Association of eNOS gene polymorphisms T-786C and G894T with blood pressure variability in man

Erectile dysfunction in cardiovascular patients: A prospective study of the eNOS gene T-786C, G894T, and INTRON variable number of the tandem repeat functional interaction

BACKGROUND

Cardiovascular disease induces erectile dysfunction modulated by endothelial nitric oxide synthase enzyme and an impaired ejection fraction that restricts penis vascular congestion. However, the mechanisms regulating endothelial dysfunction are not understood.

OBJECTIVES

Exploring the functional impact of endothelial nitric oxide synthase genetic polymorphisms on erectile dysfunction and drug therapy optimization in high-risk cardiovascular disease patients.

MATERIALS AND METHODS

Patients with erectile dysfunction symptoms and candidates for andrology therapy were included (n = 112). Clinical data and endothelial nitric oxide synthase rs1799983 (G894T) and rs2070744 (T-786C), genotyped by fluorescence polarization assays, were registered. The 27-bp variable number of the tandem repeat polymorphism in intron 4 (intron4b/a) was analyzed by polymerase chain reaction-restriction fragment length polymorphism. Association analyses were run with the R-3.2.0 software.

RESULTS

A significant association between endothelial nitric oxide synthase 786-TT (p = 0.005) and the aa/ac of intron 4 variable number of the tandem repeat (p = 0.02) with higher erectile dysfunction susceptibility was observed in cardiovascular disease patients (60 ± 9 years, 66% severe erectile dysfunction, 56% ejection fraction). After 3-months of phosphodiesterase type 5 inhibitors, erectile dysfunction (International Index of Erectile Function, 50 ± 16 scores, the International Index of Erectile Function-Erectile Function 21 ± 10 scores, p < 0.001) and sexual quality of life (modified Sexual Life Quality Questionnaire 55 ± 23 scores, p < 0.001) had significantly improved. The cardiovascular ejection fraction was influenced positively with better sexual quality of life (0.1941), and also in the endothelial nitric oxide synthase G894-T allele (p = 0.076) carriers, which could merit future analyses. Erectile dysfunction was present as the primary clinical manifestation in 62% of cases, with cardiovascular disease occurring concurrently. Only former smokers and obese subjects debuted prior to cardiovascular disease than to erectile dysfunction.

CONCLUSIONS

Our study provides comprehensive insights into the functional interaction linking endothelial nitric oxide synthase gene polymorphisms, erectile function, and ejection fraction in high-risk cardiovascular disease patients. Future therapeutic strategies could target endothelial nitric oxide synthase activity by including lifestyle changes and epigenetic modulations.

Genes Predisposing to Erectile Dysfunction and Management: A Review

Background: The burden of erectile dysfunction (ED) is rising worldwide due to unresponsiveness of some affected individuals to existing drugs and treatment strategies. Fortunately, improvement in biological techniques has led to the understanding that some cases of the disorder may have a genetic etiology, which, when fully understood, may lead to improved treatment.

Objective: This review articulated established ED candidate genes and pathophysiology to assist researchers and medical practitioners to formulate effective drugs and treatment procedures.

Methods: The Google search engine was used to retrieve relevant information on the topic from reputable academic databases, including PubMed, Medline, Google Scholar, Scopus, and SpringerLink.

Results: The search discovered 10 ED candidate genes, which are SIM1, SLC6A4, 5-HTTLPR, TGFB1, DAT1, MC4R, NOS3, GNB3, AR, and MTHFR. Polymorphisms or mutations in these genes may disrupt erectile activities of the hypothalamus, neurotransmitters such as dopamine, serotonin, and nitric oxide as well as relaxation of penile tissues. Clinical presentations of ED include loss of erection, weak vaginal penetration, premature ejaculation, and anejaculation. Each gene has a distinct mechanism, which, if targeted in the affected may reverse the disorder or reduce the effects.

Conclusion: Some cases of ED are genetic, which, when fully understood, may give an insight into new treatment procedures or improve on the current ones. Medical practitioners are advised to formulate treatment procedures that target the affected gene (s) in individuals.

Endothelial Nitric Oxide Synthase Gene Polymorphisms (- 922A > G, - 786 T > C, Intron 4 b/a VNTR and 894 G > T) and Essential Hypertension: An Association Study with Haplotypes Analysis

Endothelial Nitric Oxide Synthase (eNOS) is an indispensable regulator of blood pressure through producing Nitric Oxide (NO). There is some evidence to suggest that eNOS gene polymorphisms are associated with Essential Hypertension (EHT). In this study, the potential association between eNOS 4a/4b, A922G, G894T, T786C gene polymorphisms and EHT as individual risk factors and as haplotypes are examined in the southern population of Iran (Bandar-Abbas). In this study, 200 EHT patients and 200 normotensive subjects which were matched for age and sex were included. Genotyping was performed by either utilizing Polymerase Chain Reaction (PCR) or PCR followed by Restriction Fragment length Polymorphism (RFLP) method. Our results demonstrated statistically significant associations between T786C, G894T, and 4a/4a and EHT (p < 0.05); however, A922G had no significant association with EHT (p > 0.05). Haplotype analysis also suggested that - 786C/- 922A/4a, - 786C/- 922A/4b and - 786C/- 922G/4a haplotypes were more frequent in EHT group than control group, hypothesizing a positive association with EHT. The present study has identified that the eNOS genetic variations are associated with EHT in southern population of Iran (Bandar-Abbas). These findings also suggested that a number of haplotypes of eNOS gene may be a driving factor for EHT susceptibility in respected population.

Endothelial nitric oxide synthase gene polymorphisms and erectile dysfunction in chronic pain

OBJECTIVES

To investigate whether endothelial nitric oxide synthase (eNOS) T786C, 4VNTR and G894 T gene polymorphisms could mediate in andrological treatment response in Spaniards.

SUBJECT PATIENTS/METHODS

The study participants were Spaniard males with erectile dysfunction (ED) and chronic pain (n = 105) recruited at the Pain Unit. eNOS polymorphisms were genotyped by quantitative polymerase chain reaction using Taqman specific probes. Statistical analyses were carried out using R-3.2.4 software.

RESULTS

A total of 69 patients required andrological treatment and 76% of them improved ED upon iPED5 (20%), testosterone (35%) or iPDE5/testosterone treatment (45%); being significantly better in T786C-CC patients. Multivariate regression analysis indicated that age, opioid daily dose and carriage of T786C-C allele influenced the risk and ED severity in Spaniard chronic pain patients.

CONCLUSION

T786C polymorphism at eNOS locus appeared to be a major contributor in the variable erectile function iPDE5/testosterone response in Spaniards.

The correlation between gene polymorphisms of endothelial nitric oxide synthase and aneurismal subarachnoid hemorrhage

To discuss the association of the T786C and G894T polymorphisms of endothelial nitric oxide synthase (eNOS) with the occurrence and prognosis of aneurismal subarachnoid hemorrhage (aSAH). One hundred sixty-nine patients with aSAH were collected as the case group, which was divided into the good prognosis group and adverse prognosis group according to the condition 3 months after the treatment. One hundred fifty-six healthy volunteers were collected as the control group. The allele and genotype of T786C and G894T polymorphisms of eNOS were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The genotype and allele frequency of eNOS were compared between different groups. And then, the risk factors of aSAH occurrence and prognosis were analyzed by using the logistic regression model. Both the genotype and allele frequency distributions of T786C and G894T between the case group and control group were significantly different (P < 0.05). There were significant differences in the distribution of G894T and T786C allele frequency and G894T genotype between the good prognosis group and adverse prognosis group, and there was no difference in T786C genotype. The results of the logistic regression analysis indicated that T786C and G894T polymorphisms of eNOS were independent influencing factors on the occurrence of aSAH and the G894T polymorphism was also closely related to the prognosis. T786C and G894T polymorphisms of eNOS gene were correlated with the occurrence and prognosis of aSAH, and the G894T polymorphism might be an independent influencing factor.

Association of endothelial nitric oxide synthase polymorphisms with an increased risk of erectile dysfunction

The purpose of our meta-analysis is to examine the associations between three single nucleotide polymorphisms of endothelial nitric oxide synthase (eNOS) gene, G894T, intron 4 and T-786C, and the risk of erectile dysfunction. An electronic database search was performed to identify case-control studies reporting the association between single nucleotide polymorphisms of eNOS gene and erectile dysfunction. Stringent inclusion and exclusion criteria were employed to select high-quality studies for this meta-analysis. Comprehensive Meta-analysis 2.0 software (Biostat Inc., Englewood, New Jersey, USA) was used for statistical analysis of the data extracted from the selected studies. From the initial 203 articles retrieved from database search, this meta-analysis finally selected 12 high-quality case-control studies that conformed to our inclusion criteria. The 12 studies contained a total of 1962 patients with erectile dysfunction and 1752 healthy controls. The results of our meta-analysis showed that G894T correlated with an increased risk erectile dysfunction under both the allele and dominant models (allele: OR = 1.556, 95% CI = 1.064–2.275, P = 0.023; dominant: OR = 1.613, 95% CI = 1.050–2.476, P = 0.029). A similar association was found between T-786C and erectile dysfunction under the allele model (OR = 1.679, 95% CI = 1.341–2.102, P < 0.001), but not under the dominant model (all P > 0.05). Our meta-analysis showed that the two single nucleotide polymorphisms in eNOS gene, G894T and T-786C, are strongly associated with the risk of erectile dysfunction.

Baroreflex Sensitivity in Children and Adolescents: Physiology, Hypertension, Obesity, Diabetes Mellitus

The increased prevalence of obesity in children and its complications have led to a greater interest in studying baroreflex sensitivity (BRS) in children. This review of BRS in children and adolescents includes subtopics on: 1. Resting values of BRS and their reproducibility, 2. Genetics of BRS, 3. The role of a primarily low BRS and obesity in the development of hypertension, and 4. Association of diabetes mellitus, BRS, and obesity. The conclusions specific to this age follow from this review: 1. The mean heart rate (HR) influences the measurement of BRS. Since the mean HR decreases during adolescence, HR should be taken into account. 2. A genetic dependency of BRS was found. 3. Low BRS values may precede pathological blood-pressure elevation in children with white-coat hypertension. We hypothesize that low BRS plays an active role in the emergence of hypertension in youth. A contribution of obesity to the development of hypertension was also found. We hypothesize that both factors, a primarily low BRS and obesity, are partially independent risk factors for hypertension in youths. 4. In diabetics, a low BRS compared to healthy children can be associated with insulin resistance. A reversibility of the BRS values could be possible after weight loss.

The relationship between blood pressure variability and Pooled Cohort Risk Assessment Equations 10-year cardiovascular risk score

BACKGROUND

Recent attention has focused on the clinical significance of blood pressure variability (BPV) in explaining the adverse cardiovascular consequences of hypertension. We therefore analyze the impact of 24 h BPV on the development of future cardiovascular disease determined by The Pooled Cohort Risk Assessment Equations 10-year risk calculator.

MATERIALS AND METHODS

We analyzed 250 adult patients, ages 40-80 years old. The ambulatory blood pressure monitoring was recorded automatically. We defined the mean blood pressure values, SD, and coefficient of variation (CV) of blood pressure on the basis of the recorded 24 h ambulatory blood pressure monitoring values as an indicator for BPV.Patients were divided into two groups according to their Pooled Cohort Risk Assessment Equations 10-year risk profile (<7.5 and ≥7.5%).

RESULTS

Besides the mean systolic blood pressure (SBP), parameters showing the BPV such as SD and CV of mean blood pressures were also significantly higher in patients with an elevated 10-year risk score compared with others. Only CV of SBP and pulse pressure showed a clear association with the 10-year risk in multivariate logistic regression analysis. The results suggested that each 1% increase in CV of SBP could lead to a 1.258-fold increase in The Pooled Cohort Risk Assessment Equations 10-year risk score.

CONCLUSION

In the present study, we found that independent of baseline SBP, increased CV of SBP within 24 h was associated with increased cardiovascular risk, as assessed by The Pooled Cohort Risk Assessment Equations 10-year risk calculator.

Relationship between cardiovascular health score and year-to-year blood pressure variability in China: a prospective cohort study

OBJECTIVES

On the basis of cardiovascular health factors and behaviours, the American Heart Association proposed the Cardiovascular Health Score (CHS). It has been widely used to estimate the cardiovascular health status of individuals. The aim of this study was to investigate the relationship between CHS and year-to-year blood pressure variability (BPV).

DESIGN

Prospective cohort study.

SETTINGS

We stratified participants into two groups by gender: first group, female group; second group, male group. The relationship between CHS and year-to-year blood pressure variability were analysed.

PARTICIPANTS

A total of 41,613 individuals met the inclusion criteria (no history of stroke, transient ischaemic attack, myocardial infarction, malignant tumour or atrial fibrillation) and had complete blood pressure data.

RESULTS

The coefficient of the variation of systolic blood pressure (SCV) was 8.33% in the total population and 8.68% and 8.22% in female and male groups, respectively (p<0.05). Multivariable linear regression analysis revealed that higher CHS was inversely associated with increasing year-to-year BPV, which persisted after adjusting for baseline systolic blood pressure and other risk factors. Each SD increase in CHS could lead to a 0.016SD decrease in SCV (p<0.05).

CONCLUSIONS

In summary, CHS was inversely related to year-to-year BPV, which suggested that a healthy lifestyle may contribute to better blood pressure management.

eNOS gene haplotype is indirectly associated with the recovery of cardiovascular autonomic modulation from exercise

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene decrease expression and activation of eNOS in vitro, which is associated with lower post-exercise increase in vasodilator reactivity in vivo. However, it is unknown whether such polymorphisms are associated with other eNOS-related phenotypes during recovery from exercise. Therefore, we investigated the impact of an eNOS haplotype containing polymorphic alleles at loci -786 and 894 on the recovery of cardiovascular autonomic function from exercise. Sedentary, non-obese, healthy subjects were enrolled [n = 107, age 32 ± 1 years (mean ± SEM)]. Resting autonomic modulation (heart rate variability, systolic blood pressure variability, and spontaneous baroreflex sensitivity) and vascular reactivity (forearm hyperemic response post-ischemia) were assessed at baseline, 10, 60, and 120 min after a maximal cardiopulmonary exercise test. Besides, autonomic function was assessed by heart rate recovery (HRR) immediately after peak exercise. Haplotype analysis showed that vagal modulation (i.e., HF n.u.) was significantly higher, combined sympathetic and vagal modulation (i.e., LF/HF) was significantly lower and total blood pressure variability was significantly lower post-exercise in a haplotype containing polymorphic alleles (H2) compared to a haplotype with wild type alleles (H1). HRR was similar between groups. Corroborating previous evidence, H2 had significantly lower post-exercise increase in vasodilator reactivity than H1. In conclusion, a haplotype containing polymorphic alleles at loci -786 and 894 had enhanced recovery of autonomic modulation from exercise, along with unchanged HRR, and attenuated vasodilator reactivity. Then, these results suggest an autonomic compensatory response of a direct deleterious effect of eNOS polymorphisms on the vascular function.

From the First Spectral Analysis of Blood Pressure Variability in the World to the Present Time: Contribution of the Department of Physiology of the Faculty of Medicine, Masaryk University, Brno

The review shows the significance of blood pressure regulation studies conducted during several decades at the Department of Physiology, Faculty of Medicine, Masaryk University, Brno. Continuous non-invasive blood pressure measurement was first introduced and patented here and, with the obtained data, the first spectral analysis of blood pressure was performed. This method was used in many different physiological studies on the relationship of blood pressure regulation to circulatory parameters, breathing, and baroreflex sensitivity. The article deals with studies on risk stratification of sudden cardiac death according to decreased baroreflex sensitivity, 24-hour heart rate variability, the amount of extrasystoles and late potentials. Importance of the new method of determination of one summation risk index is described here. A summary of the new conception of the relationship between low baroreflex sensitivity and hypertension is presented. Here, not only pathological changes of the vessel wall but also increased sympathetic activity and genetic predisposition play a role. Importance of studies conducted in young adults is highlighted, as inherited BRS decrease contributes to earlier blood pressure increase in the young. This research is highly topical, since prevention of hypertension in childhood is possible. Recent studies are dedicated to blood pressure regulation in young diabetics.

Assessment and management of blood-pressure variability

Blood pressure (BP) is characterized by marked short-term fluctuations occurring within a 24 h period (beat-to-beat, minute-to-minute, hour-to-hour, and day-to-night changes) and also by long-term fluctuations occurring over more-prolonged periods of time (days, weeks, months, seasons, and even years). Rather than representing 'background noise' or a randomly occurring phenomenon, these variations have been shown to be the result of complex interactions between extrinsic environmental and behavioural factors and intrinsic cardiovascular regulatory mechanisms. Although the adverse cardiovascular consequences of hypertension largely depend on absolute BP values, evidence from observational studies and post-hoc analyses of data from clinical trials have indicated that these outcomes might also depend on increased BP variability (BPV). Increased short-term and long-term BPV are associated with the development, progression, and severity of cardiac, vascular, and renal damage and with an increased risk of cardiovascular events and mortality. Of particular interest are the findings from post-hoc analyses of large intervention trials in hypertension, showing that within-patient visit-to-visit BPV is strongly prognostic for cardiovascular morbidity and mortality. This result has prompted discussion on whether antihypertensive treatment should be targeted not only towards reducing mean BP levels but also to stabilizing BPV with the aim of achieving consistent BP control over time, which might favour cardiovascular protection.