular regulation and disease

Consolidated knowledge is accumulating as to the role of epigenetic regulatory mechanisms in the physiology of vascular development and vascular tone as well as in the pathogenesis of cardiovascular disease. The modulation of gene expression through modification of the epigenome by structural changes of the chromatin architecture without alterations of the associated genomic DNA sequence is part of the cellular response to environmental changes. Such environmental conditions, which are finally being translated into adaptations of the cardiovascular system, also comprise pathological conditions such as atherosclerosis or myocardial infarction. This review summarizes recent findings on the epigenetics of vascular regulation and disease and presents nutritional and pharmacological approaches as novel epigenetic strategies in the prevention and treatment of cardiovascular disease.

Pharmacogenetic association of NOS3 variants with cardiovascular disease in patients with hypertension: the GenHAT study

Nitric oxide synthase 3 (NOS3) catalyzes production of NO in the endothelium and may play a role in cardiovascular disease (CVD). We assessed the pharmacogenetic associations of three NOS3 polymorphisms and three antihypertensive drugs with CVD outcomes. Hypertensive subjects (n = 30,280) from a multi-center, double-blind clinical trial were randomized to chlorthalidone, amlodipine, or lisinopril treatment (mean follow up, 4.9 years). Outcomes included coronary heart disease (CHD: fatal CHD and nonfatal myocardial infarction); stroke; heart failure (fatal, requiring hospitalization, or outpatient treatment); all-cause mortality; and end-stage renal disease (ESRD). Main effects of NOS3 variants on outcome and genotype-treatment interactions were tested. For NOS3 −690 C>T (rs3918226), a higher hazard ratio (HR) was found in minor allele carriers for CHD (CC = 1.00, CT+TT = 1.12 (95% confidence interval (CI) = 1.00–1.26), P = 0.048). For NOS3 −922 A>G (rs1800779), a higher HR was found in minor allele carriers for heart failure (AA = 1.00, AG+GG = 1.10 (CI = 1.00–1.21), P = 0.046). Significant pharmacogenetic findings were observed for stroke and all-cause mortality. For −690 C>T, a lower HR was observed for stroke in minor allele carriers when treated with amlodipine versus lisinopril (CC = 0.85 (CI = 0.73–0.99), CT+TT = 0.49 (CI = 0.31–0.80), P = 0.04). For glu298asp G>T (rs1799983), a lower HR was observed for all-cause mortality in minor allele carriers when treated with amlodipine versus lisinopril (GG = 1.01 (CI = 0.91–1.13), GT+TT = 0.85 (CI = 0.75–0.97), P = 0.04). We observed significant associations with NOS3 variants and CHD and heart failure and significant pharmacogenetic effects for stroke and all cause mortality. This suggests that NOS3 variants may potentially provide useful clinical information with respect to treatment decisions in the future.

High prevalence of a pathological response to acetylcholine testing in patients with stable angina pectoris and unobstructed coronary arteries. The ACOVA Study (Abnormal COronary VAsomotion in patients with stable angina and unobstructed coronary arteries)

OBJECTIVES

This study aimed at determining the prevalence of epicardial and microvascular coronary spasm in patients with anginal symptoms, despite angiographically normal coronary arteries.

BACKGROUND

Despite a typical clinical presentation with exercise-related anginal symptoms (chest pain or dyspnea) with or without occasional attacks of resting chest pain suggestive of coronary artery disease, 40% of patients undergoing diagnostic angiography have normal or "near" normal coronary arteriograms. Many of these patients are given a diagnosis of noncardiac chest pain, and some are considered to have microvascular angina. However, we speculate that abnormal coronary vasomotion (reduced vasodilatation with exercise = reduced coronary flow reserve and/or vasospasm at rest) might also represent a plausible explanation for the symptoms of the patient.

METHODS

This was a prospective study in 304 consecutive patients (50% men, mean age 66 ± 10 years) with exertional anginal symptoms undergoing diagnostic angiography. A total of 139 patients (46%) had ≥50% coronary artery disease in at least 1 coronary artery, 21 patients (7%) had luminal narrowings ranging from >20% to 49%, and 144 patients (47%) had normal coronary arteries or only minimal irregularities (<20% diameter reduction).

RESULTS

One hundred twenty-four patients of the latter (86%) underwent intracoronary acetylcholine (ACH) testing, which elicited coronary spasm in 77 patients (62%), 35 patients (45%) with epicardial spasm (≥75% diameter reduction with reproduction of the symptoms of the patient) and 42 patients (55%) with microvascular spasm (reproduction of symptoms, ischemic electrocardiographic changes, and no epicardial spasm).

CONCLUSIONS

Nearly 50% of patients undergoing diagnostic angiography for assessment of stable angina had angiographically normal or near normal coronary arteriograms. The ACH test triggered epicardial or microvascular coronary spasm in nearly two-thirds of these patients. Our results suggest that abnormal coronary vasomotion plays a pathogenic role in this setting and that the ACH test might be useful to identify patients with cardiac symptoms, despite normal coronaries. (Abnormal Coronary Vasomotion in Patients With Suspected CAD But Normal Coronary Arteries; NCT00921856).

Deoxyribonucleic Acid copy number aberrations in vasospastic angina patients using an array comparative genomic hybridization

BACKGROUND AND OBJECTIVES

Vasospastic angina (VA) is a specific type of coronary artery disease and develops as a result of coronary artery spasm. Recently, a few studies have revealed that VA caused by coronary artery spasm is related to genetic traits. The objective of this study was to use the recently developed technique of array comparative genomic hybridization (CGH) to screen the genetic aberrations of VA.

SUBJECTS AND METHODS

To identify candidate genes that might be causally involved in the pathogenesis of VA, genomic deoxyribonucleic acids were extracted from whole blood of 28 patients with VA who presented at Department of Cardiology at Seoul St. Mary's Hospital, Seoul, Korea. The copy number profiles of these patients was then analyzed using array CGH and reverse transcriptase (RT) quantitative polymerase chain reaction (PCR).

RESULTS

Array CGH revealed gains in 31 different regions, with losses in the 4q35.2, 7q22.1, 10q26.3, 15q11.2, 16p13.11, 17p11.2 and 19q13.3 regions (more than 32% aberration in these regions). Several loci were found to be frequently including gains of 5p and 11q (50% of samples). The most common losses were found in 7q (54% of samples). Copy number aberrations in chromosomal regions were detected and corresponding genes were confirmed by RT quantitative PCR. The fold change levels were highest in the CTDP1 (18q23), HDAC10 (22q13.33), KCNQ1 (11p15.5-p15.4), NINJ2 (12p13.33), NOTCH2 (1p12-p11.2), PCSK6 (15q26.3), SDHA (5p15.33), and MUC17 (7q22.1) genes.

CONCLUSION

Many candidate chromosomal regions that might be related to the pathogenesis of VA were detected by array CGH and should be systematically investigated to establish the causative and specific genes for VA.

Endothelial nitric oxide synthase and angiotensinogen gene polymorphism in coronary artery diseases in Egypt

Genetic factors contribute to the pathogenesis of coronary artery disease (CAD). We studied 100 patients with CAD and 50 healthy individuals to assess the association of endothelial nitric oxide (eNOS) polymorphism (Glu298Asp) and angiotensinogen polymorphisms (M235T) and CAD in an Egyptian population. Serum nitric oxide (NO) and angiotensin I levels were also measured. The frequency of Glu298Asp and M235T polymorphisms were higher in the CAD group compared with controls. The mean level of NO was significantly lower (P < .05) while angiotensin I was significantly higher (P < .05) in patients CAD than in controls. The frequency of eNOS TT allele of M235T variant was significantly higher in patients with CAD (20% vs 6%). The frequency of angiotensinogen (AGT) TT and T allele in patients with CAD was significantly higher (P < .05) than in controls (22% vs 6%and 47% vs23%, respectively). Homozygosity for Glu298Asp and M235T polymorphisms may predispose to CAD.

eNOS G894T polymorphism and abdominal aortic aneurysms

BACKGROUND

The genetic risk factors that contribute to the risk of developing abdominal aortic aneurysm (AAA) are poorly understood. We assessed the association of endothelial nitric oxide synthase (eNOS) gene polymorphism with AAA.

METHODS

eNOS gene polymorphism of 61 patients with AAA and 62 control participants were analyzed by polymerase chain reaction (PCR)-restriction technique.

RESULTS

eNOS G894 homozygote T/T genotype polymorphism and 894T allele frequency in patients with AAA were significantly higher than those of the control participants (P = .01, P = .03). Among patients with AAA, the eNOS G894 T/T polymorphism and 894T allele frequency were associated with larger AAAs.

CONCLUSION

The current study, in a small group of participants, showed a relationship between eNOS G894T polymorphism and AAA.

Association of the 894G>T polymorphism in the endothelial nitric oxide synthase gene with risk of acute myocardial infarction

BACKGROUND

This study was designed to investigate the association of the 894G>T polymorphism in the eNOS gene with risk of acute myocardial infarction (AMI), extent of coronary artery disease (CAD) on coronary angiography, and in-hospital mortality after AMI.

METHODS

We studied 1602 consecutive patients who were enrolled in the GEMIG study. The control group was comprised by 727 individuals, who were randomly selected from the general adult population.

RESULTS

The prevalence of the Asp298 variant of eNOS was not found to be significantly and independently associated with risk of AMI (RR = 1.08, 95%CI = 0.77-1.51, P = 0.663), extent of CAD on angiography (OR = 1.18, 95%CI = 0.63-2.23, P = 0.605) and in-hospital mortality (RR = 1.08, 95%CI = 0.29-4.04, P = 0.908).

CONCLUSION

In contrast to previous reports, homozygosity for the Asp298 variant of the 894G>T polymorphism in the eNOS gene was not found to be associated with risk of AMI, extent of CAD and in-hospital mortality after AMI.

Endothelial nitric oxide synthase polymorphism (-786T->C) and increased risk of angiographic vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Vasospasm after aneurysmal subarachnoid hemorrhage (SAH) remains a leading cause of death and disability after aneurysm rupture. Decreased availability of nitric oxide (NO) may be crucial in its pathogenesis. We hypothesized that endothelial NO synthase (eNOS) polymorphisms may determine susceptibility to vasospasm in SAH patients.

METHODS

We conducted a prospective cohort study of SAH patients and determined vasospasm by cerebral angiography. We genotyped 3 eNOS polymorphisms: an intron 4 variable-number tandem-repeat, a promoter single-nucleotide polymorphism (-786T-->C SNP), and a coding SNP in exon 7 (894G-->T encoding E298D). Using multivariable logistic regression, we quantified the association of eNOS polymorphisms in patients with vasospasm confirmed by cerebral angiography.

RESULTS

For the eNOS promoter -786T-->C SNP, the presence of the CC genotype compared with any T genotype (CT or TT) was associated with increased odds of vasospasm (odds ratio=2.97, 95% CI=1.32 to 6.67, P=0.008). No association with vasospasm was observed for the eNOS 894G-->T or variable-number tandem-repeat polymorphisms.

CONCLUSIONS

These findings suggest that genetic variation influencing NO regulation contributes to the risk of angiographic vasospasm in patients with SAH. The specific role of the promoter SNP (-786T-->C) may determine the effect of NO regulated by this pathway, distinct from other known eNOS polymorphisms.

The mystery of coronary artery spasm

Coronary artery spasm is an important cause of chest pain and myocardial ischaemia. It can be defined as an exaggerated contractile response of epicardial coronary artery smooth muscle to various stimuli but the underlying mechanism is not well understood. Recent studies have shown that the loss of endothelial vasodilatory function in conjunction with an increase in vascular smooth muscle constrictor sensitivity to calcium are the likely predisposing conditions for coronary spasm. This review highlights current understanding of the pathophysiology, predisposing factors, diagnostic and therapeutic approaches for coronary spasm.

Endothelial nitric oxide synthase gene polymorphisms and cardiovascular disease: a HuGE review

This review examines the association of a subset of endothelial nitric oxide synthase gene (NOS3) polymorphisms (Glu298Asp, intron 4, and -786T>C) with cardiovascular disease. The Glu298Asp polymorphism within exon 7 is the only common nonsynonymous variant. The variants have been associated with low plasma nitric oxide concentrations and reduced vascular reactivity; difficulties in measuring those phenotypes means that their functional role remains unclear. A large meta-analysis of NOS3 polymorphisms in coronary heart disease revealed per-allele odds ratios of 1.17 (95% confidence interval: 1.07, 1.28) for Glu298Asp, 1.17 (95% confidence interval: 1.07, 1.28) for -786T>C, and 1.12 (95% confidence interval: 1.01, 1.24) for intron 4. However, there was evidence that small studies with more striking results could affect the associations of the Glu298Asp and -786T>C polymorphisms with coronary heart disease. Associations of NOS3 polymorphisms with hypertension, preeclampsia, stroke, and diabetes remain uncertain. To date, no reliable gene-gene or gene-environmental interactions have been described. Use of these variants in predictive testing is unlikely to be useful, although the population attributable fraction could be substantial if the modest associations are causal. The need for large-scale genetic association studies using tagging polymorphisms is warranted to confirm or refute a role of the NOS3 gene in coronary heart disease.

Nitric oxide and atherosclerosis: an update

Nitric oxide (NO) is a molecule that has gained recognition as a crucial modulator of vascular disease. NO has a number of intracellular effects that lead to vasorelaxation, endothelial regeneration, inhibition of leukocyte chemotaxis, and platelet adhesion. Endothelium damage induced by atherosclerosis leads to the reduction in bioactivity of endothelial NO synthase (eNOS) with subsequent impaired release of NO together with a local enhanced degradation of NO by increased generation of reactive oxygen species with subsequent cascade of oxidation-sensitive mechanisms in the arterial wall. Many commonly used vasculoprotective agents have their therapeutic actions through the production of NO. L-Arginine, the precursor of NO, has demonstrated beneficial effects in atherosclerosis and disturbed shear stress. Finally, eNOS gene polymorphism might be an additional risk factor that may contribute to predict cardiovascular events. However, further studies are needed to understand the possible clinical implications of these correlations.

Recent advances in the understanding of the role of nitric oxide in cardiovascular homeostasis

Nitric oxide synthases (NOS) are the enzymes responsible for nitric oxide (NO) generation. To date, 3 distinct NOS isoforms have been identified: neuronal NOS (NOS1), inducible NOS (NOS2), and endothelial NOS (NOS3). Biochemically, NOS consists of a flavin-containing reductase domain, a heme-containing oxygenase domain, and regulatory sites. NOS catalyse an overall 5-electron oxidation of one Nomega-atom of the guanidino group of L-arginine to form NO and L-citrulline. NO exerts a plethora of biological effects in the cardiovascular system. The basal formation of NO in mitochondria by a mitochondrial NOS seems to be one of the main regulators of cellular respiration, mitochondrial transmembrane potential, and transmembrane proton gradient. This review focuses on recent advances in the understanding of the role of enzyme and enzyme-independent NO formation, regulation of NO bioactivity, new aspects of NO on cardiac function and morphology, and the clinical impact and perspectives of these recent advances in our knowledge on NO-related pathways.

The GLU298ASP variant of nitric oxide synthase interacts with asymmetric dimethyl arginine in determining cardiovascular mortality in patients with end-stage renal disease

OBJECTIVES

Impaired nitric oxide generation and accumulation of the endogenous inhibitor of nitric oxide synthase (NOS), asymmetric dimethylarginine (ADMA), have been identified as strong predictors of cardiovascular outcomes in patients with end-stage renal disease (ESRD). We evaluated the role of endothelial NOS (eNOS) gene polymorphisms and its interaction with plasma ADMA in the high cardiovascular complications rate of these patients.

METHODS

The relationship between the Glu298Asp variant of eNOS and all-cause and cardiovascular mortality was assessed in a cohort study including 261 ESRD patients that were followed up for an average of 42 months.

RESULTS

During the follow-up period, 138 patients died, 81 of them (i.e. 59% of total deaths) of cardiovascular causes. On univariate Cox's regression analysis, eNOS genotype tended to be related to all-cause death but failed to reach formal statistical significance (P for trend=0.11). However, eNOS genotype showed a significant association with cardiovascular mortality in statistical models, including traditional risk factors and factors peculiar to ESRD, and became even stronger when plasma ADMA was forced into the Cox model (P=0.006). Furthermore, the risk of cardiovascular death was maximum in heterozygotes and homozygotes patients carrying the risk allele and in those having high ADMA levels (hazard ratio=2.71, 95% confidence interval 1.38-5.35, P=0.004) compared to those having just one of these two risk factors.

CONCLUSIONS

The T allele of the Glu298Asp polymorphism predicts cardiovascular mortality and interacts with plasma ADMA in determining this outcome in dialysis patients.

The G894T polymorphism on endothelial nitric oxide synthase gene is associated with premature coronary artery disease in a Turkish population

INTRODUCTION

The aim of the present study was to investigate the association between premature coronary artery disease and Glu298Asp polymorphism of the endothelial nitric oxide synthase gene.

MATERIALS AND METHODS

The eNOS gene polymorphism was analysed in 115 (mean age, 48.1+/-7.9 years) Turkish patients with a diagnosis of premature coronary artery disease and 83 (mean age, 44.6+/-1.4 years) control subjects. The Glu298Asp polymorphism of the endothelial nitric oxide synthase gene was determined by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

The patients group showed an increase in the frequency of the T allele compared to controls (0.456 versus 0.169, p=0.0001). There was a significant association between the TT genotype and premature coronary artery disease [eNOS TT vs. TG and GG; OR=17.000 (CI 95% 3.952-73.125, p=0.0001)]. The eNOS T/G genotypes were not associated with the number of affected vessels (p>0.05). In addition, the family history of premature coronary artery disease, smoking, diabetes, obesity, dyslipidemia and eNOS TT genotype were independent risk factors of coronary artery disease. The patients with eNOS TT genotype had 15 fold risk of coronary artery disease compared with the control group [OR=15.356(CI 95% 3.262-77.289, p=0.001)].

CONCLUSIONS

These results suggest that premature coronary artery disease is associated with the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene in our population.

Lack of association of eNOS (G894T) and p22phox NADPH oxidase subunit (C242T) polymorphisms with systemic sclerosis in a cohort of French Caucasian patients

OBJECTIVE

To assess the influence of endothelial nitric oxide synthase (eNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase polymorphisms on the susceptibility of patients to and clinical expression of systemic sclerosis (SSc).

METHODS

Seventy-seven French Caucasian patients with SSc were studied. Patients and ethnically matched controls (n=49) were genotyped, by restriction enzyme digestion of polymerase chain reaction (PCR) products, for G894T polymorphism in exon 7 of the eNOS gene and for C242T polymorphism of the gene encoding the p22(phox) NADPH oxidase subunit.

RESULTS

The allele and genotype frequencies of the polymorphisms did not differ between patients with SSc and the controls. Moreover, there was no association between these polymorphisms and disease phenotypes.

CONCLUSION

Our results indicate that eNOS (G894T) and p22(phox) (C242T) polymorphisms do not influence susceptibility to and the course of systemic sclerosis.

Nitric oxide insufficiency and atherothrombosis

Nitric oxide (NO) is a structurally simple compound that participates in a wide range of biological reactions to maintain normal endothelial function and an antithrombotic intravascular milieu. Among its principal effects are the regulation of vascular tone, vascular smooth muscle cell proliferation, endothelial-leukocyte interactions, and the antiplatelet effects of the endothelium. Impaired NO bioavailability represents the central feature of endothelial dysfunction, the earliest stage in the atherosclerotic process, and also contributes to the pathogenesis of acute vascular syndromes by predisposing to intravascular thrombosis. The causes of NO insufficiency can be grouped into two fundamental mechanisms: inadequate synthesis and increased inactivation of NO. Polymorphisms in the endothelial NO synthase gene and decreased substrate or cofactor availability for this enzyme are the main mechanisms that compromise the synthesis of NO. Inactivation of NO occurs mainly through its interaction with reactive oxygen species and can be favored by a deficiency of antioxidant enzymes such as glutathione peroxidase. In this review, we present an overview of NO synthesis and biological chemistry, discuss the mechanisms of action of NO in regulating endothelial and platelet function, and explore the causes of NO insufficiency, as well as the evidence linking these causes to the pathophysiology of endothelial dysfunction and atherothrombosis.