Effects of antihypertensive treatment on endothelial function in postmenopausal hypertensive women. A significant role for aldosterone inhibition

Endothelial dysfunction in human essential hypertension

Although the endothelium has a number of important functions, the term endothelial dysfunction is commonly used to describe impairment in its vasodilatory capacity. It is increasingly recognized that this is related to hypertension, although whether it predates essential hypertension or is a consequence of it is still unknown. In this review, we explore the mechanisms of endothelial dysfunction in essential hypertension, its prognostic significance and methods of pharmacological reversal.

Endothelial function in postmenopausal women with nighttime systolic hypertension

OBJECTIVE

Hypertension becomes more prevalent in women during their postmenopausal years. Nighttime systolic blood pressure (SBP) is especially predictive of adverse cardiac events, and the relationship between rising nighttime SBP and cardiovascular risk increases more rapidly in women compared with men. The reasons for the prognostic significance of nighttime SBP are not completely known but may involve vascular endothelial dysfunction. The purposes of this study were to examine the relationship between nighttime SBP and endothelial function, as assessed by brachial artery flow-mediated dilation (FMD), and to determine whether postmenopausal women with nighttime hypertension (SBP ≥120 mm Hg) evidenced greater endothelial dysfunction compared with women with normal nighttime SBP.

METHODS

One hundred postmenopausal women (mean [SD] age, 65.8 [7.5] y; mean [SD] body mass index, 28.3 [4.7] kg/m; hypertension, 47%; coronary artery disease, 51%; mean [SD] clinic SBP, 137 [17] mm Hg; mean [SD] clinic diastolic blood pressure, 67 [11] mm Hg; nighttime hypertension, 34 women) underwent 24-hour ambulatory blood pressure monitoring, actigraphy, and brachial artery FMD assessment.

RESULTS

Multivariate regression models showed that higher nighttime SBP and larger baseline artery diameter were inversely related to FMD. Nighttime SBP and baseline artery diameter accounted for 23% of the variance in FMD. After adjustment for baseline artery diameter, women with nighttime hypertension had lower mean (SD) FMD than women with normal nighttime SBP (2.95% [0.65%] vs 5.52% [0.46%], P = 0.002).

CONCLUSIONS

Nighttime hypertension is associated with reduced endothelial function in postmenopausal women. Research examining the therapeutic benefits of nighttime hypertension treatment on endothelial function and future cardiovascular risk in postmenopausal women is warranted.

Mineralocorticoid receptors in vascular disease: connecting molecular pathways to clinical implications

The mineralocorticoid receptor (MR), a steroid-hormone-activated transcription factor, plays a substantial role in cardiovascular diseases. MR antagonists (MRAs) have long been appreciated as effective treatments for heart failure and hypertension; however, recent research suggests that additional patient populations may also benefit from MRA therapy. Experimental evidence demonstrates that in addition to its classic role in the regulating sodium handling in the kidney, functional MR is expressed in the blood vessels and contributes to hypertension, vascular inflammation and remodeling, and atherogenesis. MR activation drives pathological phenotypes in smooth muscle cells, endothelial cells, and inflammatory cells, whereas MRAs inhibit these effects. Collectively, these studies demonstrate a new role for extrarenal MR in cardiovascular disease. This review summarizes these new lines of evidence and how they contribute to the mechanisms of atherosclerosis, pulmonary and systemic hypertension, and vein graft failure, and describes new patient populations that may benefit from MRA therapy.

Hemodynamic and hormonal patterns of untreated essential hypertension in men and women

BACKGROUND

Knowledge of hemodynamic factors accounting for the development of hypertension should help to tailor therapeutic approaches and improve blood pressure control. Few data exist regarding sex differences of hemodynamic factors contributing to hypertension progression among patients with untreated nondiabetic stage I and II prehypertension (PreHyp) as defined by the Joint National Committee-7 guidelines (JNC-7).

METHODS

We utilized noninvasive impedance cardiography, applanation tonometry and plasma measures of angiotensin II, angiotensin (1-7), serum aldosterone, high-sensitivity C-reactive protein (hs-CRP) and cytokine biomarkers of inflammation to characterize the hemodynamic and hormonal profile of 100 patients with untreated hypertension (39 women).

RESULTS

Despite there being no differences between women and men in terms of office blood pressure, heart rate and body mass index, men demonstrated lower values of pulse pressure, systemic vascular resistance, brachial artery pulse wave velocity and augmentation index. In each of the three hypertension categories, the increased blood pressure in men was associated with significant augmentations in stroke volume and cardiac output compared with women. Sex-related hemodynamic differences were associated in women with higher plasma levels of leptin, hs-CRP, plasma angiotensin II and serum aldosterone, and no differences in the serum concentrations of cytokinins. In women but not men, hs-CRP correlated with plasma concentrations of transforming growth factor β1 (TGFβ1) and body weight; in addition, plasma TGFβ1 correlated with levels of serum vascular cell adhesion molecule 1.

CONCLUSION

The impact of sex differences in the hemodynamic factors accounting for the elevation in arterial pressure in subjects with essential hypertension has been poorly characterized or this information is not available. We suggest that this gap in knowledge may adversely influence choices of drug treatment since our study shows for the first time significant differences in the hemodynamic and hormonal mechanisms accounting for the increased blood pressure in women compared to men.

The cardioprotective effects of mineralocorticoid receptor antagonists

Despite state-of-the-art reperfusion therapy, morbidity and mortality remain significant in patients with an acute myocardial infarction. Therefore, novel strategies to limit myocardial ischemia-reperfusion injury are urgently needed. Mineralocorticoid receptor (MR) antagonists are attractive candidates for this purpose, since several clinical trials in patients with heart failure have reported a survival benefit with MR antagonist treatment. MRs are expressed by several cells of the cardiovascular system, including cardiomyocytes, cardiac fibroblasts, vascular smooth muscle cells, and endothelial cells. Experiments in animal models of myocardial infarction have demonstrated that acute administration of MR antagonists, either before ischemia or immediately at the moment of coronary reperfusion, limits infarct size. This action appears to be independent of the presence of aldosterone and cortisol, which are the endogenous ligands for the MR. The cardioprotective effect is mediated by a nongenomic intracellular signaling pathway, including adenosine receptor stimulation, and activation of several components of the Reperfusion Injury Salvage Kinase (RISK) pathway. In addition to limiting infarct size, MR antagonists can improve scar healing when administered shortly after reperfusion and can reduce cardiac remodeling post myocardial infarction. Clinical trials are currently being performed studying whether early administration of MR antagonists can indeed improve prognosis in patients with an acute myocardial infarction, independent of the presence of heart failure.

Resistin involved in endothelial dysfunction among preclinical Tibetan male young adults

INTRODUCTION

Resistin, an adipocyte-derived hormone, was found to be linked to metabolic syndrome and insulin resistance over the past decade. There is growing evidence that resistin plays a potential role in endothelial dysfunction. To the best of our knowledge, few studies have been concerned with the effect of resistin on endothelial function in a Tibetan population.

AIMS

To investigate the correlation of resistin and endothelial function among preclinical Tibetan male young adults.

MATERIALS AND METHODS

All participants recruited were young adults between 30 and 40 years old of male gender in Lhasa city. All subjects were native Tibetan. A total of 90 healthy subjects were accepted after excluding hypertension, diabetes, hyperlipidemia or coronary artery disease. The subjects were divided into three groups according to flow-mediated dilation (FMD): lower FMD (group A), intermediate FMD (group B) and higher FMD (group C). Body mass index, systolic blood pressure (SBP), diastolic blood pressure (DBP) and cigarette smoking were evaluated. Venous blood was sampled for the measurement of lipid profile, fasting blood glucose (FBG), fasting insulin (FINS), endothelin-1 (ET-1) and plasma resistin quantitation. The non-invasive vascular endothelial function was evaluated through the measurement of FMD with B-mode ultrasound. The insulin resistance was estimated as homeostatic model assessment of insulin resistance (HOMA-IR) = FINS(mu/L)*FBG(mmol/L)/22.5.

RESULTS

No statistical significance was found between groups in age, smoking, SBP, DBP, fasting insulin, total cholesterol and HOMA-IR (p>0.05). In the lipid profile, high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol in group C were better than in groups A and B (p<0.01). Body mass index, which is an indicator for obesity, was much lower in group C than in group A and B (p<0.05 and 0.01 respectively). Comparison of plasma resistin concentrations: group A > group B > group C (p<0.01). Comparison of plasma ET-1 concentrations had a similar result: group A > group B > group C (p<0.05). The multivariate regression analysis showed that total cholesterol (p<0.05), LDL cholesterol (p<0.01), plasma resistin (p<0.01) and plasma ET-1 (p<0.01) were correlated with FMD.

CONCLUSIONS

Resistin is involved in endothelial dysfunction in preclinical male young Tibetan adults.