Body mass index predicts plasma aldosterone concentrations in overweight-obese primary hypertensive patients

Abnormal aldosterone physiology and cardiometabolic risk factors

Abnormal aldosterone physiology has been implicated in the pathogenesis of cardiometabolic diseases. Single aldosterone measurements capture only a limited range of aldosterone physiology. New methods of characterizing aldosterone physiology may provide a more comprehensive understanding of its relationship with cardiometabolic disease. We evaluated whether novel indices of aldosterone responses to dietary sodium modulation, the sodium-modulated aldosterone suppression-stimulation index (SASSI for serum and SAUSSI for urine), could predict cardiometabolic risk factors. We performed cross-sectional analyses on 539 subjects studied on liberal and restricted sodium diets with serum and urinary aldosterone measurements. SASSI and SAUSSI were calculated as the ratio of aldosterone on liberal (maximally suppressed aldosterone) to the aldosterone on restricted (stimulated aldosterone) diets and associated with risk factors using adjusted regression models. Cardiometabolic risk factors associated with either impaired suppression of aldosterone on liberal diet, or impaired stimulation on restricted diet, or both; in all of these individual cases, these risk factors associated with higher SASSI or SAUSSI. In the context of abnormalities that constitute the metabolic syndrome, there was a strong positive association between the number of metabolic syndrome components (0-4) and both SASSI and SAUSSI (P<0.0001) that was independent of known aldosterone secretagogues (angiotensin II, corticotropin, potassium). SASSI and SAUSSI exhibited a high sensitivity in detecting normal individuals with zero metabolic syndrome components (86% for SASSI and 83% for SAUSSI). Assessing the physiological range of aldosterone responses may provide greater insights into adrenal pathophysiology. Dysregulated aldosterone physiology may contribute to, or result from, early cardiometabolic abnormalities.

Increased total Renin levels but not Angiotensin-converting enzyme activity in obese patients with polycystic ovary syndrome

OBJECTIVE

To investigate the renin-angiotensin-aldosterone system and angiotensin-converting enzyme (ACE) activity in patients with polycystic ovarian syndrome (PCOS).

SUBJECTS AND METHODS

In this case-control study, 41 obese (PCOS) women and 29 healthy controls, matched for age and body mass index, were enrolled. Anthropometric, metabolic, and hormonal patterns, including plasma aldosterone, plasma renin, and ACE activity, were measured in each subject.

RESULTS

Plasma renin levels were significantly higher in PCOS patients (19.7 ± 14.5 µg/ml) compared with controls (12.9 ± 9.0 µg/ml, p < 0.05). ACE activity and aldosterone levels did not significantly differ between both groups (p = 0.15 and p = 0.18, respectively). Analysis of PCOS patients showed a significant correlation of fasting insulin levels with levels of renin (r = 0.305, p < 0.01) and free testosterone (r = 0.384, p = 0.001). Similarly, homeostasis model assessment index was positively correlated with total renin concentrations (r = 0.366, p < 0.01) and free testosterone (r = 0.352, p < 0.01).

CONCLUSION

Obese PCOS women had higher total renin levels, but not ACE activity and aldosterone levels, related to insulin resistance compared with controls.

Vascular actions of aldosterone

Aldosterone exerts direct effects on the vascular system by inducing oxidative stress, inflammation, hypertrophic remodeling, fibrosis, and endothelial dysfunction. Aldosterone exerts its effects through genomic and nongenomic pathways in a mineralocorticoid receptor (MR)-dependent or independent manner. Other aldosterone receptors such as GPR30 have been identified. A tight relation exists between the aldosterone and angiotensin II pathways, as well as with the endothelin-1 system. There is a correlation between plasma levels of aldosterone and cardiovascular risk. Recently, an increasing body of evidence has underlined the importance of aldosterone in cardiovascular complications associated with the metabolic syndrome, such as arterial remodeling and endothelial dysfunction. Blockade of MR is an increasingly used evidence-based therapy for many forms of cardiovascular disease, including hypertension, heart failure, chronic kidney disease, and diabetes mellitus.

Efficacy of amlodipine/olmesartan medoxomil ± HCTZ in obese patients uncontrolled on antihypertensive monotherapy

OBJECTIVE

BP-CRUSH (Blood Pressure Control in All Subgroups With Hypertension) was a phase IV, prospective, open-label, multicenter, single-arm, dose-titration study (N = 999). The present subgroup analysis reports the efficacy/safety of up to 20 weeks of treatment with amlodipine (AML)/olmesartan medoxomil (OM) ± hydrochlorothiazide (HCTZ) in obese and non-obese patients with hypertension uncontrolled on antihypertensive monotherapy.

RESEARCH DESIGN AND METHODS

Eligible obese (body mass index ≥30 kg/m(2); n = 505) and non-obese (<30 kg/m(2); n = 494) patients were switched to AML/OM 5/20 mg and uptitrated at 4-week intervals to AML/OM 5/40 mg, AML/OM 10/40 mg, AML/OM 10/40 mg + HCTZ 12.5 mg, and AML/OM 10/40 mg + HCTZ 25 mg. Uptitration to higher doses of AML/OM was permitted if mean seated systolic BP (SeSBP) was ≥120 mmHg, or mean seated diastolic BP (SeDBP) was ≥70 mmHg. HCTZ was added if mean SeSBP was ≥125 mmHg, or mean SeDBP was ≥75 mmHg.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00791258

MAIN OUTCOME MEASURES

The primary efficacy endpoint was the cumulative proportion of patients achieving SeSBP <140 mmHg (<130 mmHg for patients with diabetes mellitus) at 12 weeks. Secondary endpoints included seated cuff BP (SeBP) goal rates, ambulatory BP target rates, and mean change from baseline in SeBP and ambulatory BP at weeks 12 and 20.

RESULTS

At 12 weeks, 71.6% of obese patients (80.2% non-obese) achieved the primary endpoint of cumulative SeSBP <140 mmHg (<130 mmHg for patients with diabetes). The cumulative SeBP goal of <140/90 mmHg (<130/80 mmHg if diabetes) was achieved by 64.8% and 81.2% of obese patients by weeks 12 and 20, respectively (vs. 77.9% and 88.5% of non-obese patients, respectively). Treatment was well-tolerated, with 26.1% of obese patients (24.9% non-obese) experiencing drug-related treatment-emergent adverse events (TEAEs). There were no serious drug-related TEAEs.

CONCLUSION

An AML/OM ± HCTZ treatment regimen provided effective and safe BP control in obese patients with hypertension uncontrolled on monotherapy.

Hyperaldosteronism as a common cause of resistant hypertension

Resistant hypertension affects an estimated 10-15 million American adults and is increasing in prevalence. The etiology of resistant hypertension is almost always multifactorial, including obesity, older age, high dietary salt, chronic kidney disease, and aldosterone excess. Classical primary aldosteronism and lesser degrees of aldosterone excess, possibly originating from visceral adipocytes, contribute broadly to antihypertensive treatment resistance. Treatment of resistant hypertension is predicated on appropriate lifestyle changes and use of effective combinations of antihypertensive agents from different classes. Blockade of aldosterone with spironolactone has been shown to be particularly effective for treatment of resistant hypertension. The antihypertensive benefit of spironolactone is not limited to patients with demonstrable hyperaldosteronism but instead can be effective in resistant hypertensive patients regardless of aldosterone levels. Chlorthalidone is a potent, long-acting thiazide-like diuretic and should be used preferentially to treat resistant hypertension as it is superior to normally used doses of hydrochlorothiazide.

Visceral adipose tissue: emerging role of gluco- and mineralocorticoid hormones in the setting of cardiometabolic alterations

Several clinical and experimental lines of evidence have highlighted the detrimental effects of visceral adipose tissue excess on cardiometabolic parameters. Besides, recent findings have shown the effects of gluco-and mineralocorticoid hormones on adipose tissue and have also underscored the interplay existing between such adrenal steroids and their respective receptors in the modulation of adipose tissue biology. While the fundamental role played by glucocorticoids on adipocyte differentiation and storage was already well known, the relevance of the mineralocorticoids in the physiology of the adipose organ is of recent acquisition. The local and systemic renin–angiotensin–aldosterone system (RAAS) acting on adipose tissue seems to contribute to the development of the cardiometabolic phenotype so that its modulation can have deep impact on human health. A better understanding of the pathophysiology of the adipose organ is of crucial importance in order to identify possible therapeutic approaches that can avoid the development of such cardiovascular and metabolic sequelae.

Uncontrolled hypertension: highlights and perspectives from the European Society of Hypertension Satellite Symposium

The Padua ESH 2011 Satellite Symposium on uncontrolled hypertension was focused on why only a relatively small percentage of patients under treatment do not reach 'safe' blood pressure levels; the major reason being the modest use of combination therapy. It was also an occasion to discuss new pharmacological and nonpharmacological tools, some of which appear to be efficacious when even the 'appropriate' traditional therapeutic strategy fails to work.

Plasma aldosterone is increased in class 2 and 3 obese essential hypertensive patients despite drug treatment

BACKGROUND

The aim of this study was to evaluate whether body mass index (BMI) is independently correlated with plasma aldosterone concentration (PAC) in treated essential hypertensive patients, and whether the relationship between BMI and high blood pressure (BP) can be partially mediated by PAC despite renin-angiotensin-aldosterone system blockade.

METHODS

This study used a cross-sectional design and included 295 consecutive essential hypertensive patients referred to our centre for uncontrolled BP despite stable antihypertensive treatment for at least 6 months. The main exclusion criteria were age >65 years; glomerular filtration rate <30 ml/min; and therapy with mineralocorticoid receptor antagonists, direct renin inhibitors, amiloride or oral contraceptives.

RESULTS

Higher levels of obesity showed a significantly higher mean PAC with a steep nonlinear increase in patients with BMI ≥ 35 kg/m(2). Class 2 and 3 obese patients had a higher mean PAC than nonobese and class 1 obese patients, even in patients under stable treatment with either angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). In a stepwise multiple linear regression model, only log of plasma renin activity (PRA), mean blood pressure (MBP), and class 2 and 3 obesity showed an independent correlation with PAC. In the same model applied to patients treated with ACEIs or ARBs, only logPRA and class 2 and 3 obesity showed a direct correlation with PAC.

CONCLUSIONS

In treated essential hypertensive patients, a BMI ≥ 35 kg/m(2) is independently, albeit modestly, correlated with PAC. The correlation between BMI ≥ 35 kg/m(2) and PAC holds true even in ACEI/ARB-treated patients. Further study is required to determine whether the association of obesity with BP is mediated by PAC in hypertensive patients on stable therapy with ACEIs or ARBs.

Correlation of renin angiotensin and aldosterone system activity with subcutaneous and visceral adiposity: the framingham heart study

BACKGROUND

Animal studies suggest that local adipocyte-mediated activity of the renin-angiotensin-aldosterone system (RAAS) contributes to circulating levels, and may promote the development of obesity-related hypertension in rodents.

METHODS

We examined relations of systemic RAAS activity, as assessed by circulating plasma renin activity (PRA), serum aldosterone level, and aldosterone:renin ratio (ARR), with specific regional adiposity measures in a large, community-based sample. Third Generation Framingham Heart Study participants underwent multidetector computed tomography assessment of SAT and VAT volumes during Exam 1 (2002 and 2005). PRA and serum aldosterone were measured after approximately 10 minutes of supine rest; results were log-transformed for analysis. Correlation coefficients between log-transformed RAAS measures and adiposity measurements were calculated, adjusted for age and sex. Partial correlations between log-transformed RAAS measures and adiposity measurements were also calculated, adjusted for standard CVD risk factors.

RESULTS

Overall, 992 women and 897 men were analyzed (mean age 40 years; 7% hypertension; 3% diabetes). No associations were observed with SAT (renin r = 0.04, p = 0.1; aldosterone r = -0.01, p = 0.6) or VAT (renin r = 0.03, p = 0.2; aldosterone r = -0.03, p = 0.2). Similar results were observed for ARR, in sex-stratified analyses, and for BMI and waist circumference. Non-significant partial correlations were also observed in models adjusted for standard cardiovascular risk factors.

CONCLUSIONS

Regional adiposity measures were not associated with circulating measures of RAAS activity in this large population-based study. Further studies are required to determine whether adipocyte-derived RAAS components contribute to systemic RAAS activity in humans.

Mineralocorticoid receptors in the pathophysiology of chronic kidney diseases and the metabolic syndrome

Recent studies indicate that aldosterone/mineralocorticoid receptor (MR) is a major contributor of chronic kidney disease (CKD) progression. Aldosterone/MR induces glomerular podocyte injury, causing the disruption of the glomerular filtration barrier and proteinuria. Conversely, MR antagonists substantially reduce proteinuria, which can be partly attributable to the protective effects on podocytes. Aldosterone excess, caused by adipocyte-derived aldosterone-releasing factors and other mechanisms, can be pathologically important in the renal complication of metabolic syndrome. A rat model of metabolic syndrome exhibits podocyte injury and proteinuria with serum aldosterone elevation, and the renal damage is prevented by MR blockade. Accumulating data also indicate that MR inhibition can confer renoprotection in a subgroup with low or normal aldosterone levels. We have recently identified the cross-talk between MR and small GTPase Rac1, providing one theoretical basis for the renoprotective effects of MR antagonists in non-high-aldosterone subjects. MR blockade can be a promising strategy for preventing CKD progression, and future clinical trials will conclusively determine the efficacy and tolerability of selective MR inhibition in CKD and metabolic syndrome.

A case of myelolipoma with bilateral adrenal hyperaldosteronism cured after unilateral adrenalectomy

Myelolipomas are adrenal tumors composed of both adipose and hematopoietic tissues which are rarely associated with primary aldosteronism (PA). Here, we report a case of myelolipoma associated with PA. Aldosterone hypersecretion from bilateral adrenal glands had been confirmed by adrenal venous sampling and pathological analyses, but PA was clinically cured after surgical removal of the unilateral adrenal gland together with the myelolipoma that was not producing aldosterone. It is suggested that myelolipomas may release some factors which stimulate aldosterone production in adrenal glands, although further investigation is necessary. Obesity-related hyperaldosteronism might in part participate in generation of hypertension in the present case.

Abdominal obesity is characterized by higher pulse pressure: possible role of free triiodothyronine

Objective. This study examined whether obesity is characterized by higher 24 h mean pulse pressure (24 h mean SBP-24 h mean DBP) and whether free thyroid hormones (FT(3) and FT(4)) have a relationship with 24 h mean pulse pressure. Methods. A total of 231 euthyroid overweight and obese patients, 103 women and 128 men, aged 18-68 yrs, normotensive (n = 69) or with recently developed hypertension (n = 162), never treated with antihypertensive drugs, were investigated. Fasting insulin, TSH, FT(3), FT(4), glucose, and lipid serum concentrations were measured. Waist circumference was measured as an indirect parameter of central fat accumulation. Ambulatory blood pressure monitoring (ABPM) was performed. Results. 24 h mean pulse pressure (PP) showed a significant positive correlation with BMI (P < 0.001), waist circumference (P < 0.001), and FT(3) (P < 0.001) and insulin serum levels (P < 0.05). When a multivariate analysis was performed, and 24 h PP was considered as the dependent variable, and waist circumference, FT(3), insulin, male sex, and age as independent parameters, 24 h mean PP maintained a significant association only with waist circumference (P < 0.001) and FT(3) levels (P < 0.05). Conclusion. Our results suggest that FT(3) per se may contribute to higher pulse pressure in obese subjects.

Plasma aldosterone levels and development of insulin resistance: prospective study in a general population

Aldosterone plays a role in hypertension, and hypertension is prevalent in patients with insulin resistance. Cross-sectional studies have reported that plasma aldosterone levels are higher in patients with insulin resistance. However, it is not known whether plasma aldosterone levels predict the development of insulin resistance. Subjects of the present study were 1235 local residents (490 men and 745 women) who participated in health screenings in Japan in 1999. Plasma aldosterone levels were measured by radioimmunoassay. We investigated the cross-sectional relationship between plasma aldosterone levels and insulin resistance (homeostasis model assessment index ≥1.73 according to the diagnostic criteria used in Japan) in 1088 nondiabetic participants. At the 10-year follow-up, 141 subjects had died, and 260 subjects refused re-examination. We performed a prospective analysis of 564 subjects to predict incident insulin resistance. We found a significant (P<0.001) cross-sectional relationship between plasma aldosterone and homeostasis model assessment index at baseline. In the prospective analysis, a significantly higher (P<0.05) relative risk (1.71 [95% CI: 1.03-2.84]) was observed in the highest tertile versus lowest tertile of plasma aldosterone for the development of insulin resistance, after adjustment for confounding factors. This 10-year prospective study demonstrated that plasma aldosterone levels predicted the development of insulin resistance in a general population.

Renin-Angiotensin-aldosterone system in diabetes and hypertension

Activation of the renin-angiotensin-aldosterone system (RAAS) is the primary etiologic event in the development of hypertension in people with diabetes mellitus. Modulation of the RAAS has been shown to slow the progression and even cause regression of the microvascular and macrovascular complications associated with diabetes mellitus. Early pharmacotherapy with agents that decrease RAAS activation in the adipose tissue have had a dramatic impact on the prevalence of diabetes related complications. Recent data show that preventing the development of "angry fat" can prevent not just hypertension but also type 2 diabetes mellitus and its associated complications. This review updates what is known about angry fat and the role of RAAS inhibition in preventing the metabolic sequelae of local RAAS activation.

The role of aldosterone in the metabolic syndrome

The metabolic syndrome associates metabolic abnormalities such as insulin resistance and dyslipidemia with increased waist circumference and hypertension. It is a major public health concern, as its prevalence could soon reach 30% to 50% in developed countries. Aldosterone, a mineralocorticoid hormone classically involved in sodium balance regulation, is increased in patients with metabolic syndrome. Besides its classic actions, aldosterone and mineralocorticoid receptor (MR) activation affect glucose metabolism, inducing insulin resistance through various mechanisms that involve oxidative stress, inflammation, and downregulation of proteins involved in insulin signaling pathways. Aldosterone and MR signaling exert deleterious effects on the cardiovascular system and the kidney that influence the cardiovascular risk associated with metabolic syndrome. Salt load plays a major role in cardiovascular injury induced by aldosterone and MR signaling. Large multicenter, randomized clinical trials testing the beneficial effects of MR antagonists on cardiovascular events and mortality in patients with metabolic syndrome are needed.

Diagnosis and treatment of primary aldosteronism

A few simple rules can allow physicians to successfully identify many patients with arterial hypertension caused by PA among the so-called essential hypertensive patients. The hyperaldosteronism and the hypokalemia can be cured with adrenalectomy in practically all of these patients. Moreover, in a substantial proportion of them, the blood pressure can be normalized or markedly lowered if a unilateral cause of PA is discovered. Hence, the screening for PA can be rewarding both for the patient and for the clinician, particularly in those cases where hypertension is severe and/or resistant to treatment, in which the removal of an APA can allow blood pressure to be brought under control despite withdrawal of, or a prominent reduction in, the number and doses of antihypertensive medications.

A comprehensive review of the clinical aspects of primary aldosteronism

Primary aldosteronism is much more common than previously thought. The high prevalence of primary aldosteronism, the damage this condition does to the heart, blood vessels and kidneys (which causes a high rate of cardiovascular events), along with the notion that a timely diagnosis followed by an appropriate therapy can correct the arterial hypertension and hypokalemia, justify efforts to search for primary aldosteronism in many patients with hypertension. Most centers can use a cost-effective strategy to screen for patients with primary aldosteronism. By contrast, the identification of primary aldosteronism subtypes, which involves adrenal-vein sampling, should only be undertaken at tertiary referral centers that have experience in performing and interpreting this test. The identification of a curable form of primary aldosteronism can be beneficial for the patient. In some subgroups of patients with hypertension who are at high risk of primary aldosteronism or can benefit most from an accurate diagnosis, an aggressive diagnostic approach is necessary.

The effect of obesity on chronic kidney disease

Overweightness and obesity are associated with many hemodynamic, structural, and histopathologic alterations in the kidney and with metabolic and biochemical changes that predispose to these abnormalities. Consequent to these disorders, these individuals are more likely to develop chronic kidney disease and end-stage renal failure. Overweight and obese people are more prone to develop albuminuria and, for at least some types of kidney disease, a greater amount of albuminuria and more rapid progression of renal failure. These individuals are more likely to develop diabetes mellitus and hypertension. Diabetic nephropathy, hypertensive nephrosclerosis, focal and segmental glomerulosclerosis, renal cell carcinoma, and urate and calcium oxalate urolithiasis are the more common kidney and urological diseases reported in obese people. Preliminary data indicate that many of the clinical and nephropathologic manifestations associated with obesity can be reversed or ameliorated with reductions in body fat induced by dietary energy restriction or surgical procedures that reduce intake and gastrointestinal absorption of calories.

Diagnosis and treatment of primary aldosteronism

Primary aldosteronism involves more than 11% of hypertensive patients who are referred to specialized centers for the diagnosis and treatment of hypertension. If not diagnosed early it causes an excess damage to the heart, vessels and kidney, which translates into an cardiovascular events. Since these ominous consequences can be corrected with a timely diagnosis and an appropriate therapy, physicians should exercise a high degree of alert concerning the possibility that primary aldosteronism is present in hypertensive patients. The purpose of this review is to provide up-dated information on the strategy for case detection, the subtype differentiation and the management of primary aldosteronism.

Arterial hypertension in obesity: relationships with hormone and anthropometric parameters

BACKGROUND

Obesity has been recognized as an independent risk factor for arterial hypertension.

DESIGN

This study was addressed to identify parameters predictive of 24-h mean systolic and/or diastolic blood pressure levels in obesity.

METHODS

A cohort of 180 euthyroid overweight and obese patients, 79 women and 101 men, aged 20-63 years, normotensive (n = 62) or with recently developed hypertension (n = 118), and never treated with antihypertensive drugs, was examined. Waist circumference, fasting insulin, thyroid stimulating hormone (TSH), free thyroxine (FT) FT(3), FT(4), glucose, and lipid (cholesterol, high-density lipoprotein cholesterol and triglyceride) serum concentrations, and 24-h urinary aldosterone and catecholamines were measured. Ambulatory blood pressure monitoring (ABPM) was performed and hypertension was confirmed when 24-h mean systolic blood pressure was ≥125 mmHg and/or 24-h mean diastolic blood pressure was ≥80 mmHg, according to the 2007 European Society of Hypertension and European Society of Cardiology Practice Guidelines for the Management of Arterial Hypertension.

RESULTS

24-h noradrenaline (p < 0.01) and adrenaline (p < 0.05) levels were higher in hypertensive than in normotensive subjects. The odds ratio (OR) was determined by several univariate and multivariate logistic regression analyses to evaluate the predictive factors of high 24-h blood pressure mean values. When subjects with high systolic and/or high diastolic blood pressure levels (n = 118) were compared to individuals with normal systolic and diastolic blood pressure levels (n = 62), multivariate analysis showed an independent association of hypertension with male gender and 24-h noradrenaline levels. When subjects with high systolic blood pressure levels (n = 108) were compared with those with normal systolic blood pressure levels (n = 72), multivariate analysis showed an independent association of high systolic blood pressure with noradrenaline levels. Lastly, when subjects with high diastolic blood pressure levels (n = 87) were compared with those with normal diastolic blood pressure levels (n = 93), multivariate analysis showed an independent negative association between high diastolic blood pressure and body mass index.

CONCLUSIONS

the present study shows that diastolic blood pressure is independently and negatively associated with body mass index in normotensive or with recently discovered hypertension overweight and obese subjects, and never treated with antihypertensive drugs. These results suggest that obesity per se is responsible for a decrease in diastolic blood pressure before hypertensive state becomes stable. This study also confirms that male gender and daily noradrenaline production contribute to hypertension, and to higher systolic blood pressure levels in particular.

The effect of nutrition on blood pressure

The incidence and severity of hypertension are affected by nutritional status and intake of many nutrients. Excessive energy intake and obesity are major causes of hypertension. Obesity is associated with increased activity of the renin-angiotensin-aldosterone and sympathetic nervous systems, possibly other mineralcorticoid activity, insulin resistance, salt-sensitive hypertension and excess salt intake, and reduced kidney function. High sodium chloride intake strongly predisposes to hypertension. Increased alcohol consumption may acutely elevate blood pressure. High intakes of potassium, polyunsaturated fatty acids, and protein, along with exercise and possibly vitamin D, may reduce blood pressure. Less-conclusive studies suggest that amino acids, tea, green coffee bean extract, dark chocolate, and foods high in nitrates may reduce blood pressure. Short-term studies indicate that specialized diets may prevent or ameliorate mild hypertension; most notable are the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in fruits, vegetables, and low-fat dairy products, and the DASH low-sodium diet. Long-term compliance to these diets remains a major concern.

Role of adipokines in obesity-associated hypertension

It has been well documented that obesity is a major risk factor for the development of the hypertensive state. The correlation between body mass index and blood pressure level is well established. Nevertheless, the exact mechanisms which contribute to obesity-related hypertension remain poorly understood. In the last years, we have realized that the white adipose tissue is not just an inert organ for nutrient storage and isolation but rather depending on the body mass index the biggest endocrinological organ. Thus, the possible contribution of adipokines to the blood pressure elevation becomes an attractive hypothesis to explain the hypertensive state that often occurs in obesity. In this review, we consider direct and indirect effects of main adipokines on structural and functional changes in the cardiovascular system.

Greater exercise sweating in obese women with polycystic ovary syndrome compared with obese controls

PURPOSE

We examined estradiol and testosterone effects on thermoregulation in women with and without Polycystic Ovary syndrome (PCOS). We hypothesized that core temperature (Tc) threshold for sweating during exercise is delayed in women with PCOS and that testosterone delays the Tc set point for sweating during exercise.

METHODS

For 16 d, we suppressed estrogens, progesterone, and testosterone with a gonadotropin-releasing hormone antagonist (GnRHant) in seven women with and seven women without PCOS (control); we added 17[beta]-estradiol (0.2 mg.d-1, two patches) on days 4-16 (E2) and testosterone (2.5 mg.d-1, orally) on days 13-16 (E2 + T). Under each hormone condition, subjects cycled in a temperature of 35 degrees C at 60% of age-predicted HRmax for 40 min.

RESULTS

Tc sweating threshold was lower in women in the PCOS group compared with those in the control during GnRHant (37.21 degrees C +/- 0.51 degrees C vs 37.70 degrees C +/- 0.12 degrees C, P < 0.05); neither E2 nor E2 + T influenced the thermoregulatory responses in PCOS. E2 decreased Tc sweating threshold in control (37.06 degrees C +/- 0.69 degrees C, P < 0.05), but E2 + T attenuated this response (37.53 degrees C +/- 0.19 degrees C). Peak sweating rate was greater in women in the PCOS group compared with those in the control group during GnRHant (1.06 +/- 0.47 vs 0.47 +/- 0.11 mg.cm-2.min-1) and E2 + T (0.85 +/- 0.41 vs 0.44 +/- 0.10 mg.cm-2.min-1, P < 0.05). Compared with the control group, total sweat losses were greater in the PCOS group during GnRHant (0.614 +/- 0.189 vs 0.419 +/- 0.098 L) and during E2 + T (0.696 +/- 0.281 vs 0.434 +/- 0.164 L, P < 0.05) but not during E2 (0.639 +/- 0.231 and 0.505 +/- 0.214 L for PCOS and control groups, respectively, P = 0.09).

CONCLUSIONS

Thermoregulation was adequate in women with PCOS; however, the women with PCOS achieved thermoregulation at the expense of producing higher sweat volumes.

Salt, aldosterone, and insulin resistance: impact on the cardiovascular system

Hypertension and type 2 diabetes mellitus (T2DM) are powerful risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD), both of which are leading causes of morbidity and mortality worldwide. Research into the pathophysiology of CVD and CKD risk factors has identified salt sensitivity and insulin resistance as key elements underlying the relationship between hypertension and T2DM. Excess dietary salt and caloric intake, as commonly found in westernized diets, is linked not only to increased blood pressure, but also to defective insulin sensitivity and impaired glucose homeostasis. In this setting, activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS), as well as increased signaling through the mineralocorticoid receptor (MR), result in increased production of reactive oxygen species and oxidative stress, which in turn contribute to insulin resistance and impaired vascular function. In addition, insulin resistance is not limited to classic insulin-sensitive tissues such as skeletal muscle, but it also affects the cardiovascular system, where it participates in the development of CVD and CKD. Current clinical knowledge points towards an impact of salt restriction, RAAS blockade, and MR antagonism on cardiovascular and renal protection, but also on improved insulin sensitivity and glucose homeostasis.

The role of aldosteronism in causing obesity-related cardiovascular risk

A large body of evidence strongly links aldosterone to development and progression of cardiovascular disease, including vascular stiffness, left ventricular hypertrophy, congestive heart failure, chronic kidney disease, and, especially, hypertension. Emerging data suggest that adipocytes may serve as a source of aldosterone, either directly or indirectly, through the release of aldosterone-stimulating factors. If adipocytes are confirmed to have an important contribution to hyperaldosteronism, it would have significant clinical implications in linking aldosterone to obesity-related increases in cardiovascular risk. Such a cause-and-effect situation would then provide the opportunity to reverse that risk with preferential use of aldosterone antagonists in obese patients.

The prevalence of metabolic syndrome and its components in two main types of primary aldosteronism

Metabolic syndrome (MS) is frequent clinical condition in patients with hypertension. Primary aldosteronism (PA) is a common form of secondary hypertension. This study was aimed at investigating the prevalence of the MS and its components in the two major forms of PA, in unilateral aldosterone-producing adenoma (APA) and bilateral aldosterone overproduction because of idiopathic hyperaldosteronism (IHA). The diagnosis of the particular form of PA was based on adrenal venous sampling and/or successful surgery confirmed by histopathological examination. We analyzed clinical and laboratory data from 100 patients with PA (50 patients with IHA and 50 patients with APA) and from 90 patients with essential hypertension (EH). Metabolic profiles of patients with bilateral form of PA (because of IHA) were similar to EH, but differed from those in patients with unilateral form of PA (APA). The prevalence of the MS (62% in IHA, 34% in APA and 56% in EH), the body mass index value (30±4 kg m(-2) in IHA, 27±5 kg m(-2) in APA and 29±5 kg m(-2) in EH) and triglycerides levels (1.9±0.9 mmol l(-1) in IHA,1.4±0.8 mmol l(-1) in APA and 2.01±1.39 mmol l(-1) in EH) were all significantly (P<0.05) higher in IHA compared with APA patients. Metabolic profile of patients with bilateral form of PA (because of IHA) is similar to EH in contrast to unilateral form of PA (APA).

Marked association between obesity and glomerular hyperfiltration: a cross-sectional study in an African population

BACKGROUND

Obesity and African American ethnicity are established independent risk factors for the development of chronic kidney disease. No data exist about the association between obesity and renal hemodynamics in the African region.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

301 nondiabetic participants (97 lean, 108 overweight, and 96 obese) of African descent with a positive family history of hypertension from the Seychelles islands.

PREDICTOR

Body mass index (BMI).

OUTCOMES

Glomerular hyperfiltration, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction.

MEASUREMENTS

GFR and ERPF were measured using inulin and para-aminohippurate clearances, respectively. Participants' baseline demographics, laboratory data, and blood pressure were measured using standard techniques.

RESULTS

The prevalence of glomerular hyperfiltration (defined as GFR >or=140 mL/min) increased across BMI categories (7.2%, 14.8%, and 27.1% for lean, overweight, and obese participants, respectively; P < 0.001). Higher BMI was associated with higher median GFR (99, 110, and 117 mL/min for lean, overweight, and obese participants, respectively; P < 0.001), ERPF (424, 462, and 477 mL/min, respectively; P = 0.01), and filtration fraction (0.23, 0.24, and 0.25; P < 0.001). Multivariate analyses adjusting for age, sex, blood pressure, fasting glucose level, and urinary sodium excretion and accounting for familial correlations confirmed the associations between high BMI (>25 kg/m(2)) and increased GFR, ERPF, and filtration fraction. No association between BMI categories and GFR was found with adjustment for body surface area.

LIMITATIONS

Participants had a positive family history of hypertension.

CONCLUSION

Overweight and obesity are associated with increased GFR, ERPF, and filtration fraction and a high prevalence of glomerular hyperfiltration in nondiabetic individuals of African descent. The absence of associations between BMI categories and GFR indexed for body surface area raises questions regarding the appropriateness of indexing GFR for body surface area in overweight populations.

Adipokines and cardiometabolic profile in primary hyperaldosteronism

CONTEXT

Primary aldosteronism (PA) has been recently associated with an unfavorable cardiometabolic profile. However, whether pro- and antiinflammatory adipokines levels can vary in PA is unknown.

OBJECTIVE

We evaluated the circulating levels of resistin, leptin, and adiponectin, echocardiographic left ventricle (LV) parameters, and the prevalence of metabolic syndrome (SM) in subjects with PA.

PATIENTS

Seventy-five subjects with established diagnosis of PA and 232 consecutive individuals with known or suspected hypertension were enrolled.

MAIN OUTCOME MEASURES

Plasma adipokine levels and echocardiographic parameters were calculated. Prevalence of SM was also estimated.

RESULTS

Among the 75 PA subjects, 37 patients were affected by aldosterone-producing adenoma and 38 by idiopathic hyperaldosteronism; 40 subjects were affected by essential hypertension (EH) and SM (EH SM+); 152 subjects were affected by EH without SM (EH SM-); and 40 subjects were normotensive (NT). Subjects with PA had the highest plasma resistin levels among the four groups (P < 0.01). Plasma resistin concentration was significantly higher in PA subjects when compared with EH SM+ individuals (P < 0.01) and EH SM- subjects (P < 0.01). PA subjects showed the higher LV mass and left atrium than EH individuals, irrespectively of the presence of SM (P < 0.01 for both). Plasma resistin levels was significantly correlated with ejection fraction and LV end-diastolic volume. The prevalence of SM was higher in PA subjects than in those with EH (25.4 vs. 20.3%).

CONCLUSIONS

Our data suggest that elevated aldosterone levels is associated with elevated circulating resistin levels and cardiac morphological changes independently of the presence of SM.

Aldosterone production and insulin resistance in healthy adults

CONTEXT

Aldosterone production is associated with insulin resistance in obese and hypertensive subjects. However, its effect on insulin sensitivity in healthy subjects is not clear.

OBJECTIVE

The objective of this study was to test the hypothesis that increased aldosterone production is associated with lower insulin sensitivity in healthy subjects.

DESIGN

This is an analysis of data previously collected during studies conducted as part of the International Hypertensive Pathotype Consortium.

PARTICIPANTS AND INTERVENTIONS

Eighty-four subjects free of any medical or psychiatric illness were included in this study. They were studied after 7 d of a standardized high-sodium diet confirmed by 24-h urine sodium above 200 mEq. Insulin sensitivity index (ISI) was calculated after a 75-g oral glucose load with glucose and insulin measurements at 0, 30, 60, and 120 min. Serum aldosterone levels were measured after 45 min of angiotensin II (3 ng/kg/min) infusion.

RESULTS

There were significant negative correlations between ISI and age, body mass index (BMI), diastolic blood pressure, and angiotensin II-stimulated aldosterone level (P < 0.01). On multivariate regression analysis, stimulated aldosterone level was an independent predictor of ISI after adjusting for age, BMI, and diastolic blood pressure. Stimulated aldosterone level predicted 8% of the variance in ISI (P = 0.003) with age, BMI, and diastolic blood pressure together predicting 23% of the variance in ISI. Thus, the final regression model predicted 31% of the variance in ISI (P < 0.0001).

CONCLUSIONS

Aldosterone production is associated with insulin resistance in normotensive healthy subjects independent of traditional risk factors.

Effect of body weight loss and normalization on blood pressure in overweight non-obese patients with stage 1 hypertension

We evaluated the effects of body weight (BW) loss on blood pressure (BP) in overweight non-obese patients with stage 1 hypertension. We enrolled 376 overweight (body mass index (BMI) >or=25 and <30 kg m(-2)) stage 1 hypertensive patients in this prospective 12-month trial. Each patient received tailored, low caloric dietary advice. After 6 months, patients with a BW reduction <5% were excluded. Body weight, BMI, BP, fasting plasma glucose (FPG), fasting plasma insulin (FPI), leptin (pL), renin and aldosterone levels were evaluated at baseline and after 6 and 12 months. In 222 patients who completed the study, a mean weight reduction of 8.1 kg reduced systolic blood pressure (SBP) by 4.2 mm Hg and diastolic blood pressure (DBP) by 3.3 mm Hg (P<0.05), which was accompanied by a significant decrease in FPI, pL and aldosterone levels (P<0.05). Larger SBP/DBP reductions were observed in 106 patients with normalized BMI (-5/-4.5 mm Hg, P<0.01) compared with the 116 patients who did not become normalized (-3.3/-1.6 mm Hg). The former also presented with greater decreases in FPG, FPI, pL, renin and aldosterone levels. Of the 106 patients who had normalized BMI, 52 also had normalized BP. Clinical and metabolic characteristics of these patients were similar to those of the 56 patients who did not have normalized BP. In overweight, mild hypertensive patients, weight loss was effective in reducing BP and in reversing some endocrinologic alterations associated with being overweight. Half of the patients who had normalized BMI also had normalized BP, which could indicate that these patients essentially did not have a form of hypertension but that these effects were instead secondary to being overweight.

Aldosterone contributes to blood pressure variance and to likelihood of hypertension in normal-weight and overweight African Americans

BACKGROUND

Hypertension and obesity are highly prevalent among African Americans (AAs). We have previously reported that both plasma aldosterone (PA) and body mass index (BMI) are higher in hypertensive than in normotensive AAs. This study evaluates the relative contributions of adiposity and PA to hypertension in AAs.

METHODS

A total of 466 AAs (50% hypertensive, 51% women) were evaluated in a Clinical Research Center by stratifying them into three subgroups based on BMI (normal weight, overweight, and obese). Anthropometric measurements, ambulatory blood pressure (BP), fasting glucose, insulin, 24-h urine sodium and potassium, creatinine clearance, standing PA and plasma renin activity (PRA) were measured. Insulin resistance was estimated by the homeostasis model assessment.

RESULTS

Compared to normotensives, hypertensives had higher BMI, waist circumference (WC), and were more insulin resistant (P < or = 0.01). When stratified by BMI, hypertensives in each BMI strata had higher PA (P < or = 0.05) and lower PRA (P < or = 0.01) compared to normotensives. Compared to normotensives, WC was greater in overweight and obese hypertensives, but not in normal-weight hypertensives. In the overall sample, age, WC, PA, and PRA were the major contributors to BP variance and to hypertension. Among normal-weight subjects, PA and PRA significantly predicted BP and the odds ratio for hypertension, whereas WC had no predictive value.

CONCLUSIONS

PA, but not WC, is associated with BP and likelihood of hypertension in normal-weight AAs, whereas both WC and PA are predictive of hypertension in overweight and obese individuals. This suggests that aldosterone antagonists may be useful for the treatment of hypertension among AAs, regardless of BMI.

Increased aldosterone among HIV-infected women with visceral fat accumulation

Increased aldosterone has been associated with obesity and the metabolic syndrome in non-HIV-infected individuals, but aldosterone has not been investigated among HIV-infected patients with increased visceral adipose tissue (VAT). Twenty-four-hour urine aldosterone was assessed among age and BMI-matched HIV-infected women with increased VAT, HIV-infected women without increased VAT and healthy controls. Twenty-four hour urine aldosterone was higher in HIV-infected women with increased VAT and was associated with SBP, VAT and hemoglobin A1c. Increased aldosterone may contribute to the detrimental effects of excess visceral adiposity on blood pressure and glucose homeostasis among HIV patients.

Manifestation of renal disease in obesity: pathophysiology of obesity-related dysfunction of the kidney

Albuminuria in individuals whose body mass index exceeds 40 kg/m(2) is associated with the presence of large glomeruli, thickened basement membrane and epithelial cellular (podocyte) distortion. Obstructive sleep apnea magnifies glomerular injury as well, probably through a vasoconstrictive mechanism. Insulin resistance from excess fatty acids is exacerbated by decreased secretion of high molecular weight adiponectin from adipose cells in the obese state. Adiponectin potentiates insulin in its post-receptor signaling resulting in glucose oxidation in mitochondria. Recent studies of podocyte physiology have concentrated on the structural and functional requirements that prevent glomerular albumin leakage. The architecture of the podocyte involves nephrin and podocin, proteins that cooperate to keep slit pores between foot processes competent to retain albumin. Insulin and adiponectin are necessary for high-energy phosphate generation. When fatty acids bind to albumin, the toxicity to proximal renal tubules is magnified. Albumin and fatty acids are elevated in urine of individuals with obesity related nephrotic syndrome. Fatty acid accumulation and resistin inhibit insulin and adiponectin. Study of cytokines produced by adipose tissue (adiponectin and leptin) and macrophages (resistin) has led to a better understanding of the relationship between weight and hypertension. Leptin, is presumably secreted after food intake to inhibit the midbrain/hypothalamic appetite centers. Resistance to leptin results in excess signaling to hypothalamic sympathetics leading to hypertension. Demonstration of the existence of a cerebral receptor mutation provide evidence for a role in hypertension of a central nervous reflex arc in humans. Further understanding of obesity-related renal dysfunction has been accomplished recently using experimental models. Rapid weight loss following bariatric surgery may reverse renal pathology of obesity with restoration of normal blood pressure.

Alcohol consumption is associated with decreased insulin resistance independent of body mass index in Japanese community-dwelling men

Alcohol consumption is associated with a decreased risk of type II diabetes and cardiovascular diseases. However, there is a great deal of controversy concerning the relationship between alcohol consumption and insulin resistance. This association may be further confounded by an increase in body weight levels. The aim of this study was to determine whether alcohol consumption promotes insulin resistance according to body weight levels in community-dwelling men. Study participants without a clinical history of stroke, transient ischemic attack, myocardial infarction, angina or diabetes were randomly recruited from a single community at the time of their annual health examination (678 men aged 59 +/- 14 years). They were classified into never drinkers, light drinkers [< 1 unit (22.9 g ethanol)/day], moderate drinkers (1-1.9 unit/day), and heavy drinkers (> or = 2 unit/day), and further divided into underweight [body mass index (BMI) < 23 kg/m(2)] or overweight (BMI > or = 23.0 kg/m(2)). Insulin resistance was estimated on the basis of the homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA-IR and potential confounders were compared between the groups. The confounders included age, BMI, smoking status, serum gamma glutamyltransferase, and high molecular-weight adiponectin. In the overall, HOMA-IR is significantly correlated with age, BMI, serum gamma glutamyltransferase, and high molecular-weight adiponectin. After adjustment for potential confounders, mean log HOMA-IR is significantly lower in the heavy drinkers irrespective of BMI categories. In conclusion, alcohol consumption is associated with decreased insulin resistance independent of BMI in Japanese community-dwelling men.

Role of aldosterone and angiotensin II in insulin resistance: an update

The role of the Renin-Angiotensin-Aldosterone system (RAAS) on the development of insulin resistance and cardiovascular disease is an area of growing interest. Most of the deleterious actions of the RAAS on insulin sensitivity appear to be mediated through activation of the Angiotensin II (Ang II) Receptor type 1 (AT(1)R) and increased production of mineralocorticoids. The underlying mechanisms leading to impaired insulin sensitivity remain to be fully elucidated, but involve increased production of reactive oxygen species and oxidative stress. Both experimental and clinical studies also implicate aldosterone in the development of insulin resistance, hypertension, endothelial dysfunction, cardiovascular tissue fibrosis, remodelling, inflammation and oxidative stress. There is abundant evidence linking aldosterone, through non-genomic actions, to defective intracellular insulin signalling, impaired glucose homeostasis and systemic insulin resistance not only in skeletal muscle and liver but also in cardiovascular tissue. Blockade of the different components of the RAAS, in particular Ang II and AT(1)R, results in attenuation of insulin resistance, glucose homeostasis, as well as decreased cardiovascular disease morbidity and mortality. These beneficial effects go beyond to those expected with isolated control of hypertension. This review focuses on the role of Ang II and aldosterone in the pathogenesis of insulin resistance, as well as in clinical relevance of RAAS blockade in the prevention and treatment of the metabolic syndrome and cardiovascular disease.

The renin angiotensin aldosterone system in hypertension: roles of insulin resistance and oxidative stress

The relationship between HTNand other components of the CMSis complex. However, there is growing evidence that enhanced activation of the RAAS is a key factor in the development of endothelial dysfunction and HTN. Insulin resistance is induced by activation of the RAAS and resulting increases in ROS. This insulin resistance occurs in cardiovascular tissue and in tissues traditionally considered as targets for the action of insulin, such as muscle and liver. Indeed, there is a mounting body of evidence that the resultant insulin resistance in cardiovascular tissue and kidneys contributes to the development of endothelial dysfunction, HTN, atherosclerosis, CKD, and CVD.77 RAAS-associated signaling by way of the AT1R and MR, triggers tissue activation of the NADPH oxidase enzymatic activation and increased production of ROS. Oxidative stress in cardiovascular tissue is derived from both NADPH oxidase and mitochondrial generation of ROS, and is central to the development of insulin resistance, endothelial dysfunction, HTN, and atherosclerosis. Pharmacologic blockade of the RAAS not only improves blood pressure, but alsohas a beneficial impact on inflammation, oxidative stress, insulin sensitivity, and glucose homeostasis. Several strategies are available for RAAS blockade, including ACE inhibitors, ARBs, and MR blockers, which have been proven in the clinical trials to result in improved CVD and CKD outcomes. New research in these areas will allow for a better understanding of the relationship between HTN, insulin resistance, and activation of the RAAS, which could result in newer alternatives for a more comprehensive management of HTN in the setting of the CMS..

Interaction of aldosterone and extracellular volume in the pathogenesis of obesity-associated kidney disease: a narrative review

Obesity and obesity-associated kidney injuries have played an important role in the rising prevalence of chronic kidney disease (CKD). The link between obesity and kidney disease begins with obesity's well-known associations with diabetes and hypertension, the two leading etiologies of CKD. However, a growing body of evidence suggests that elevated aldosterone levels and expanded extracellular volume are key components of obesity-induced renal disease via aldosterone's non-epithelial effects on the kidney. Highlighting these blood pressure- and diabetes-independent mechanisms of kidney injury in obesity allows an exploration of whether mineralocorticoid receptor blockade, coupled with weight loss and salt restriction, is an optimal treatment for overweight CKD patients.

Renin-angiotensin-aldosterone responsiveness to low sodium and blood pressure reactivity to angiotensin-II are unrelated to cholesteryl ester transfer protein mass in healthy subjects

BACKGROUND

The blood pressure increase associated with the cholesteryl ester transfer protein (CETP) inhibitor, torcetrapib is probably attributable to an off-target effect but it is unknown whether activation of the renin-angiotensin-aldosterone system (RAAS) may be related to variation in the plasma CETP level. We questioned whether the plasma CETP level would affect RAAS responsiveness to low sodium diet and the blood pressure response to angiotensin-II infusion in healthy subjects.

METHODS

RAAS parameters and blood pressure were determined during liberal sodium diet (200 mmol/24 h) and low sodium diet (50 mmol/24 h) in 67 healthy men. Blood pressure response to incremental angiotensin-II infusion was assessed in 34 subjects during liberal sodium diet. Correlation analysis was performed to test whether RAAS responsiveness and blood pressure were related to plasma CETP mass, high-density lipoprotein-cholesterol (HDL-C) and apolipoprotein A-I measured during liberal sodium diet.

RESULTS

CETP mass ranged from 1.29 to 2.95 mg/l. No significant differences in (changes) in mean arterial pressure, aldosterone and active plasma renin concentration in response to low sodium were observed between the lowest and highest tertiles of CETP mass, HDL-C and apolipoprotein A-I. These outcome variables were also not significantly correlated with CETP, HDL-C and apolipoprotein A-I, except for a modest relation of aldosterone measured during low sodium with apolipoprotein A-I (r = 0.28, p = 0.022). Blood pressure response to angiotensin-II was similar between CETP tertiles.

CONCLUSIONS

Mineralocorticoid and blood pressure responsiveness to dietary salt intake are not significantly related to physiological interindividual differences in plasma CETP. We suggest that a lower CETP mass does not exert adverse effects on blood pressure regulation.