Cardiovascular alteration and treatment of hypertension: do men and women differ?

The Pathophysiology, Prognosis and Treatment of Hypertension in Females from Pregnancy to Post-menopause: A Review

PURPOSE OF REVIEW

We summarise the physiological changes and risk factors for hypertension in females, potential sex-specific management approaches, and long-term prognosis.

KEY FINDINGS

Pregnancy and menopause are two key phases of the life cycle where females undergo significant biological and physical changes, making them more prone to developing hypertension. Gestational hypertension occurs from changes in maternal cardiac output, kidney function, metabolism, or placental vasculature, with one in ten experiencing pregnancy complications such as intrauterine growth restriction and delivery complications such as premature birth. Post-menopausal hypertension occurs as the protective effects of oestrogen are reduced and the sympathetic nervous system becomes over-activated with ageing. Increasing evidence suggests that post-menopausal females with high blood pressure (BP) experience greater risk of cardiovascular events at lower BP thresholds, and greater vulnerability to treatment-related adverse effects. Hypertension is a key risk factor for cardiovascular disease in females. Current BP treatment guidelines and recommendations are similar for both sexes, without addressing sex-specific factors. Future investigations into ideal diagnostic thresholds, BP control targets and treatment regimens in females are needed.

Measurements of Abdominal Obesity are Associated with Metabolic Syndrome Severity Independent of Hypertensive Phenotype in White but not Black Young Adults

PURPOSE

This study sought to determine if metabolic syndrome severity (MetSindex) was differentially associated with abdominal obesity based on waist circumference (WC) site and the presentation of hypertensive phenotypes in a group of young White and Black adults.

METHODS

A total of 139 young adult (22.5 ± 3.3 years) non-Hispanic White (n = 73) and non-Hispanic Black (n = 66) males and females (M 53, 86 F) completed this cross-sectional evaluation. Participants had their WC measured at three distinct locations along the abdomen which were used to calculate waist-to-hip and waist-to-height ratios. Systolic (SBP) and diastolic blood pressure (DBP) were collected and used to calculate mean arterial pressure (MAP). In addition to traditional metabolic syndrome (MetS) risk factors, BP values were individually used to produce three separate MetSindex scores representing three specific hypertensive phenotypes (MetSSBP, MetSDBP, MetSMAP), and each of these were evaluated against each abdominal obesity estimate.

RESULTS

MetSDBP and MetSSBP were significantly higher than all other indices for females (all p ≤ 0.002) and males (all p < 0.001), respectively. MetSDBP was significantly higher than MetSMAP for White females (p = 0.039), and MetSSBP was significantly higher than MetSDBP and MetSMAP (both p < 0.001) for Black males. Standalone and joint estimates of abdominal obesity were uniquely associated with MetSindex across hypertensive phenotypes for White, but not Black males and females.

CONCLUSIONS

Specific hypertensive phenotypes may differentially determine MetSindex, but these estimates are not associated with abdominal obesity in young Black adults regardless of measurement location. Healthcare professionals should address this disparity by providing more comprehensive MetS screening procedures for young Black adults.

CLINICAL TRIALS REGISTRATION

NCT05885672.

Hypertension in Women and Pregnancy

Hypertension has been shown to have long-term cardiovascular effects if left untreated. Hypertension also has been shown to affect women during pregnancy, which can be detrimental not only to the patient but also to the fetus. Early identification and treatment are paramount to prevent adverse outcomes. This article details the epidemiology, clinical presentation, diagnosis, and treatment of essential hypertension in women, gestational hypertension, preeclampsia, and eclampsia.

Hypertension in Women

Hypertension is one of the main causes of morbidity and mortality in the human population. Nevertheless, the intricate network of pathophysiological mechanisms that lead to the development of hypertension in women still awaits to be fully understood. From young age to maturity and senescence, the female body transits through different stages, each of them characterized with specific physiological features and disposition to particular pathological conditions, and that is exactly what makes the understanding of the genesis and adequate treatment of hypertension in women so challenging. Clinical and experimental findings emphasize the role of sex hormones, autonomic nervous system, renin-angiotensin-aldosterone system and arterial stiffness in the development of chronically elevated blood pressure in females. The purpose of this review is to briefly summarize the knowledge of the mechanisms and treatment of hypertension in women.

The Impact of Estrogen Receptor in Arterial and Lymphatic Vascular Diseases

The lower incidence of cardiovascular diseases in pre-menopausal women compared to men is well-known documented. This protection has been largely attributed to the protective effect of estrogens, which exert many beneficial effects against arterial diseases, including vasodilatation, acceleration of healing in response to arterial injury, arterial collateral growth and atheroprotection. More recently, with the visualization of the lymphatic vessels, the impact of estrogens on lymphedema and lymphatic diseases started to be elucidated. These estrogenic effects are mediated not only by the classic nuclear/genomic actions via the specific estrogen receptor (ER) α and β, but also by rapid extra-nuclear membrane-initiated steroid signaling (MISS). The ERs are expressed by endothelial, lymphatic and smooth muscle cells in the different vessels. In this review, we will summarize the complex vascular effects of estrogens and selective estrogen receptor modulators (SERMs) that have been described using different transgenic mouse models with selective loss of ERα function and numerous animal models of vascular and lymphatic diseases.

Cardiac-specific overexpression of metallothionein attenuates L-NAME-induced myocardial contractile anomalies and apoptosis

Hypertension contributes to the high cardiac morbidity and mortality. Although oxidative stress plays an essential role in hypertensive heart diseases, the mechanism remains elusive. Transgenic mice with cardiac overexpression of metallothionein, a heavy metal‐binding scavenger, were challenged with N^G‐nitro‐L‐arginine methyl ester (L‐NAME) for 14 days prior to measurement of myocardial contractile and intracellular Ca²⁺ anomalies as well as cell signalling mechanisms using Western blot and immunofluorescence analysis. L‐NAME challenge elicited hypertension, macrophage infiltration, oxidative stress, inflammation and cardiac dysfunction manifested as increased proinflammatory macrophage marker F4/80, interleukin‐1β (IL‐1β), intracellular O2- production, LV end systolic and diastolic diameters as well as depressed fractional shortening. L‐NAME treatment reduced mitochondrial membrane potential (MMP), impaired cardiomyocyte contractile and intracellular Ca²⁺ properties as evidenced by suppressed peak shortening, maximal velocity of shortening/relengthening, rise in intracellular Ca²⁺, along with elevated baseline and peak intracellular Ca²⁺. These unfavourable mechanical changes and decreased MMP (except blood pressure and macrophage infiltration) were alleviated by overexpression of metallothionein. Furthermore, the apoptosis markers including BAD, Bax, Caspase 9, Caspase 12 and cleaved Caspase 3 were up‐regulated while the anti‐apoptotic marker Bcl‐2 was decreased by L‐NAME treatment. Metallothionein transgene reversed L‐NAME‐induced changes in Bax, Bcl‐2, BAD phosphorylation, Caspase 9, Caspase 12 and cleaved Caspase 3. Our results suggest that metallothionein protects against L‐NAME‐induced myocardial contractile anomalies in part through inhibition of apoptosis.

Resistance or aerobic training decreases blood pressure and improves cardiovascular autonomic control and oxidative stress in hypertensive menopausal rats

We investigated whether resistance training (RT) vs. aerobic training (AT) differentially impacts on arterial pressure and related mechanisms in ovariectomized spontaneously hypertensive rats (SHRs). Female SHRs were ovariectomized and assigned to one of the following groups: sedentary, AT, or RT; sham sedentary SHR were used as control group. AT was performed on a treadmill, whereas RT was performed on a vertical ladder. Both exercise protocols were performed for 8 wk, 5 days/wk. Arterial pressure, baroreflex sensitivity, autonomic modulation, and cardiac oxidative stress parameters (lipid peroxidation, protein oxidation, redox balance, NADPH oxidase, and antioxidant enzymes activities) were analyzed. Ovariectomy increased mean arterial pressure (∼9 mmHg), sympathetic modulation (∼40%), and oxidative stress in sedentary rats. Both RT and AT reduced mean arterial pressure (∼20 and ∼8 mmHg, respectively) and improved baroreflex sensitivity compared with sedentary ovariectomized rats. However, RT-induced arterial pressure decrease was significantly less pronounced than AT. Lipid peroxidation and protein oxidation were decreased while antioxidant enzymes were increased in both trained groups vs. sedentaries. The reduced gluthatione was higher after AT vs. other groups, whereas oxidized gluthatione was lower after RT vs. AT. Moreover, sympathetic and parasympathetic modulations were highly correlated with cardiac oxidative stress parameters. In conclusion, both RT and AT can decrease arterial pressure in a model of hypertension and menopause; although, at different magnitudes this decrease was related to attenuated autonomic dysfunction in association with cardiac oxidative stress improvement in both exercise protocols.

Association Between Hypertension, Menopause, and Cognition in Women

The aim of this study was to investigate the cognitive state in women and its relation to menopause and hypertension (HTN). The authors included 1034 women aged 47.13±15.71 years. The prevalence of HTN was 47.1%, with 67.8% of patients treated and 48.6% controlled. Cognitive impairment was higher among hypertensive menopausal (mini-Boston Naming Test: 7.4±3.1 vs 8.5±2.4, P<.001; Clock-Drawing Test: 5.2±2 vs 5.6±1.6, P<.01). Using logistic regression adjusted by age and education level, statistical differences were found in the results from the mini-Boston Naming Test between menopausal hypertensive vs menopausal normotensive women (odds ratio, 1.48; 95% confidence interval, 1.06-2.07; P=.021), and no difference between nonmenopausal hypertensive vs menopausal normotensive women (odds ratio, 0.89; 95% confidence interval, 0.51-1.57; P=.697). The P interaction between both groups was significant (P=.038). The possibility of alteration in cortical functions in menopausal hypertensive woman showed a relative increment of 48% (P=.021). The association between HTN and menopause increases the possibility of compromising the semantic memory by 50%.

Remodeling of hyperpolarization-activated current, Ih, in Ah-type visceral ganglion neurons following ovariectomy in adult rats

Hyperpolarization-activated currents (I_h) mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels modulate excitability of myelinated A− and Ah-type visceral ganglion neurons (VGN). Whether alterations in I_h underlie the previously reported reduction of excitability of myelinated Ah-type VGNs following ovariectomy (OVX) has remained unclear. Here we used the intact nodose ganglion preparation in conjunction with electrophysiological approaches to examine the role of I_h remodeling in altering Ah-type neuron excitability following ovariectomy in adult rats. Ah-type neurons were identified based on their afferent conduction velocity. Ah-type neurons in nodose ganglia from non-OVX rats exhibited a voltage ‘sag’ as well as ‘rebound’ action potentials immediately following hyperpolarizing current injections, which both were suppressed by the I_h blocker ZD7288. Repetitive spike activity induced afterhyperpolarizations lasting several hundreds of milliseconds (termed post-excitatory membrane hyperpolarizations, PEMHs), which were significantly reduced by ZD7288, suggesting that they resulted from transient deactivation of I_h during the preceding spike trains. Ovariectomy reduced whole-cell I_h density, caused a hyperpolarizing shift of the voltage-dependence of I_h activation, and slowed I_h activation. OVX-induced I_h remodeling was accompanied by a flattening of the stimulus frequency/response curve and loss of PEMHs. Also, HCN1 mRNA levels were reduced by ∼30% in nodose ganglia from OVX rats compared with their non-OVX counterparts. Acute exposure of nodose ganglia to 17beta-estradiol partly restored I_h density and accelerated I_h activation in Ah-type cells. In conclusion, I_h plays a significant role in modulating the excitability of myelinated Ah-type VGNs in adult female rats.

Sex-specific differences in natriuretic peptide and nitric oxide synthase expression in ANP gene-disrupted mice

Sex-specific differences in hormone-mediated gene regulation may influence susceptibility to cardiac hypertrophy, a primary risk factor for cardiovascular disease. Under hormonal influence, natriuretic peptide (NP) and nitric oxide synthase (NOS) systems modulate cardio-protective gene programs through common downstream production of cyclic guanosine 3'-5' monophosphate (cGMP). Ablation of either system can adversely affect cardiac adaptation to stresses and insults. This study elucidates sex-specific differences in cardiac NP and NOS system gene expression and assesses the impact of the estrous cycle on these systems using the atrial natriuretic peptide gene-disrupted (ANP(-/-)) mouse model. Left ventricular expression of the NP and NOS systems was analyzed using real-time quantitative polymerase chain reaction in 13- to 16-week-old male, proestrous and estrous female ANP(+/+) and ANP(-/-) mice. Left ventricular and plasma cGMP levels were measured to assess the convergent downstream effects of the NP and NOS systems. Regardless of genotype, males had higher expression of the NP system while females had higher expression of the NOS system. In females, transition from proestrus to estrus lowered NOS system expression in ANP(+/+) mice while the opposite was observed in ANP(-/-) mice. No significant changes in left ventricular cGMP levels across gender and genotype were observed. Significantly lower plasma cGMP levels were observed in ANP(-/-) mice compared to ANP(+/+) mice. Regardless of genotype, sex-specific differences in cardiac NP and NOS system expression exist, each sex enlisting a predominant system to conserve downstream cGMP. Estrous cycle-mediated alterations in NOS system expression suggests additional hormone-mediated gene regulation in females.

The influence of gender and sexual hormones on incidence and outcome of chronic kidney disease

It has long been known that the female sex is associated with a better clinical outcome in chronic renal diseases. Although many experimental, clinical, and epidemiological studies in adults have attempted to explain the difference in disease progression between females and males, a definitive understanding of the underlying mechanisms is still lacking. Hormone-modulating therapies are being increasingly used for various indications (such as post-menopausal hormone replacement, estrogen- or androgen-receptor antagonists for cancer therapy). Therefore, a deeper knowledge of the interaction between sexual hormones and progression of kidney disease is important, as hormone-modulating therapy for non-renal indication may influence both kidney structure and function. In addition, specific modulation of the sexual hormone system, such as the use of selective estrogen receptor modulators, may represent a therapeutic option for patients with renal diseases. Although conclusive data on this topic in the pediatric population are still lacking, the aim of this review is to familiarize pediatric nephrologists with gender-specific differences in renal physiology, pathophysiology, and the progression of kidney diseases. Experimental models that analyze the effects of sexual hormones on renal structure and function are discussed. It is hoped that this review will stimulate researchers to focus on pediatric studies that will provide a deeper insight into the interaction of gender hormones and the kidney both before and during puberty.

Association between prenatal lead exposure and blood pressure in children

BACKGROUND

Lead exposure in adults is associated with hypertension. Altered prenatal nutrition is associated with subsequent risks of adult hypertension, but little is known about whether prenatal exposure to toxicants, such as lead, may also confer such risks.

OBJECTIVES

We investigated the relationship of prenatal lead exposure and blood pressure (BP) in 7- to 15-year-old boys and girls.

METHODS

We evaluated 457 mother-child pairs, originally recruited for an environmental birth cohort study between 1994 and 2003 in Mexico City, at a follow-up visit in 2008-2010. Prenatal lead exposure was assessed by measurement of maternal tibia and patella lead using in vivo K-shell X-ray fluorescence and cord blood lead using atomic absorption spectrometry. BP was measured by mercury sphygmomanometer with appropriate-size cuffs.

RESULTS

Adjusting for relevant covariates, maternal tibia lead was significantly associated with increases in systolic BP (SBP) and diastolic BP (DBP) in girls but not in boys (p-interaction with sex = 0.025 and 0.007 for SBP and DBP, respectively). Among girls, an interquartile range increase in tibia lead (13 μg/g) was associated with 2.11-mmHg [95% confidence interval (CI): 0.69, 3.52] and 1.60-mmHg (95% CI: 0.28, 2.91) increases in SBP and DBP, respectively. Neither patella nor cord lead was associated with child BP.

CONCLUSIONS

Maternal tibia lead, which reflects cumulative environmental lead exposure and a source of exposure to the fetus, is a predisposing factor to higher BP in girls but not boys. Sex-specific adaptive responses to lead toxicity during early-life development may explain these differences.

Evidence for sex differences in cardiovascular aging and adaptive responses to physical activity

There are considerable data addressing sex-related differences in cardiovascular system aging and disease risk/progression. Sex differences in cardiovascular aging are evident during resting conditions, exercise, and other acute physiological challenges (e.g., orthostasis). In conjunction with these sex-related differences-or perhaps even as an underlying cause-the impact of cardiorespiratory fitness and/or physical activity on the aging cardiovascular system also appears to be sex-specific. Potential mechanisms contributing to sex-related differences in cardiovascular aging and adaptability include changes in sex hormones with age as well as sex differences in baseline fitness and the dose of activity needed to elicit cardiovascular adaptations. The purpose of the present paper is thus to review the primary research regarding sex-specific plasticity of the cardiovascular system to fitness and physical activity in older adults. Specifically, the paper will (1) briefly review known sex differences in cardiovascular aging, (2) detail emerging evidence regarding observed cardiovascular outcomes in investigations of exercise and physical activity in older men versus women, (3) explore mechanisms underlying the differing adaptations to exercise and habitual activity in men versus women, and (4) discuss implications of these findings with respect to chronic disease risk and exercise prescription.

Differences in cardiovascular disease risk factor management in primary care by sex of physician and patient

PURPOSE

The purpose of this study was to evaluate differences in the management of cardiovascular disease (CVD) risk factors based upon the sex of the patient and physician and their interaction in primary care practice.

METHODS

We evaluated CVD risk factor management in 4,195 patients cared for by 39 male and 16 female primary care physicians in 30 practices in southeastern New England.

RESULTS

Many of the sex-based differences in CVD risk factor management on crude analysis are lost once adjusted for confounding factors found at the level of the patient, physician, and practice. In multilevel adjusted analyses, styles of CVD risk factor management differed by the sex of the physician, with more female physicians documenting diet and weight loss counseling for hypertension (odds ratio [OR] = 2.22; 95% confidence interval [CI], 1.12-4.40) and obesity (OR = 2.14; 95% CI, 1.30-3.51) and more physical activity counseling for obesity (OR = 2.03; 95% CI, 1.30-3.18) and diabetes (OR = 6.55; 95% CI, 2.01-21.33). Diabetes management differed by the sex of the patient, with fewer women receiving glucose-lowering medications (OR = 0.49; 95% CI, 0.25-0.94), angiotensin-converting enzyme inhibitor therapy (OR = 0.39; 95% CI, 0.22-0.72), and aspirin prophylaxis (OR = 0.30; 95% CI, 0.15-0.58).

CONCLUSION

Quality of care as measured by patients meeting CVD risk factors treatment goals was similar regardless of the sex of the patient or physician. Selected differences were found in the style of CVD risk factor management by sex of physician and patient.

Efficacy and safety of fixed combinations of irbesartan/hydrochlorothiazide in hypertensive women: the inclusive trial

OBJECTIVE

This post hoc analysis of the Irbesartan/Hydrochlorothiazide Blood Pressure Reductions in Diverse Patient Populations (INCLUSIVE) trial evaluated the efficacy and safety of irbesartan/hydrochlorothiazide (HCTZ) in a diverse population of hypertensive women.

METHODS

INCLUSIVE was a multicenter, prospective, open-label, single-arm trial. Adult subjects had uncontrolled systolic blood pressure (SBP 140-159 mm Hg; 130-159 mm Hg for those with type 2 diabetes mellitus [T2DM]) after > or =4 weeks of antihypertensive monotherapy. Treatment was sequential: placebo (4-5 weeks), HCTZ 12.5 mg (2 weeks), irbesartan/HCTZ 150/12.5 mg (8 weeks), and irbesartan/HCTZ 300/25 mg (8 weeks). Mean changes from baseline to treatment end in SBP and diastolic blood pressure (DBP), BP goal attainment, and safety were assessed.

RESULTS

Treatment with irbesartan/HCTZ was associated with significant mean reductions in BP (intent-to-treat population, n = 370; SBP/DBP: -22.9/-10.3 +/- 14.7/8.8 mm Hg). Improvements in SBP were observed in all subgroups (p < 0.001): Caucasian (n = 207) -23.5 +/- 13.5 mm Hg; African American (n = 93) -21.0 +/- 17.2 mm Hg; Hispanics/Latino (n = 66) -23.6 +/- 14.3 mm Hg; age <65 years (n = 281) -22.5 +/- 14.7 mm Hg; age > or =65 years (n = 89) -24.3 +/- 14.5 mm Hg; T2DM (n = 97) -19.0 +/- 15.1 mm Hg; and metabolic syndrome (n = 187) -22.1 +/- 14.6 mm Hg. Overall, 82% (95% confidence interval [CI] 78%-86%) of women achieved their SBP goal, 86% (95% CI 83%-90%) achieved their DBP goal, and 76% (95% CI 71%-80%) achieved their dual SBP/DBP goal. Treatments were well tolerated in all groups.

CONCLUSIONS

Irbesartan/HCTZ treatment was effective and well tolerated in a diverse population of women whose BP was previously uncontrolled on monotherapy.

Electrophysiological and neuroanatomical evidence of sexual dimorphism in aortic baroreceptor and vagal afferents in rat

Evidence for sexual dimorphism in autonomic control of cardiovascular function is both compelling and confounding. Across healthy and disease populations sex-associated differences in neurocirculatory hemodynamics are far too complex to be entirely related to sex hormones. As an initial step toward identifying additional physiological mechanisms, we investigated whether there is a sex bias in the relative expression of low-threshold-myelinated and high-threshold-unmyelinated aortic baroreceptor afferents in rats. These two types of afferent fibers have markedly different reflexogenic effects upon heart rate and blood pressure and thus the potential impact upon baroreflex dynamics could be substantial. Our results, using a combination of a patch-clamp study of fluorescently identified aortic baroreceptor neurons (ABN) and morphometric analysis of aortic baroreceptor nerve fibers, demonstrate that females exhibit a greater percentage of myelinated baroreceptor fibers (24.8% vs. 18.7% of total baroreceptor fiber population, P < 0.01) and express a functional subtype of myelinated ABN rarely found in age-matched males (11% vs. 2.3%, n = 107, P < 0.01). Interestingly, this neuronal phenotype is more prevalent in the general population of female vagal afferent neurons (17.7% vs. 3.8%, n = 169, P < 0.01), and ovariectomy does not alter its expression but does lessen neuronal excitability. These data suggest there are fundamental neuroanatomical and electrophysiological differences between aortic baroreceptor afferents of female and male rats. Possible explanations are presented as to how such a greater prevalence of low-threshold myelinated afferents could be a contributing factor to the altered baroreflex sensitivity and vagal tone of females compared with males.

Sex-specific differences in chromosome-dependent regulation of vascular reactivity in female consomic rat strains from a SSxBN cross

High-throughput studies in the Medical College of Wisconsin Program for Genomic Applications (Physgen) were designed to link chromosomes with physiological function in consomic strains derived from a cross between Dahl salt-sensitive SS/JrHsdMcwi (SS) and Brown Norway normotensive BN/NHsdMcwi (BN) rats. The specific goal of the vascular protocol was to characterize the responses of aortic rings from these strains to vasoconstrictor and vasodilator stimuli (phenylephrine, acetylcholine, sodium nitroprusside, and bath hypoxia) to identify chromosomes that either increase or decrease vascular reactivity to these vasoactive stimuli. Because previous studies demonstrated sex-specific quantitative trait loci (QTLs) related to regulation of cardiovascular phenotypes in an F2 cross between the parental strains, males and females of each consomic strain were included in all experiments. As there were significant sex-specific differences in aortic sensitivity to vasoconstrictor and vasodilator stimuli compared with the parental SS strain, we report the results of the females separately from the males. There were also sex-specific differences in aortic ring sensitivity to these vasoactive stimuli in consomic strains that were fed a high-salt diet (4% NaCl) for 3 wk to evaluate salt-induced changes in vascular reactivity. Differences in genetic architecture could contribute to sex-specific differences in the development and expression of cardiovascular diseases via differential regulation and expression of genes. Our findings are the first to link physiological traits with specific chromosomes in female SS rats and support the idea that sex is an important environmental variable that plays a role in the expression and regulation of genes.

Sex-differences in circadian blood pressure variations in response to chronic angiotensin II infusion in rats

1. The aim of this study was to investigate the effect of chronic angiotensin II (AngII) infusion on the circadian rhythms of arterial blood pressure, heart rate (HR) and locomotor activity (ACT) in male and female rats. 2. Radiotelemetry probes were implanted into the aorta in male and female rats and allowed 10 days for recovery. Control levels for mean arterial pressure (MAP), HR and ACT were recorded for 3 days, then AngII (400 ng/kg per min s.c. via osmotic minipump) or vehicle (saline) was infused for 10 days (n = 6 per group). Further recordings of MAP, HR and ACT were made during days 8, 9 and 10 of the infusion period. 3. In response to AngII infusion, night and day-time MAP increased significantly in female (18 +/- 2 mmHg; 28 +/- 7 mmHg) and male (27 +/- 4 mmHg; 30 +/- 3 mmHg) rats, respectively. The degree of elevation in MAP in response to AngII was attenuated in the females during the night period (P(sex) < 0.05) but not the day (P(sex) = 0.2). Control night-day differences in MAP, HR and ACT averaged 7 +/- 1 mmHg, 58 +/- 5 b.p.m. and 30 +/- 4 units in the female and 6 +/- 1 mmHg, 43 +/- 3 b.p.m. (P(sex) < 0.05) and 14 +/- 2 units (P(sex) < 0.05) in male rats, respectively. AngII infusion disrupted MAP circadian rhythm in female (-4 +/- 2 mmHg) and male rats (1 +/- 2 mmHg; P(treat) < 0.01), but did not affect heart rate or locomotor activity. 4. In conclusion, sex differences in the circadian rhythm of heart rate and locomotor activity, but not arterial pressure exist under basal conditions. Circulating AngII modulated the circadian rhythm of MAP in female and male rats but not heart rate or locomotor activity. These findings have important implications for our understanding of circadian blood pressure rhythms in states of activation of the renin angiotensin system.

Sexual dimorphism in non-Mendelian inheritance

There is accumulating evidence for nongenetic transgenerational inheritance with conspicuous marked sexual dimorphism for both the modes of transmission and the effects. Given the critical spatiotemporal windows, the role of the sex chromosomes, the regulatory pathways underlying sexual differentiation during gonad and brain development, and other developmental processes, as well as the lifelong impact of sex hormones, it is not surprising that most of the common diseases, which often take root in early development, display some degree of sex bias. The flexibility of epigenetic marks may make it possible for environmental and nutritional factors, or endocrine disruptors to alter-during a particular spatiotemporal window in a sex-specific manner-the sex-specific methylation or demethylation of specific CpGs and histone/chromatin modifications underlying sex-specific expression of a substantial proportion of genes. Thus, finely tuned developmental program aspects, specific to one sex, may be more sensitive to specific environmental challenges, particularly during developmental programming and gametogenesis, but also throughout the individual's life under the influence of sex steroid hormones. This review highlights the importance of studying both sexes in epidemiologic protocols or dietary interventions both in humans and in experimental models in animals.

Predictors of blood pressure response to angiotensin receptor blocker/diuretic combination therapy: a secondary analysis of the irbesartan/hydrochlorothiazide blood pressure reductions in diverse patient populations (INCLUSIVE) study

The secondary analysis of the Irbesartan/Hydrochlorothiazide Blood Pressure Reductions in Diverse Patient Populations (INCLUSIVE) clinical trial investigated whether baseline demographic and clinical variables are predictive of different degrees of blood pressure reduction following an angiotensin II receptor blocker/diuretic treatment regimen. Irbesartan/hydrochlorothiazide and other angiotensin receptor blocker combinations with a diuretic have been shown to be effective in reducing systolic blood pressure in a diverse patient population previously uncontrolled on monotherapy. Ordinary least squares regression analysis was performed on the intent-to-treat population of the INCLUSIVE study to identify variables predictive of variations in blood pressure changes in response to irbesartan/hydrochlorothiazide combination therapy. Higher baseline systolic blood pressure, female sex, type 2 diabetes, and statin therapy were found to be predictive of additional blood pressure lowering with this combination. The impact of higher baseline systolic blood pressure and diabetic state on changes in systolic blood pressure were diminished in female patients compared with male patients. In conclusion, a significant correlation may exist between certain clinical/demographic characteristics and the extent of the therapeutic response with irbesartan/hydrochlorothiazide treatment.

INFLUENCE OF GENDER ON OXIDATIVE STRESS, LIPID PEROXIDATION, PROTEIN DAMAGE AND APOPTOSIS IN HEARTS AND BRAINS FROM SPONTANEOUSLY HYPERTENSIVE RATS

1. Hypertension leads to oxidative stress, lipid and protein damage, apoptosis and impaired cardiac contractile function. However, impact of gender on these hypertension-associated abnormalities has not been elucidated. 2. The present study evaluated the oxidative stress, lipid/protein damage, apoptosis in heart and brain tissues as well as cardiomyocyte contractile function in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) of both genders. Oxidative stress, lipid peroxidation, protein damage and apoptosis were assessed by glutathione (GSH) : reduced glutathione (GSSG) ratio, malondialdehyde (MDA) levels, protein carbonyl levels and caspase-3 activity, respectively. Cardiomyocyte contractile function was examined including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/-dL/dt). The SHR cardiomyocytes displayed reduced PS and +/-dL/dt compared with gender-matched WKY counterparts. Male but not female SHR cardiomyocytes possessed longer resting cell length, normal TPS and prolonged TR90. All mechanical parameters were comparable between male and female WKY rats with the exception of a higher TR90 in females. Hypertension did not significantly affect the GSH : GSSG ratio in the heart and brain tissues of either gender. Brain from female WKY rats displayed a reduced GSH : GSSG ratio. The MDA levels were unchanged and elevated, respectively, in SHR heart and SHR brain tissues from both genders. Protein carbonyl formation and caspase-3 activity were elevated in male but not female SHR hearts. Nonetheless, brain protein carbonyl level and caspase-3 activity were unaffected by hypertension or gender. 3. In summary, these results suggest that gender affects hypertension-associated oxidative stress, lipid and protein damage, apoptosis in heart and brain tissues and cardiomyocyte contractile function.