Race and sex differences in cardiovascular α-adrenergic and β-adrenergic receptor responsiveness in men and women with high blood pressure

The effect of endothelin a receptor inhibition and biological sex on cutaneous microvascular function in non-Hispanic Black and White young adults

The purpose of this study was to investigate whether endothelin-A receptor (ETAR) inhibition in non-Hispanic Black (NHB) and White (NHW) young adults depends on biological sex. We recruited females during low hormone (n = 22) and high hormone (n = 22) phases, and males (n = 22). Participants self-identified as NHB (n = 33) or NHW (n = 33). Participants were instrumented with two microdialysis fibers: (1) lactated Ringer's (control) and (2) 500 nM BQ-123 (ETAR antagonist). Local heating was used to elicit cutaneous vasodilation, and an infusion of 20 mM L-NAME to quantify NO-dependent vasodilation. At control sites, NO-dependent vasodilation was lowest in NHB males (46 ± 13 %NO) and NHB females during low hormone phases (47 ± 12 %NO) compared to all NHW groups. Inhibition of ETAR increased NO-dependent vasodilation in NHB males (66 ± 13 %NO), in both groups of females during low hormone phases (NHW, control: 64 ± 12 %NO, BQ-123: 85 ± 11 %NO; NHB, BQ-123: 68 ± 13 %NO), and in NHB females during high hormone phases (control: 61 ± 11 %NO, BQ-123: 83 ± 9 %NO). There was no effect for ETAR inhibition in NHW males or females during high hormone phases. These data suggest the effect of ETAR inhibition on NO-dependent vasodilation is influenced by biological sex and racial identity.

Addressing Cardiovascular Risk Across the Arc of a Woman's Life: Sex-Specific Prevention and Treatment

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in women in the United States of America. Despite this, women are underdiagnosed, less often receive preventive care, and are undertreated for CVD compared to men. There has been an increase in sex-specific risk factors and treatments over the past decade; however, sex-specific recommendations have not been included in the guidelines. We aim to highlight recent evidence behind the differential effect of traditional risk factors and underscore sex-specific risk factors with an intention to promote awareness, improve risk stratification, and early implementation of appropriate preventive therapies in women.

RECENT FINDINGS

Women are prescribed fewer antihypertensives and lipid-lowering agents and receive less cardiovascular care as compared to men. Additionally, pregnancy complications have been associated with increased cardiovascular mortality later in life. Findings from the ARIC study suggest that there is a perception of lower risk of cardiovascular disease in women. The SWEDEHEART study which investigated sex differences in treatment, noted a lower prescription of guideline-directed therapy in women. Women are less likely to be prescribed statin medications by their providers in both primary and secondary prevention as they are considered lower risk than men, while also being more likely to decline and discontinue treatment. A woman's abnormal response to pregnancy may serve as her first physiological stress test which can have implications on her future cardiovascular health. This was supported by the CHAMPs study noting a higher premature cardiovascular risk after maternal complications. Adverse pregnancy outcomes have been associated with a 1.5-4.0 fold increase in future cardiovascular events in multiple studies. In this review, we highlight the differences in traditional risk factors and their impact on women. Furthermore, we address the sex-specific risk factors and pregnancy-associated complications that increase the risk of CVD in women. Adherence to GDMT may have implications on overall mortality in women. An effort to improve early recognition of CVD risk with implementation of aggressive risk factor control and lifestyle modification should be emphasized. Future studies should specifically report on differences in outcomes between males and females. Increased awareness and knowledge on sex-specific risks and prevention are likely to lower the prevalence and improve outcomes of CVD in women.

Endothelin A receptor inhibition increases nitric oxide-dependent vasodilation independent of superoxide in non-Hispanic Black young adults

Young non-Hispanic Black adults have reduced microvascular endothelial function compared with non-Hispanic White counterparts, but the mechanisms are not fully elucidated. The purpose of this study was to investigate the effect of endothelin-1 A receptor (ET_AR) and superoxide on cutaneous microvascular function in young non-Hispanic Black (n = 10) and White (n = 10) adults. Participants were instrumented with four intradermal microdialysis fibers: 1) lactated Ringer's (control), 2) 500 nM BQ-123 (ET_AR antagonist), 3) 10 μM tempol (superoxide dismutase mimetic), and 4) BQ-123 + tempol. Skin blood flow was assessed via laser-Doppler flowmetry (LDF), and each site underwent rapid local heating from 33°C to 39°C. At the plateau of local heating, 20 mM l-NAME [nitric oxide (NO) synthase inhibitor] was infused to quantify NO-dependent vasodilation. Data are means ± standard deviation. NO-dependent vasodilation was decreased in non-Hispanic Black compared with non-Hispanic White young adults (P < 0.01). NO-dependent vasodilation was increased at BQ-123 sites (73 ± 10% NO) and at BQ-123 + tempol sites (71 ± 10%NO) in non-Hispanic Black young adults compared with control (53 ± 13%NO, P = 0.01). Tempol alone had no effect on NO-dependent vasodilation in non-Hispanic Black young adults (63 ± 14%NO, P = 0.18). NO-dependent vasodilation at BQ-123 sites was not statistically different between non-Hispanic Black and White (80 ± 7%NO) young adults (P = 0.15). ET_AR contributes to reduced NO-dependent vasodilation in non-Hispanic Black young adults independent of superoxide, suggesting a greater effect on NO synthesis rather than NO scavenging via superoxide.NEW & NOTEWORTHY Endothelin-1 A receptors (ET_ARs) have been shown to reduce endothelial function independently and through increased production of superoxide. We show that independent ET_AR inhibition increases microvascular endothelial function in non-Hispanic Black young adults. However, administration of a superoxide dismutase mimetic alone and in combination with ET_AR inhibition had no effect on microvascular endothelial function suggesting that, in the cutaneous microvasculature, the negative effects of ET_AR in non-Hispanic Black young adults are independent of superoxide production.

Racial differences in sympathetic nervous system indicators: Implications and challenges for research

Growing evidence indicates the presence of racial differences in sympathetic nervous system (SNS) functioning, yet the nature of these differences is unclear and appears to vary across different indices of SNS activity. Moreover, racial differences among commonly used indices of SNS activity are under-investigated. This systematic review examines racial differences among widely used resting SNS indices, such as electrodermal activity (EDA), pre-ejection period (PEP), and salivary alpha-amylase (sAA). Our review reveals that Black participants have consistently been found to display lower resting EDA compared to White participants. The few studies that have investigated or reported racial differences in PEP and sAA yield mixed findings about whether racial differences exist. We discuss potential reasons for racial differences in SNS activity, such as index-specific factors, lab confounds, psychosocial environmental factors, and their interactions. We outline a framework characterizing possible contributors to racial differences in SNS functioning. Lastly, we highlight the implications of several definitional, analytic, and interpretive issues concerning the treatment of group differences in psychophysiological activity and provide future recommendations.

Menopause-associated risk of cardiovascular disease

Cardiovascular disease (CVD) is of major concern in women entering menopause. The changing hormonal milieu predisposes them to increased CVD risk, due to a constellation of risk factors, such as visceral obesity, atherogenic dyslipidemia, dysregulation in glucose homeostasis, non-alcoholic fatty liver disease and arterial hypertension. However, an independent association of menopause per se with increased risk of CVD events has only been proven for early menopause (<45 years). Menopausal hormone therapy (MHT) ameliorates most of the CVD risk factors mentioned above. Transdermal estrogens are the preferable regimen, since they do not increase triglyceride concentrations and they are not associated with increased risk of venous thromboembolic events (VTE). Although administration of MHT should be considered on an individual basis, MHT may reduce CVD morbidity and mortality, if commenced during the early postmenopausal period (<60 years or within ten years since the last menstrual period). In women with premature ovarian insufficiency (POI), MHT should be administered at least until the average age of menopause (50-52 years). MHT is contraindicated in women with a history of VTE and is not currently recommended for the sole purpose of CVD prevention. The risk of breast cancer associated with MHT is generally low and is mainly conferred by the progestogen. Micronized progesterone and dydrogesterone are associated with lower risk compared to other progestogens.

Sex Differences in Cardiovascular Consequences of Hypertension, Obesity, and Diabetes: JACC Focus Seminar 4/7

It has long been recognized that there are significant differences between the sexes affecting prevalence, incidence, and severity over a broad range of diseases. Until the early 1990s, the limited research conducted on women's health focused primarily on diseases affecting fertility and reproduction, and women were excluded from most clinical trials. For these reasons, the prevention, diagnosis, and treatment of serious chronic diseases such as cardiovascular disease in women continue to be based primarily on findings in men, and sex-specific clinical guidelines are mostly lacking. Hypertension, obesity, and diabetes, interrelated risk factors for cardiovascular disease, differ by sex in terms of prevalence and adverse effects as well as by genetics and biology. Research is needed to understand sex differences in hypertension, obesity, and diabetes to optimally inform sex-specific prevention, diagnosis, and treatment strategies for women and men. In this way, sex-specific clinical guidelines can be developed where warranted.

Alpha-Adrenergic Mechanisms in the Cardiovascular Hyperreactivity to Norepinephrine-Infusion in Essential Hypertension

AIMS

Essential hypertension (EHT) is characterized by cardiovascular hyperreactivity to stress but underlying mechanism are not fully understood. Here, we investigated the role of α-adrenergic receptors (α-AR) in the cardiovascular reactivity to a norepinephrine (NE)-stress reactivity-mimicking NE-infusion in essential hypertensive individuals (HT) as compared to normotensive individuals (NT).

METHODS

24 male HT and 24 male NT participated in three experimental trials on three separate days with a 1-min infusion followed by a 15-min infusion. Trials varied in infusion-substances: placebo saline (Sal)-infusions (trial-1:Sal+Sal), NE-infusion without (trial-2:Sal+NE) or with non-selective α-AR blockade by phentolamine (PHE) (trial-3:PHE+NE). NE-infusion dosage (5µg/ml/min) and duration were chosen to mimic duration and physiological effects of NE-release in reaction to established stress induction protocols. We repeatedly measured systolic (SBP) and diastolic blood pressure (DBP) as well as heart rate before, during, and after infusions.

RESULTS

SBP and DBP reactivity to the three infusion-trials differed between HT and NT (p's≤.014). HT exhibited greater BP reactivity to NE-infusion alone compared to NT (trial-2-vs-trial-1: p's≤.033). Group differences in DBP reactivity to NE disappeared with prior PHE blockade (trial-3: p=.26), while SBP reactivity differences remained (trial-3: p=.016). Heart rate reactivity to infusion-trials did not differ between HT and NT (p=.73).

CONCLUSION

Our findings suggest a mediating role of α-AR in DBP hyperreactivity to NE-infusion in EHT. However, in SBP hyperreactivity to NE-infusion in EHT, the functioning of α-AR seems impaired suggesting that the SBP hyperreactivity in hypertension is not mediated by α-AR.

Differential influences of dietary sodium on blood pressure regulation based on race and sex

There are clear differences between men and women, and differences among races, in the incidence and prevalence of hypertension. Furthermore, there is extensive inter-individual variability among humans in the extent to which sodium ingestion alters blood pressure. Orthostatic intolerance and orthostatic hypotension are more common in women; these are often treated with a high salt diet, which has variable efficacy in increasing blood volume and blood pressure. Conversely, people with certain forms of hypertension are often counseled to decrease their sodium intake. Non-Hispanic Black men and women have higher rates of hypertension compared to non-Hispanic White men and women and other racial/ethnic groups. In aggregate, Black women appear to have better orthostatic tolerance than White women. In the present paper, we summarize and evaluate the current evidence for mechanisms of blood pressure regulation in men and women, as well as differences between Black and White groups, with a focus on cardiovascular responses to salt and differences among these groups. We also provide a brief review of factors that are not traditionally considered to be "biological" - such as socio-economic disparities resulting from historic and contemporary inequity across racial groups. These non-biological factors have direct and substantial influences on cardiovascular mechanisms, as well as implications for the influences of salt and sodium intake on blood pressure and cardiovascular health. We conclude that both biological and socio-economic factors provide critical modulating influences when considering the impacts of sodium on cardiovascular health as functions of race and sex.

Exposure to volatile organic compounds - acrolein, 1,3-butadiene, and crotonaldehyde - is associated with vascular dysfunction

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality worldwide. Exposure to air pollution, specifically particulate matter of diameter ≤2.5 μm (PM2.5), is a well-established risk factor for CVD. However, the contribution of gaseous pollutant exposure to CVD risk is less clear.

OBJECTIVE

To examine the vascular effects of exposure to individual volatile organic compounds (VOCs) and mixtures of VOCs.

METHODS

We measured urinary metabolites of acrolein (CEMA and 3HPMA), 1,3-butadiene (DHBMA and MHBMA3), and crotonaldehyde (HPMMA) in 346 nonsmokers with varying levels of CVD risk. On the day of enrollment, we measured blood pressure (BP), reactive hyperemia index (RHI - a measure of endothelial function), and urinary levels of catecholamines and their metabolites. We used generalized linear models for evaluating the association between individual VOC metabolites and BP, RHI, and catecholamines, and we used Bayesian Kernel Machine Regression (BKMR) to assess exposure to VOC metabolite mixtures and BP.

RESULTS

We found that the levels of 3HPMA were positively associated with systolic BP (0.98 mmHg per interquartile range (IQR) of 3HPMA; CI: 0.06, 1.91; P = 0.04). Stratified analysis revealed an increased association with systolic BP in Black participants despite lower levels of urinary 3HPMA. This association was independent of PM2.5 exposure and BP medications. BKMR analysis confirmed that 3HPMA was the major metabolite associated with higher BP in the presence of other metabolites. We also found that 3HPMA and DHBMA were associated with decreased endothelial function. For each IQR of 3HPMA or DHBMA, there was a -4.4% (CI: -7.2, -0.0; P = 0.03) and a -3.9% (CI: -9.4, -0.0; P = 0.04) difference in RHI, respectively. Although in the entire cohort the levels of several urinary VOC metabolites were weakly associated with urinary catecholamines and their metabolites, in Black participants, DHBMA levels showed strong associations with urinary norepinephrine and normetanephrine levels.

DISCUSSION

Exposure to acrolein and 1,3-butadiene is associated with endothelial dysfunction and may contribute to elevated risk of hypertension in participants with increased sympathetic tone, particularly in Black individuals.

α-Adrenergic receptor blockade attenuates pressor response during mental stress in young black adults

Black individuals exhibit increased blood pressure (BP) responses to sympathetic stimulation that are associated with an increased risk of hypertension (HTN). We tested the hypothesis that α1 -adrenergic blockade inhibits the increased BP response during and after 45-min stress in young normotensive Black adults, which may be mediated, in part, by dampened vasoconstriction and decreased renal sodium retention. Utilizing a double-masked randomized, crossover study design, 51 normotensive Black adults (31 ± 8 yr) were treated with either a placebo or 1 mg/day of prazosin for 1 week. On the final day of each treatment, hemodynamic measures and urinary sodium excretion (UNaV) were collected before (Rest), during (Stress) and after (Recovery) 45 min of mental stress induced via a competitive video game task. During the Stress period, diastolic BP and total peripheral resistance (TPR) were significantly lower with prazosin compared to placebo (p < .05 for both). Similarly, we observed lower systolic BP, diastolic BP, and TPR during the Recovery period with prazosin versus placebo (p < .05 for both). There was no effect of prazosin on stress-associated UNaV. The change in systolic BP from Rest to Recovery was positively associated with the change in TPR with both treatments (p < .05 for both). In summary, prazosin treatment dampened BP reactivity to 45-min mental stress and lowered post-stress BP over the recovery period, which was linked to reduce TPR in young normotensive Black adults. These results suggest that α1 -adrenergic receptor activity may contribute to BP responses and delayed BP recovery to prolonged mental stress through increased vasoconstriction in Black adults.

Race and sex differences in cardiovascular autonomic regulation

Racial and ethnic differences in cardiovascular morbidity and mortality persist despite advances in risk factor identification and implementation of evidence-based treatment strategies. African American men and women are disproportionately affected by cardiovascular risk factors, particularly hypertension. In this context, previous studies have identified sex and racial differences in autonomic cardiovascular regulation which may contribute to the development of hypertension and its high morbidity burden among African Americans. In this review, we provide a comprehensive evaluation of the potential pathophysiological mechanisms of blood pressure control and their differences based on sex and race. These mechanisms include obesity-induced sympathetic activation, sympatho-vascular transduction, baroreflex sensitivity and adrenoreceptor vascular sensitivity, which have been the subjects of prior investigation in this field. Understanding the racial differences in the pathophysiology of hypertension and its co-morbid conditions would allow us to implement better treatment strategies tailored to African Americans, with the ultimate goal of reducing cardiovascular mortality in this population.

Influence of sex on heightened vasoconstrictor mechanisms in the non-Hispanic black population

Cardiovascular disease (CVD) affects individuals of all races and ethnicities; however, its prevalence is highest in non-Hispanic black individuals (BL) relative to other populations. While previous research has provided valuable insight into elevated CVD risk in the BL population, this work has been almost exclusively conducted in men. This is alarming given that BL women suffer from CVD at an equivalent rate to BL men and each has a greater prevalence when compared to all other ethnicities, regardless of sex. The importance of investigating sex differences in mechanisms of cardiovascular function is highlighted by the National Institute of Health requiring sex to be considered as a biological variable in research studies to better our "understanding of key sex influences on health processes and outcomes." The mechanism(s) responsible for the elevated CVD risk in BL women remains unclear and is likely multifactorial. Limited studies in BL women suggest that, while impaired vasodilator capacity is involved, heightened vasoconstrictor tone and/or responsiveness may also contribute. Within this mini-review, we will discuss potential mechanisms of elevated rates of hypertension and other CVDs in BL individuals with a particular focus on young, otherwise healthy, college-aged women. To stimulate academic thought and future research, we will also discuss potential mechanisms for impaired vascular function in BL women, as well as possible divergent mechanisms between BL men and women based on either preliminary data or plausible speculation extending from findings in the existing literature. Last, we will conclude with potential future research directions aimed at better understanding the elevated risk for hypertension and CVD in BL women.

Influence of Sex and Age on Muscle Sympathetic Nerve Activity of Healthy Normotensive Adults

As with blood pressure, age-related changes in muscle sympathetic nerve activity (MSNA) may differ nonlinearly between sexes. Data acquired from 398 male (age: 39±17; range: 18-78 years [mean±SD]) and 260 female (age: 37±18; range: 18-81 years) normotensive healthy nonmedicated volunteers were analyzed using linear regression models with resting MSNA burst frequency as the outcome and the predictors sex, age, MSNA, blood pressure, and body mass index modelled with natural cubic splines. Age and body mass index contributed 41% and 11%, respectively, of MSNA variance in females and 23% and 1% in males. Overall, changes in MSNA with age were sigmoidal. At age 20, mean MSNA of males and females were similar, then diverged significantly, reaching in women a nadir at age 30. After 30, MSNA increased nonlinearly in both sexes. Both MSNA discharge and blood pressure were lower in females until age 50 (17±9 versus 25±10 bursts·min^-1; P<1×10^-19; 106±11/66±8 versus 116±7/68±9 mm Hg; P<0.01) but converged thereafter (38±11 versus 35±12 bursts·min^-1; P=0.17; 119±15/71±13 versus 120±13/72±9 mm Hg; P>0.56). Compared with age 30, MSNA burst frequency at age 70 was 57% higher in males but 3-fold greater in females; corresponding increases in systolic blood pressure were 1 (95% CI, -4 to 5) and 12 (95% CI, 6-16) mm Hg. Except for concordance in females beyond age 40, there was no systematic change with age in any resting MSNA-blood pressure relationship. In normotensive adults, MSNA increases after age 30, with ascendance steeper in women.

Vascular α1-Adrenergic Receptor Responsiveness in Masked Hypertension

BACKGROUND

Masked hypertension (nonhypertensive in the clinic setting but hypertensive outside the clinic during wakefulness) is characterized by increased blood pressure in response to physical and emotional stressors that activate the sympathetic nervous system (SNS). However, no studies have assessed vascular reactivity to a pharmacological SNS challenge in individuals with masked hypertension.

METHODS

We analyzed data from 161 adults aged 25 to 45 years (mean ± standard deviation age 33 ± 6 years; 48% were African American and 43% were female). Participants completed ambulatory blood pressure monitoring, and a standardized α 1-adrenergic agonist phenylephrine test that determines the dose of phenylephrine required to increase a participant's mean arterial pressure by 25 mm Hg (PD25).

RESULTS

Twenty-one participants were considered to have masked hypertension (clinic systolic blood pressure (SBP) <140 and diastolic blood pressure (DBP) <90 mm Hg but awake SBP ≥135 or DBP ≥85 mm Hg), 28 had sustained hypertension (clinic SBP ≥140 or DBP ≥90 mm Hg and awake SBP ≥135 or DBP ≥85 mm Hg), and 106 had sustained normotension (clinic SBP <140 and DBP <90 mm Hg and awake SBP <135 and DBP <85 mm Hg). After multivariable adjustment, the mean (±SE) PD25 was less in participants with masked hypertension compared with their counterparts with sustained normotension (222.1 ± 33.2 vs. 328.7 ± 15.0; P = 0.012), but similar to that observed in subjects with sustained hypertension (254.8 ± 31.0; P =0.12).

CONCLUSIONS

Among young and middle-aged adults, masked hypertension is associated with increased vascular reactivity to a SNS challenge, which may contribute to elevated awake BPs as well as to increased cardiovascular disease risk.

Lack of sexual dimorphism in a mouse model of isoproterenol-induced cardiac dysfunction

Sex-related differences in cardiovascular diseases are highly complex in humans and model-dependent in experimental laboratory animals. The objective of this work was to comprehensively investigate key sex differences in the response to acute and prolonged adrenergic stimulation in C57Bl/6NCrl mice. Cardiac function was assessed by trans-thoracic echocardiography before and after acute adrenergic stimulation (a single sub-cutaneous dose of isoproterenol 10 mg/kg) in 15 weeks old male and female C57Bl/6NCrl mice. Thereafter, prolonged adrenergic stimulation was achieved by sub-cutaneous injections of isoproterenol 10 mg/kg/day for 14 days in male and female mice. Cardiac function and morphometry were assessed by trans-thoracic echocardiography on the 15th day. Thereafter, the mice were euthanized, and the hearts were collected. Histopathological analysis of myocardial tissue was performed after staining with hematoxylin & eosin, Masson's trichrome and MAC-2 antibody. Gene expression of remodeling and fibrotic markers was assessed by real-time PCR. Cardiac function and morphometry were also measured before and after isoproterenol 10 mg/kg/day for 14 days in groups of gonadectomized male and female mice and sham-operated controls. In the current work, there were no statistically significant differences in the positive inotropic and chronotropic effects of isoproterenol between male and female C57Bl/6NCrl. After prolonged adrenergic stimulation, there was similar degree of cardiac dysfunction, cardiac hypertrophy, and myocardial fibrosis in male and female mice. Similarly, prolonged isoproterenol administration induced hypertrophic and fibrotic genes in hearts of male and female mice to the same extent. Intriguingly, gonadectomy of male and female mice did not have a significant impact on isoproterenol-induced cardiac dysfunction as compared to sham-operated animals. The current work demonstrated lack of significant sex-related differences in isoproterenol-induced cardiac hypertrophy, dysfunction, and fibrosis in C57Bl/6NCrl mice. This study suggests that female sex may not be sufficient to protect the heart in this model of isoproterenol-induced cardiac dysfunction and underscores the notion that sexual dimorphism in cardiovascular diseases is highly model-dependent.

Early menopause is associated with increased risk of arterial hypertension: A systematic review and meta-analysis

OBJECTIVE

Menopausal transition has been associated with an increased risk of cardiovascular disease (CVD), mainly attributed to atherogenic dyslipidaemia, central obesity and insulin resistance. Whether arterial hypertension (AH) also contributes to menopause-associated CVD is currently unknown. The aim of this study was to systematically investigate and meta-analyze the best available evidence regarding the association between early menopause (EM) and AH risk.

METHODS

A comprehensive search was conducted in PubMed, CENTRAL and Scopus databases, up to January 20th, 2020. Data were expressed as odds ratio (OR) with 95 % confidence intervals (CI). The I² index was employed for heterogeneity.

RESULTS

Ten studies were included in the quantitative analysis (273,994 postmenopausal women, 76853 cases with AH). Women with EM (age at menopause <45 years) were at higher AH risk compared with those of normal age at menopause (>45 years) (OR 1.10, 95 % CI 1.01-1.19, p = 0.03; I² 79 %). The direction or the magnitude of this association remained significant when the analysis was restricted to studies including groups matched for potential confounders, such as age, BMI, smoking or the use of menopausal hormone therapy or oral contraceptives.

CONCLUSIONS

Women with EM have an increased risk for AH compared with those of normal age at menopause.

Racial disparities in cardiovascular disease risk: mechanisms of vascular dysfunction

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

Sex differences in antihypertensive drug use and blood pressure control

BACKGROUND

Hypertension is the most important modifiable cardiovascular risk factor. Epidemiological studies have shown the benefits of lowering blood pressure (BP), but BP control is a major challenge. Furthermore, there are significant sex differences in antihypertensive drug use and BP control. This study examined sex differences in antihypertensive drug use and BP control, with the aim of reducing the complications of hypertension and improving quality of life.

METHODS

The study was performed in our outpatient hypertension clinic, and included 1529 patients without secondary hypertension or comorbidities. The study, investigated BP control rates and patterns of antihypertensive drug use in male and female. All data were collected using structured questionnaires and patient measurements.

RESULTS

The study included 713 males and 816 females in this study. Fewer females had hypertension in the younger age group (16.2% vs 11.6%; p>0.05), but this difference disappeared in middle-aged (47.8% vs 49.9 %; p<0.05) and elderly age groups (36.0% vs 38.5%; p<0.05). BP control rates differed between males and females (35.6% in male, 31.9% in female, p<0.01). There was an overall difference in BP control rates between males and females (35.6% in males, 31.9% in females, p<0.01). In this aged 18-44 years, angiotensin converting enzyme inhibitors (ACEIs) showed the best control rate in males, while calcium channel blockers (CCBs) were least effective (61.5% with ACEIs, 28.6% with CCBs; p<0.05). In this aged 45-64 years, diuretics (DUs) showed the best control rate in females, while CCBs were least effective (47.5% with DUs, 28.3% with CCBs; p<0.05).

CONCLUSIONS

Sex plays an important role in BP control. In those aged 18-44 years, males using ACEIs showed best control rates. In those aged 45-64 years, females using DUs showed best control rates. Our study provides a basis with the selection of antihypertensive drugs according to sex and age.

Circadian hemodynamics in men and women with high blood pressure: dipper vs. nondipper and racial differences

OBJECTIVE

The 'nondipping' pattern of circadian blood pressure (BP) variation is an established independent predictor of adverse cardiovascular outcomes. Although this phenomenon has been widely studied, its underlying circadian hemodynamics of cardiac output and systemic vascular resistance (SVR) have not been well characterized. We evaluated the hypothesis that BP nondipping would be associated with a blunted night-time reduction in SVR in a biracial sample of 140 (63 African-American and 77 white) men and women with elevated clinic BP (130-159/85-99 mmHg).

METHODS AND RESULTS

Twenty-four-hour ambulatory hemodynamics were assessed using standard ambulatory BP monitoring coupled with synchronized ambulatory impedance cardiography. Using the criterion of less than 10% dip in SBP, there were 51 nondippers (SBP dip = 7.3 ± 2.6%) and 89 dippers (SBP dip = 15.5 ± 3.4%). There was minimal change in cardiac output from daytime to night-time in both dippers and nondippers. However, SVR decreased from daytime to night-time, but nondippers compared with dippers exhibited a significantly attenuated decrease in SVR from daytime to night-time (7.8 vs. 16.1%, P < 0.001). Relative to their white counterparts, African-Americans also exhibited blunted SBP dipping (10.9 vs. 14.6%, P < 0.001) as well as an attenuated decrease in SVR (10.8 vs. 15.6%, P < 0.001).

CONCLUSION

Overall, these findings indicate that blunted night-time BP dipping is associated with impairment of the systemic vasodilation that is characteristic of the night-time sleep period and is especially prominent among African-Americans. In the context of high BP, these findings suggest that nondipping may be a manifestation, or marker, of more advanced vascular disease.

Genomics of Cardiovascular Measures of Autonomic Tone

The autonomic nervous system exerts broad control over the involuntary functions of the human body through complex equilibrium between sympathetic and parasympathetic tone. Imbalance in this equilibrium is associated with a multitude of cardiovascular outcomes, including mortality. The cardiovascular static state of this equilibrium can be quantified using physiological parameters such as heart rate (HR), blood pressure, and by spectral analysis of HR variability. Here, we review the current state of knowledge of the genetic background of cardiovascular measurements of autonomic tone. For most parameters of autonomic tone, a large portion of variability is explained by genetic heritability. Many of the static parameters of autonomic tone have also been studied through candidate-gene approach, yielding some insight into how genotypes of adrenergic receptors affect variables such as HR. Genome-wide approaches in large cohorts similarly exist for static variables such as HR and blood pressure but less is known about the genetic background of the dynamic and more specific measurements, such as HR variability. Furthermore, because most autonomic measures are likely polygenic, pathway analyses and modeling of polygenic effects are critical. Future work will hopefully explain the control of autonomic tone and guide individualized therapeutic interventions.

Gender differences in hypertension

PURPOSE OF REVIEW

The review is a short discussion of sex/gender differences in blood pressure control with a focus on gender differences in hypertension awareness, prevalence, and treatment, the new American College of Cardiology/American Heart Association Guidelines, and recent discoveries in animal models and humans on mechanisms responsible for sex/gender differences in hypertension.

RECENT FINDINGS

Hypertension awareness is greater in women than men, the prevalence of hypertension is higher in men than women until after menopause, and although the American College of Cardiology/American Heart Association Guidelines recommend similar treatment for men and women, this is not currently the case in practice. New studies into mechanisms responsible for sex/gender differences in hypertension include the role of the kidneys, the renin-angiotensin system, relaxin, and developmental programming.

SUMMARY

Specific guidelines for hypertension treatment in women and men have yet to be developed. However, numerous animal and human studies have shown differences in the mechanisms responsible for blood pressure control between the sexes. Thus more research into the sex/gender differences in mechanisms responsible for hypertension are needed to determine the best treatment options that will reduce the risk of hypertension and subsequent cardiovascular diseases in both genders.

The Quest for Type 2 Diabetes Subgroups Identification: Literature Review for a New Subtype Proposal

Type 2 diabetes is considered typically as a heterogeneous disease that englobes the potential different subtypes with distinct pathophysiological mechanisms and/or susceptibility to complications. Some authors have succeeded in the identification of some of these subgroups, but a lot of work remains to be completed. Given the effects of the sympathetic innervation via alpha 1 adrenoceptors on diabetes target organs and the interindividual variability of this receptor sensitivity, the existence of a subtype of type 2 diabetes with hyperactivation of alpha 1 adrenoceptors (HA1A) is proposed. Based on the literature review, the potential characteristics of this phenotype and its susceptibility to certain complications have been identified in this article.

Cardiac β-adrenergic responsiveness of obese Zucker rats: The role of AMPK

NEW FINDINGS

What is the central question of the study? Is the reduced signalling of AMP-activated protein kinase (AMPK), a key regulator of energy homeostasis in the heart, responsible for the reduced β-adrenergic responsiveness of the heart in obesity? What is the main finding and its importance? Inhibition of AMPK in isolated hearts prevented the reduced cardiac β-adrenergic responsiveness of obese rats, which was accompanied by reduced phosphorylation of AMPK, a proxy of AMPK activity. This suggests a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart, and it suggests that AMPK might be an important target to restore the β-adrenergic responsiveness in the heart in obesity.

ABSTRACT

The obesity epidemic impacts heavily on cardiovascular health, in part owing to changes in cardiac metabolism. AMP-activated protein kinase (AMPK) is a key regulator of energy homeostasis in the heart and is regulated by β-adrenoceptors (β-ARs) in normal conditions. In obesity, chronic sympathetic overactivation leads to impaired cardiac β-AR responsiveness, although it is unclear whether AMPK signalling, downstream of β-ARs, contributes to this dysfunction. Therefore, we aimed to determine whether reduced AMPK signalling is responsible for the reduced β-AR responsiveness in obesity. In isolated hearts of lean and obese Zucker rats, we tested β-AR responsiveness to the β₁ -AR agonist isoprenaline (ISO, 1 × 10^-10 to 5 × 10^-8  m) in the absence and presence of the AMPK inhibitor, compound C (CC, 10 μm). The β₁ -AR expression and AMPK phosphorylation were assessed by Western blot. β-Adrenergic responsiveness was reduced in the hearts of obese rats (logEC₅₀ of ISO-developed pressure dose-response curves: lean -8.53 ± 0.13 × 10^x  m versus obese -8.35 ± 0.10 × 10^x  m ; P < 0.05 lean versus obese, n = 6 per group). This difference was not apparent after AMPK inhibition (logEC₅₀ of ISO-developed pressure curves: lean CC -8.19 ± 0.12 × 10^x  m versus obese CC 8.17 ± 0.13 × 10^x  m, P < 0.05, n = 6 per group). β₁ -Adrenergic receptor expression and AMPK phosphorylation were reduced in hearts of obese rats (AMPK at Thr¹⁷² : lean 1.73 ± 0.17 a.u. versus lean CC 0.81 ± 0.13 a.u., and obese 1.18 ± 0.09 a.u. versus obese CC 0.81 ± 0.16 a.u., P < 0.05, n = 6 per group). Thus, a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart exists, and AMPK might be an important target to restore the reduced cardiac β-adrenergic responsiveness in obesity.

Disparities in Hypertension Among African-Americans: Implications of Insufficient Sleep

PURPOSE OF REVIEW

Sleep deficiency has been proposed as a potential contributor to racial disparities in cardiovascular health. We present contemporary evidence on the unequal burden of insufficient sleep in Blacks/African-Americans and the repercussions for disparate risk of hypertension.

RECENT FINDINGS

The prevalence of insufficient sleep is high and rising and has been recognized as an important cardiovascular risk factor. Presumably due to a constellation of environmental, psychosocial, and individual determinants, these risks appear exacerbated in Blacks/African-Americans, who are more likely to experience short sleep than other ethnic/racial groups. Population-based data suggest that the risk of hypertension associated with sleep deficiency is greater in those of African ancestry. However, there is a paucity of experimental evidence linking short sleep duration to blood pressure levels in African-Americans. Blacks/African-Americans may be more vulnerable to sleep deficiency and to its hypertensive effects. Future research is needed to unequivocally establish causality and determine the mechanism underlying the postulated racial inequalities in sleep adequacy and consequent cardiovascular risk.

Religiosity, Education, John Henryism Active Coping, and Cardiovascular Responses to Anger Recall for African American Men

The present study examined if high levels of religious attendance (ORG), private religious activity (NOR), or intrinsic religiosity (SUB) buffer cardiovascular responses to active speech and anger recall lab stressors alone and by John Henryism Active Coping (JHAC) and educational attainment. A sample of 74 healthy African American males, aged 23 to 47 years, completed psychosocial surveys and a lab reactivity protocol involving active speech and anger recall with a 5-minute baseline and ensuing recovery periods. Measures of religiosity, JHAC, and education were related to continuous measures of systolic and diastolic blood pressure (BP), for each task and rest period with repeated measures ANOVA tests. The period by education by JHAC interaction effect was significant for diastolic BP responses at low but not higher NOR. At low education and low NOR, diastolic BP levels increased significantly during anger recall and ensuing recovery for high but not low JHAC persons. Thus, being deprived of education and private religious activity may put these African American men in a vulnerable situation where higher effort coping may exacerbate their cardiovascular reactivity and recovery to anger induction.

The effect of beta-adrenergic blockade on inflammatory and cardiovascular responses to acute mental stress

Acute mental stress elicits increases in plasma cytokine concentrations in humans, but the underlying mechanisms remain poorly understood. We assessed the impact of beta-adrenergic blockade on plasma interleukin 6 (IL-6) and IL-1 receptor antagonist (IL-1Ra) responses in a parallel group, double-blind randomised placebo-controlled trial involving 64 healthy young adult volunteers. Participants were administered 80 mg slow-release propranolol or placebo daily for 7 days before the stress testing session in which responses to 3 behavioural challenges (public speaking, mirror tracing, mental arithmetic) were evaluated. Propranolol administration was associated with reduced baseline levels of heart rate and IL-1Ra, and systolic blood pressure (BP) in men. Tasks stimulated increased plasma IL-6 concentrations sampled 45 min and 75 min after challenge, but these responses were blocked by propranolol in men (p < 0.001). Propranolol did not influence IL-6 responses in women, or IL-1Ra in either sex. Blood pressure and heart rate increased markedly during the tasks, but there was no differential stress reactivity in propranolol and placebo conditions. The results of the study support a role of sympathetic nervous system activation in stimulating acute IL-6 responses to stress, but only in men. The reasons for the differences between men and women remain to be resolved.

Impact of Racial Discrimination and Hostility on Adrenergic Receptor Responsiveness in African American Adults

OBJECTIVE

Racial discrimination is increasingly recognized as a contributor to increased cardiovascular disease (CVD) risk among African Americans. Previous research has shown significant overlap between racial discrimination and hostility, an established predictor of CVD risk including alterations in adrenergic receptor functioning. The present study examined the associations of racial discrimination and hostility with adrenergic receptor responsiveness.

METHODS

In a sample (N = 57) of young to middle-aged African American adults (51% female) with normal and mildly elevated blood pressure, a standardized isoproterenol sensitivity test (CD25) was used to evaluate β-AR responsiveness, whereas the dose of phenylephrine required to increase mean arterial pressure by 25 mm Hg (PD25) was used to assess α1-AR responsiveness. Racial discrimination was measured using the Perceived Racism Scale and hostility was assessed using the Cook-Medley Hostility Scale.

RESULTS

In hierarchical regression models, greater racial discrimination, but not hostility, emerged as a significant predictor of decreased β-adrenergic receptor responsiveness (β = .38, p = .004). However, moderation analysis revealed that the association between racial discrimination and blunted β-adrenergic receptor responsiveness was strongest among those with higher hostility (β = .49, 95% confidence interval = .17-.82, p = .004). In addition, hostility, but not racial discrimination, significantly predicted α1-AR responsiveness.

CONCLUSIONS

These findings suggest racial discrimination was associated with blunted β-adrenergic receptor responsiveness, providing further evidence of the potential contribution of racial discrimination to increased CVD risk among African Americans. The adverse effects of discrimination on cardiovascular health may be enhanced in individuals with higher levels of hostility.

Blood pressure reactivity to psychological stress is associated with clinical outcomes in patients with heart failure

INTRODUCTION

Cardiovascular (CV) reactivity to psychological stress has been implicated in the development and exacerbation of cardiovascular disease (CVD). Although high CV reactivity traditionally is thought to convey greater risk of CVD, the relationship between reactivity and clinical outcomes is inconsistent and may depend on the patient population under investigation. The present study examined CV reactivity in patients with heart failure (HF) and its potential association with long-term clinical outcomes.

METHODS

One hundred ninety-nine outpatients diagnosed with HF, with ejection fraction ≤40%, underwent an evaluation of blood pressure (BP) and heart rate reactivity to a laboratory-based simulated public-speaking stressor. Cox proportional hazards regression models were used to examine the prospective association between BP and heart rate reactivity on a combined end point of death or CV hospitalization over a 5-year median follow-up period.

RESULTS

Both systolic blood pressure (SBP) and diastolic blood pressure (DBP) reactivity, quantified as continuous variables, were inversely related to risk of death or CV hospitalization (Ps < .01) after controlling for established risk factors, including HF disease severity and etiology. In similar models, heart rate reactivity was unrelated to outcome (P = .12). In models with tertiles of reactivity, high SBP reactivity, compared with intermediate SBP reactivity, was associated with lower risk (hazard ratio [HR] = .498, 95% CI .335-.742, P =.001), whereas low SBP reactivity did not differ from intermediate reactivity. For DBP, high reactivity was marginally associated with lower risk compared with intermediate DBP reactivity (HR = .767, 95% CI .515-1.14, P =.193), whereas low DBP reactivity was associated with greater risk (HR = 1.49, 95% CI 1.027-2.155, P =.0359). No relationship of heart rate reactivity to outcome was identified.

CONCLUSIONS

For HF patients with reduced ejection fraction, a robust increase in BP evoked by a laboratory-based psychological challenge was associated with lower risk for adverse CVD events and may be a novel and unique marker of left ventricular systolic reserve that is accompanied by a more favorable long-term prognosis.