Obesity, hypertension, and the heart

Clinical and psychological responses to synbiotic supplementation in obese or overweight adults: A randomized clinical trial

BACKGROUND

Obesity is highly prevalent worldwide. Emerging clinical studies suggest that pre- and pro- biotic formulations may be effective interventions for the management of obesity and associated metabolic complications. The current trial was conducted to assess the effect of synbiotic supplementation on anthropometric indices, glycemic and lipid profile, blood pressure, and psychological status of adults with overweight or obesity.

METHODS

This randomized double-blind, placebo-controlled trial was conducted on 60 adults with overweight or obesity. Participants were randomly assigned into two groups to receive either synbiotics (n = 30) in form of a 500 mg capsule (containing Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum plus inulin) or placebo (n = 30) for 8 weeks. The level of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FPG), insulin, body weight, body mass index (BMI), waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), stress, anxiety, and depression were measured at the baseline and end of the study.

RESULTS

In total, 59 subjects (39 men and 20 women) completed the present study. A significant between-group decrease in body weight (P = 0.03), TC (P = 0.01), TG (P = 0.02), LDL-C (P = 0.01), stress (P < 0.001), anxiety (P = 0.03), and depression (P = 0.03) was found in the synbiotic group compared to the placebo. However, synbiotics had no significant effect on HDL-C, SBP, DBP, FPG and fasting insulin concentrations, as well the BMI and WC (P < 0.05).

CONCLUSION

The present study showed that synbiotic supplementation can confer a number of health benefits including improvements in TG, TC, LDL-C, body weight, stress, anxiety, and depression to subjects that are overweight or obesity.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20180201038585N3.

Cardiac Effects of Obesity: PATHOPHYSIOLOGIC, CLINICAL, AND PROGNOSTIC CONSEQUENCES-A REVIEW

Obesity produces various hemodynamic alterations and changes in cardiac morphology that predispose to ventricular dysfunction and heart failure (HF). Obesity may serve as a risk factor for or the primary cause of HF. Obesity is also associated with impairment of cardiorespiratory fitness. An obesity paradox exists with respect to mortality in those with HF wherein overweight and mildly to moderately obese individuals have a better prognosis than underweight or normal weight persons. Cardiorespiratory fitness is an important determinant of the prognosis in obesity. Many of the alterations in cardiac structure and function as well as the clinical manifestations of HF are reversible with substantial weight loss in moderately to severely obese individuals.

Differences in Vascular Reactivity Between Men and Women

The purpose of this study was to compare the gender and age-related differences in vascular reactivity in healthy men and women across a wide age range. Fifty-seven men and 61 women between 20 and 89 years of age, free of cardiovascular disease and risk factors, were categorized into younger (20-39 years), middle-aged (40-59 years), and older (60-89 years) age groups. Subjects were characterized on body weight and height, body mass index (BMI), and calf blood flow under resting, postocclusive reactive hyperemic (PORH), and maximal hyperemic conditions in the lower extremity with use of venous occlusion mercury strain-gauge plethysmography. Similar baseline characteristics were observed among age groups, whereas men had greater body weight (p<0.05), higher BMI values (p<0.05), and a trend toward higher ankle-brachial index (ABI) values (p=0.054) than women. While calf blood flow measurements were similar for men and women at rest and at maximal hyperemic conditions, women had a greater percentage change in calf blood flow from rest to PORH than men (p=0.046). After adjusting for body weight, BMI, and ABI, the percentage change in calf blood flow from rest to PORH was no longer significantly higher in the women (p>0.05). Furthermore, the percentage change in calf blood flow from rest to PORH was negatively related to body weight ( r = -0.30, p<0.01) and to BMI ( r = -0.26, p<0.01) in the men and women. No differences (p>0.05) in the calf blood flow measures were observed among the age groups. In a healthy cohort free of cardiovascular disease, increased BMI accounted for poorer vascular reactivity in men compared to women regardless of age.

Roux-en-Y gastric bypass alleviates hypertension and is associated with an increase in mid-regional pro-atrial natriuretic peptide in morbid obese patients

OBJECTIVE

To examine 24-h blood pressure (24BP), systemic haemodynamics and the effect of sodium intake on 24BP in obese patients before and after gastric bypass surgery [laparoscopic Roux-en-Y gastric bypass (LRYGB)], and to determine whether weight loss from LRYGB might be related to an increase in plasma concentrations of atrial natriuretic peptide.

METHODS

Twelve hypertensive and 12 normotensive morbidly obese patients underwent LRYGB: 24BP, systemic haemodynamics and mid-regional pro-atrial natriuretic peptide (MRproANP) were assessed before, 6 weeks and 12 months after surgery. The effect of high versus low sodium intake on 24BP was evaluated before and 12 months after LRYGB.

RESULTS

Six weeks after LRYGB, the average weight loss was 20 kg, with a further 21 kg weight loss 1 year after surgery. In hypertensive patients, 24BP was significantly reduced at 6 weeks, but not 1 year after LRYGB. However, antihypertensive medications were successively reduced from baseline to 1 year after surgery. In normotensive patients, there was no change in 24BP 6 weeks after LRYGB, but a tendency towards a reduction 1 year after the operation. Plasma concentrations of MRproANP were subnormal prior to surgery in hypertensive patients and increased by 77% 1 year after the operation. In normotensive patients, preoperative concentrations were normal and increased only by 6%. High sodium intake induced plasma volume expansion, increased stroke volume and cardiac output, but no significant change in 24BP - neither before nor after LRYGB.

CONCLUSIONS

LRYGB resulted in a significant 24BP reduction and a substantial increase in MRproANP plasma concentrations in hypertensive, obese patients 6 weeks after surgery, suggesting a causal link between obesity-hypertension and altered release/degradation of cardiac natriuretic peptides.

The influence of high versus low sodium intake on blood pressure and haemodynamics in patients with morbid obesity

BACKGROUND

Many patients with morbid obesity (BMI > 40 kg/m) have hypertension. The complex pathophysiological abnormalities linking hypertension to obesity have not been fully clarified, but abnormal sodium handling could be an important mechanism.

METHOD

Therefore, we examined changes in body fluid compartments and haemodynamic responses (at rest and during exercise) after 5 days of a low-sodium diet (90 mmol/day) and 5 days of a high-sodium diet (250 mmol/day) in 12 morbidly obese, hypertensive patients; 12 morbidly obese, normotensive patients and 12 nonobese controls.

RESULTS

High sodium intake as compared to low sodium intake was associated with an increase in plasma volume (obese, hypertensive patients: 5 ± 4%; obese, normotensive patients: 10 ± 11%; nonobese controls: 7 ± 6%), cardiac output (CO) (obese, hypertensive patients: 17 ± 12%; obese, normotensive patients: 20 ± 16%; nonobese controls: 13 ± 14%) and stroke volume (SV) (obese, hypertensive patients: 27 ± 26%; obese, normotensive patients: 27 ± 24%; nonobese controls: 18 ± 27%) in all three groups with no differences between the groups. Despite an increase in CO during high salt intake, 24-h blood pressure (BP) was unchanged in patients and controls as a result of a reduction in total peripheral resistance (obese, hypertensive patients: -11 ± 11%; obese, normotensive patients: -10 ± 12%; nonobese controls: -5 ± 14%). Similar changes were observed during an incremental bicycle exercise test wherein CO and SV were higher, whereas mean arterial BP was unchanged at each exercise level during high sodium intake.

CONCLUSION

Despite substantial increases in CO and SV, we did not observe any significant change in BP during high sodium intake, neither in morbid obese patients nor in lean individuals.

Long-Term Regulation of the Local Renin-Angiotensin System in the Myocardium of Spontaneously Hypertensive Rats by Feeding Bioactive Peptides Derived from Spirulina platensis

This study investigated the long-term (8 weeks) anti-hypertensive effects of 10 mg/kg tripeptides isolated from Spirulina platensis, Ile-Gln-Pro (IQP) and Val-Glu-Pro (VEP), and S. platensis hydrolysates (SH) on spontaneously hypertensive rats. The treatment period was 6 weeks, and observation continued for another 2 weeks. After treatment, weighted systolic blood pressure, weighted diastolic blood pressure, left ventricular mass index, and right ventricular mass index of groups treated with IQP, VEP, and SH were significantly lower than those of the group treated with distilled water, even when the treatments had been withdrawn for 2 weeks. Quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting showed the mRNA expression levels and protein/peptide concentrations of the main components of the renin angiotensin system in myocardium were significantly affected by treatment: angiotensin converting enzyme, angiotensin II, and angiotensin type 1 receptor were down-regulated, whereas angiotensin type 2 receptor, angiotensin converting enzyme 2, angiotensin-(1-7), and Mas receptor were up-regulated.

Sudden cardiac death and obesity

For individuals and the society as a whole, the increased risk of sudden cardiac death in obese patients is becoming a major challenge, especially since obesity prevalence has been increasing steadily around the globe. Traditional risk factors and obesity often coexist. Hypertension, diabetes, obstructive sleep apnea and metabolic syndrome are well-known risk factors for CV disease and are often present in the obese patient. Although the bulk of evidence is circumstantial, sudden cardiac death and obesity share common traditional CV risk factors. Structural, functional and metabolic factors modulate and influence the risk of sudden cardiac death in the obese population. Other risk factors such as left ventricular hypertrophy, increased number of premature ventricular complexes, altered QT interval and reduced heart rate variability are all documented in both obese and sudden cardiac death populations. The present review focuses on out-of-hospital sudden cardiac death and potential mechanisms leading to sudden cardiac death in this population.

Left ventricular remodeling and diastolic function in chronic hypertensive pregnant women

Hypertension during pregnancy is a problem that impacts maternal morbidity and mortality. Dyspnea and edema are common symptoms, often secondary to physiological changes, but may raise doubts as to ventricular dysfunction.

OBJECTIVE

To evaluate the ventricular geometry pattern and diastolic function in chronic hypertensive pregnant women (HPW).

METHODS

Prospective, cross-sectional study on 62 pregnant women over a 29-month period, from March 2009 to July 2011, in Brazil was done. Thirty-one HPWs and 31 normotensive pregnant women (NPW) underwent clinical and cardiovascular evaluations, and were subjected to transthoracic echocardiogram.

RESULTS

LV mass (HPW: 220.9 ± 43.3 vs. NPW: 192.9 ± 39.8 g, p = 0.01), posterior wall thickness (HPW: 9.9 ± 1.1 vs. NPW: 9.2 ± 0.9 mm, p = 0.005), mitral flow A wave velocity (HPW: 0.60 ± 0.16 vs. NPW: 0.52 ± 0.10 m/s, p = 0.02), tissue Doppler A' wave velocity (HPW: 10 ± 2 vs. NPW: 8.9 ± 1cm/s, p=0.02), and E/E' ratio (HPW: 6.8 ± 2.2 vs. NPW: 5.5 ± 1.6, p = 0.01) were higher in HPWs. Septal and lateral walls E' wave velocities (HPW: 13 ± 2 vs. NPW: 15 ± 3 cm/s, p=0.001), and E'/A' ratio (HPW: 1.26 ± 0.38 vs. NPW: 1.77 ± 0.49, p = 0.00003) were lower in HPWs. There was a positive linear correlation between body mass index (BMI) and ventricular mass, A wave, systolic, diastolic blood pressures, and a negative correlation between BMI, E' wave and E'/A' ratio.

CONCLUSION

Ventricular remodeling showed a direct relationship with body weight, and both groups showed a predominant pattern of eccentric ventricular hypertrophy. The LV diastolic function was abnormal in HPWs.

Obesity and heart failure: epidemiology, pathophysiology, clinical manifestations, and management

Obesity is a risk factor for heart failure (HF) in both men and women. The mortality risk of overweight and class I and II obese adults with HF is lower than that of normal weight or underweight adults with HF of comparable severity, a phenomenon referred to as the obesity paradox. Severe obesity produces hemodynamic alterations that predispose to changes in cardiac morphology and ventricular function, which may lead to the development of HF. The presence of systemic hypertension, sleep apnea, and hypoventilation, comorbidities that occur commonly with severe obesity, may contribute to HF in such patients. The resultant syndrome is known as obesity cardiomyopathy. Substantial weight loss in severely obese persons is capable of reversing most obesity-related abnormalities of cardiac performance and morphology and improving the clinical manifestations of obesity cardiomyopathy.

Management of obesity cardiomyopathy

Obesity causes a variety of hemodynamic alterations that may lead to changes in cardiac structure and function. Although such abnormalities may occur in patients with mild-to-moderate obesity, they are most pronounced in those with morbid obesity. When these alterations produce congestive heart failure, obesity cardiomyopathy is said to be present. In this review, the authors will first discuss the pathogenesis and clinical manifestations of obesity cardiomyopathy and then describe the management of this clinical syndrome with emphasis on the effects of weight reduction.

The heart in obesity-hypertension

There is growing recognition that obesity is reaching epidemic proportions throughout the world. In adults, obesity is associated with increased cardiovascular morbidity and mortality. A series of endocrine, metabolic and hemodynamic mechanisms have been responsible for the development of obesity-hypertension. These mechanisms include: a suppressed biologic activity and availability of natriuretic peptide, increased sympathetic adrenergic activity, release of angiotensin ll from adipocytes and activation of the renin-angiotensin-aldosterone system, leptin resistance, chronic hyperleptinemia and hyperinsulinemia. The systemic hemodynamic profile of obesity includes high intravascular volume, increased cardiac output and inappropriately normal peripheral resistance. The cardiovascular adaptations to these changes include changes in vascular responsiveness and concentric-eccentric left ventricular hypertrophy, and may be responsible for increased risk of congestive heart failure, arrhythmia and sudden death.

Abnormal amounts of intracellular calcium regulatory proteins in SHRSP.Z-Leprfa/IzmDmcr rats with metabolic syndrome and cardiac dysfunction

Metabolic syndrome is known to increase the risk of abnormal cardiac structure and function, which are considered to contribute to increased incidence of cardiovascular disease and mortality. We previously demonstrated that ventricular hypertrophy and diastolic dysfunction occur in SHRSP.Z-Leprfa/IzmDmcr (SHRSP fatty) rats with metabolic syndrome. The aim of this study was to investigate the possible mechanisms underlying abnormal heart function in SHRSP fatty rats. The amount of sarcoplasmic reticulum Ca2+-ATPase (SERCA) 2a, phospholamban (PLB) protein, and Ser16-phosphorylated PLB was decreased in cardiomyocytes from SHRSP fatty rats compared with those from control Wistar–Kyoto rats at 18 weeks of age, and the PLB-to-SERCA2a ratio was increased. Left ventricular developed pressure was unchanged, and coronary flow rate and maximum rate of left ventricular pressure decline (−dP/dt) was decreased in SHRSP fatty rats. Treatment with telmisartan reversed the abnormalities of PLB amount, coronary flow rate, and −dP/dt in SHRSP fatty rats. These results indicate that abnormal amounts of intracellular Ca2+ regulatory proteins in cardiomyocytes, leading to reduced intracellular Ca2+ reuptake into the sarcoplasmic reticulum, may play a role in the diastolic dysfunction in SHRSP fatty rats and that these effects are partially related to decreased coronary circulation. Telmisartan may be beneficial in protecting against disturbances in cardiac function associated with metabolic syndrome.

Obese patients show a depressed cytokine profile following severe blunt injury

We hypothesized that severely injured obese patients would display increased concentrations of proinflammatory cytokines when compared with patients of normal body mass index (BMI) and that this would be associated with multiple organ failure (MOF). This was a retrospective review of prospectively collected data in the "Inflammation and the Host Response to Injury" trauma-related database. Data were collected prospectively from US level I trauma centers. The subjects were severely injured adult blunt trauma patients. Cytokine concentrations obtained within 12 h of injury and on days 1 and 4 were compared between subjects on the basis of BMI (normal, 18.5-24.9 kg/m, and obese, ≥30 kg/m). Demographic measures, injury severity, cytokine concentrations, and outcome measures were compared between groups. Seventy-four adult blunt trauma victims were evaluated. Relative to patients of normal BMI (n = 34), obese patients (n = 40) demonstrated an overall depressed cytokine response to severe injury, with significantly lower concentrations of several cytokines. Obese patients showed greater incidences of nosocomial infection (60 vs. 45%, not statistically significant) and MOF (63% vs. 44%, not statistically significant) and a later onset of maximum MOF score (5 vs. 3 days, P < 0.04) when compared with those of normal BMI. Despite prior reports suggesting a proinflammatory cytokine profile in obese individuals, obese patients sustaining severe injury show a depressed early cytokine response when compared with patients of normal BMI. This may confer increased susceptibility to nosocomial infection and later MOF. Further study of immune dysfunction in the postinjury obese patient should assess the possibility of early immune suppression.

The role of the mineralocorticoid receptor in adipocyte biology and fat metabolism

Aldosterone controls blood pressure by binding to the mineralocorticoid receptor (MR), a ligand-activated transcription factor which regulates critical genes controlling salt and water homeostasis in the kidney. In recent years, inappropriate MR activation has been shown to trigger deleterious responses in various tissues, including vessels, heart and brain, hence promoting vascular inflammation, cardiovascular remodeling, endothelial dysfunction, and oxidative stress. Moreover, epidemiological studies have shown a clear association between aldosterone levels and the incidence of metabolic syndrome. In particular, recent work has revealed functional MRs in adipose tissue, where they mediate the effects of aldosterone and glucocorticoids, displaying important and specific functions involving adipose differentiation, expansion and proinflammatory capacity. This recent evidence finally moved MR out of the shadow of the glucocorticoid receptor (GR), which had previously been considered the only player mediating corticosteroid action in adipose tissue. This has opened a new era of research focusing on the complexity and selectivity of MR function in adipocyte biology. The aim of this review is to summarize the latest concepts on the role of MR in white and brown adipocytes, and to discuss the potential benefits of tissue-selective MR blockade in the treatment of obesity and metabolic syndrome.

Role of mineralocorticoid receptor/Rho/Rho-kinase pathway in obesity-related renal injury

OBJECTIVE:

We examined whether aldosterone/Rho/Rho-kinase pathway contributed to obesity-associated nephropathy.

SUBJECTS:

C57BL/6J mice were fed a high fat or low fat diet, and mice on a high fat diet were treated with a mineralocorticoid receptor antagonist, eplerenone.

RESULTS:

The mice on a high fat diet not only developed obesity, but also manifested renal histological changes, including glomerular hypercellularity and increased mesangial matrix, which paralleled the increase in albuminuria. Furthermore, enhanced Rho-kinase activity was noted in kidneys from high fat diet-fed mice, as well as increased expressions of inflammatory chemokines. All of these changes were attenuated by eplerenone. In high fat diet-fed mice, mineralocorticoid receptor protein levels in the nuclear fraction and SGK1, an effector of aldosterone, were upregulated in kidneys, although serum aldosterone levels were unaltered. Furthermore, aldosterone and 3β-hydroxysteroid dehydrogenase in renal tissues were upregulated in high fat diet-fed mice. Finally, in cultured mesangial cells, stimulation with aldosterone enhanced Rho-kinase activity, and pre-incubation with eplerenone prevented the aldosterone-induced activation of Rho kinase.

CONCLUSION:

Excess fat intake causes obesity and renal injury in C57BL/6J mice, and these changes are mediated by an enhanced mineralocorticoid receptor/Rho/Rho-kinase pathway and inflammatory process. Mineralocorticoid receptor activation in the kidney tissue and the subsequent Rho-kinase stimulation are likely to participate in the development of obesity-associated nephropathy without elevation in serum aldosterone levels.

Arterial hypertension and metabolic syndrome: specifics of antihypertensive therapy

This review summarizes the literature evidence on humoral disturbances in arterial hypertension (AH), as well as on AH interrelationship with individual components of metabolic syndrome (MS). Based on the results of multi-centre randomised trials, the rationale for the use of antihypertensive agents with favourable metabolic profile is demonstrated, in particular, for antagonists of slow calcium channels, angiotensin-converting enzyme inhibitors, and selective imidazoline receptor agonists.

Macrophage activation is responsible for loss of anticontractile function in inflamed perivascular fat

OBJECTIVE

The aim of this study was to determine whether macrophages dispersed throughout perivascular fat are crucial to the loss of anticontractile function when healthy adipose tissue becomes inflamed and to gain an understanding of the mechanisms involved.

METHODS AND RESULTS

Pharmacological studies on in vitro small arterial segments from a mouse model of inducible macrophage ablation and on wild-type animals were carried out with and without perivascular fat using 2 physiological stimuli of inflammation: aldosterone and hypoxia. Both inflammatory insults caused a similar loss of anticontractile capacity of perivascular fat and increased macrophage activation. Aldosterone receptor antagonism and free radical scavengers were able to restore this capacity and reduce macrophage activation. However, in a mouse deficient of macrophages CD11b-diptheria toxin receptor (CD11b-DTR), there was no increase in contractility of arteries following aldosterone incubation or hypoxia.

CONCLUSIONS

The presence and activation of macrophages in adipose tissue is the key modulator of the increase in contractility in arteries with perivascular fat following induction of inflammation. Despite multiple factors that may be involved in bringing about the vascular consequences of obesity, the ability of eplerenone to ameliorate the inflammatory effects of both aldosterone and hypoxia may be of potential therapeutic interest.

Traditional resuscitative practices fail to resolve metabolic acidosis in morbidly obese patients after severe blunt trauma

BACKGROUND

Obesity is a risk factor for postinjury complications; in particular, obese patients develop multiple organ failure (MOF) at a greater rate than do normal weight counterparts. Evaluation of differences in resuscitative practices altered by body mass index (BMI) might provide an explanation for the increased risk of MOF seen in these high-risk patients.

METHODS

We used prospectively collected multicenter data to retrospectively compare patients grouped by BMI with regard to resuscitation volumes and traditional end points during the first 48 hours after injury. Marshall MOF score was used as the primary outcome measure.

RESULTS

One thousand sixty-six patients were analyzed, with 877 meeting inclusion and exclusion criteria. All patients received similar volumes of resuscitation per kilogram lean and ideal body weight. Morbidly obese patients attained greater central venous pressures but otherwise differed little in attainment of standard cardiovascular end points. Despite this, morbidly obese patients resolved base deficit more slowly and remained in metabolic acidosis for 48 hours postinjury. Morbidly obese patients with persistent metabolic acidosis developed MOF at a significantly greater rate than did normal weight patients with or without persistent metabolic acidosis.

CONCLUSIONS

Morbidly obese trauma patients show prolonged metabolic acidosis despite receiving similar volumes and attaining similar end points of resuscitation when compared with patients in other BMI groups. Inadequate resuscitation based on inaccurate end points and metabolic disturbances associated with increased BMI are likely responsible; identification of the etiology, sources, and consequences of this acidosis may provide further insight into the susceptibility of the morbidly obese patient to develop postinjury organ failure.

Should prostate specific antigen be adjusted for body mass index? Data from the Baltimore Longitudinal Study of Aging

PURPOSE

Obesity may be associated with lower prostate specific antigen through hemodilution. We examined the relationship between body mass index and prostate specific antigen by age in men without prostate cancer in a longitudinal aging study to determine whether prostate specific antigen must be adjusted for body mass index.

MATERIALS AND METHODS

The study population included 994 men (4,937 observations) without prostate cancer in the Baltimore Longitudinal Study of Aging. Mixed effects models were used to examine the relationship between prostate specific antigen and body mass index in kg/m(2) by age. Separate models were explored in men with prostate cancer censored at diagnosis, for percent body fat measurements, for weight changes with time and adjusting for initial prostate size in 483 men (2,523 observations) with pelvic magnetic resonance imaging measurements.

RESULTS

In men without prostate cancer body mass index was not significantly associated with prostate specific antigen after adjusting for age (p = 0.06). A 10-point body mass index increase was associated with a prostate specific antigen difference of -0.03 ng/ml (95% CI -0.40-0.49). Results were similar when men with prostate cancer were included, when percent body fat was substituted for body mass index, and after adjusting for prostate volume. Longitudinal weight changes also had no significant association with prostate specific antigen.

CONCLUSIONS

Consistent with prior studies, we found an inverse relationship between obesity and serum prostate specific antigen. However, the magnitude of the difference was small. Thus, adjusting prostate specific antigen for body mass index does not appear warranted.

Tempol or candesartan prevents high-fat diet-induced hypertension and renal damage in spontaneously hypertensive rats

BACKGROUND

Obesity has been strongly associated with the development and aggravation of hypertension and chronic kidney disease. To date, the systemic renin-angiotensin system (RAS) has been known to involve in obesity-induced tissue damage and hypertension. However, the intrarenal mechanism whereby obesity induces and aggravates hypertension and renal disease remains poorly understood. Therefore, we investigated the role of intrarenal RAS and oxidative stress in diet-induced hypertension and renal inflammation in spontaneously hypertensive rats (SHR) fed a high-fat diet.

METHODS

Male SHR and Wistar-Kyoto rats (WKY) were divided into eight groups: normal-fat diet-fed WKY (WKY-NF), high-fat diet-fed WKY (WKY-HF), high-fat diet-fed tempol-treated WKY (WKY-HF/T), high-fat diet-fed candesartan-treated WKY (WKY-HF/C), normal-fat diet-fed SHR (SHR-NF), high-fat diet-fed SHR (SHR-HF), high-fat diet-fed tempol-treated SHR (SHR-HF/T) and high-fat diet-fed candesartan-treated SHR (SHR-HF/C). After 12 weeks of treatment, haemodynamic measurements and histological assessment of the kidney were performed.

RESULTS

At the end of week 12, the high-fat fed SHR gained more body weight, their systolic blood pressure was further elevated and glucose intolerance induced. There was no significant difference in the insulin resistance index, serum lipid profile, plasma renin activity and serum aldosterone levels according to diet. However, the high-fat diet resulted in increases in immunohistochemical stains of renin and angiotensin II in the kidney. The real-time PCR also demonstrated significant increases in mRNA levels of renin, angiotensinogen and angiotensin-converting enzyme in the kidney, reflecting enhanced activation of the intrarenal RAS, which findings were also shown by Western blot analysis for renin and angiotensin II type 1 receptor. The expression of ED-1, osteopontin and TGF-beta1 in the renal cortex were prominently enhanced in the SHR-HF group with the increased intrarenal lipid concentrations and oxidative stress. Administration of tempol or candesartan in the high-fat diet-induced SHR inhibited the elevation of the systolic blood pressure, intrarenal lipid concentrations, oxidative stress and the degree of renal inflammation to the levels of, or more than, the SHR-NF with no differences in the body weight and periepididymal fat weight, compared to those in the SHR-HF group without such treatment.

CONCLUSIONS

Our study suggests that a high-fat diet induces fatty kidneys, aggravation of blood pressure and renal inflammation in the SHR. Blockade of oxidative stress by tempol or of RAS by candesartan ameliorates the increase in blood pressure and renal inflammation and improves intrarenal lipid accumulation. Therefore, antioxidants or angiotensin receptor blockers can prevent diet-induced hypertension and renal inflammation in hypertensive rats.

Long-term weight loss from lifestyle intervention benefits blood pressure?: a systematic review

Weight gain may increase blood pressure. Weight loss may reduce this. Reviews have considered the long-term effects of weight loss but are related mainly to more obese participants often on obesity medication and/or undergoing obesity surgery. This systematic review, based on lifestyle interventions for adults (18 to 65 years) with mean baseline BMI of <35 kg/m(2), links weight change to blood pressure difference. A systematic review of studies reporting weight differences and blood pressure outcomes, published between 1990 and 2008 with follow-up of > or =2 years identified 8 clinical trials or controlled before and after studies (represented by 9 articles) and 8 cohort studies. Differences ranged from -11 to +4kg for weight, -7 to +2.2 mm Hg for diastolic blood pressure and -13 to +6.1 mm Hg for systolic blood pressure. For this population group, no quantifiable relationship between weight and diastolic blood pressure difference was found, possibly because of small weight losses, differing weight status responses, or because pharmacologically controlled hypertension masked weight loss influences. Systolic differences were in line with previous reviews of 1 kg:1 mm Hg relationship, but only for follow-up periods of 2 to 3 years, possibly reflecting the fact that regardless of maintained weight loss, blood pressure often reverts back to higher levels. Lifestyle interventions for weight and blood pressure are limited in this target group, and there has been no exploration of successful intervention components. An individual patient data analysis may uncover baseline and medication effects, explore differences between weight groups, and may identify successful components. Such an analysis would enable effective development of preventative interventions for both hypertension and obesity.

Salt-induced cardiac hypertrophy is independent of blood pressure and endothelin in obese, heart failure-prone SHHF rats

The interaction of salt sensitivity and obesity in development of cardiac hypertrophy is incompletely understood. The SHHF/Mcc-fa(cp) (SHHF) rat model was used to examine the effect of high salt on cardiac hypertrophy and expression of endothelin (ET) and nitric oxide synthase (NOS) isoforms. Homozygous lean (+/+) and obese (fa(cp)/fa(cp)) SHHF were fed a low-salt diet (0.3% NaCl) for seven days followed by a high-salt diet (8.0% NaCl) for seven days. To assess the role of ET in mediating cardiac hypertrophy and gene expression with high salt, additional groups were treated with an ET(A)/ET(B) receptor antagonist (bosentan) while on high salt. Obese SHHF showed an increase in systolic blood pressure and cardiac hypertrophy in response to the high-salt diet. High salt resulted in decreased expression of preproET as well as all three NOS isoforms in the Obese, while cytokine induced NOS (iNOS) and neuronal NOS (nNOS) increased in Leans. Though the salt-sensitive component of the hypertension observed in the Obese was prevented by bosentan, cardiac hypertrophy still occurred and expression of all NOS isoforms remained lower in Obese compared to Lean. Endothelial NOS (eNOS) expression increased in the Lean with bosentan. These studies suggest that cardiac hypertrophy is independent of the level of hypertension and may be mediated by altered production of NOS isoforms in salt-sensitive, obese SHHF.

Adrenocortical dysregulation as a major player in insulin resistance and onset of obesity

The aim of this review is to explore the dysregulation of adrenocortical secretions as a major contributor in the development of obesity and insulin resistance. Disturbance of adipose tissue physiology is one of the primary events in the development of pathologies associated with the metabolic syndrome, such as obesity and type 2 diabetes. Several studies indicate that alterations in metabolism of glucocorticoids (GC) and androgens, as well as aldosterone in excess, are involved in the emergence of metabolic syndrome. Cross talk among adipose tissue, the hypothalamo-pituitary complex, and adrenal gland activity plays a major role in the control of food intake, glucose metabolism, lipid storage, and energy balance. Perturbation of this cross talk induces alterations in the regulatory mechanisms of adrenocortical steroid synthesis, secretion, degradation, and/or recycling, at the level of the zonae glomerulosa (aldosterone), fasciculata (GC and GC metabolites), and reticularis (androgens and androgen precursors DHEA and DHEAS). As a whole, these adrenocortical perturbations contribute to the development of metabolic syndrome at both the paracrine and systemic level by favoring the physiological dysregulation of organs responsive to aldosterone, GC, and/or androgens, including adipose tissue.

Skinfold thickness and blood pressure across C-344T polymorphism of CYP11B2 gene

OBJECTIVE

To ascertain whether body adiposity is associated with the C-344T polymorphism of the CYP11B2 gene codifying for aldosterone synthase.

DESIGN

A cross-sectional epidemiological evaluation of a highly homogeneous unselected general population of Caucasians.

METHODS

Lifestyle, medical history, anthropometrics, subscapular, triceps and suprailiac skinfold thickness, lying blood pressure and biochemical measures were recorded in a population-based study among 1386 unselected subjects (56.5% women) living in a secluded valley. All were genotyped for C-344T allele status. Continuous variables were compared across genotypes with analysis of covariance and correlations evaluated using the Pearson method. Odds ratios (OR) were calculated for the TT and CT genotype versus the CC homozygotes and compared with the T-carriers with a logistic model.

RESULTS

The C-344T genotypic frequency did not deviate from Hardy-Weinberg equilibrium. In women, higher values of triceps and subscapular skinfold thickness were found in the CC homozygotes than in the T-carriers. In this sex, skinfold thickness also directly correlated with both systolic and diastolic blood pressure in the T-carriers only. The logistic regression for the dependent variable arterial hypertension showed an influence of triceps [OR 1.07, 95% confidence interval (CI) 1.02-1.12, P=0.006], subscapular (OR 1.13, 95% CI 1.06-1.20, P<0.0001) and suprailiac (OR 1.08, 95% CI 1.01-1.15, P=0.03) skinfold in T-carrier women only. These relationships were not detectable in men. The aldosterone-to-renin ratios were comparable across genotypes and sexes.

CONCLUSION

The C-344T polymorphism of the CYP11B2 gene seems to exert a sex-specific influence on body adiposity, independent of adrenal aldosterone.

DOCA stimulates salt appetite in Zucker rats: effect of dose, synergistic action with central angiotensin II, and obesity

An enhanced sodium appetite is found in rats by the synergist interaction of peripheral mineralocorticoids, deoxycorticosterone acetate (DOCA), and central angiotensin II (AngII), the synergy theory. We used obese Zucker rats which have a predisposition to develop hypertension under appropriate salt conditions to examine this synergy response between AngII and different low doses of DOCA on 2% NaCl intake. Obese and lean Zucker rats on low sodium food were treated systemically with 0.5, 1 and 2 mg/kg/day of DOCA for 3 days, before receiving i.c.v. AngII (10 pmol) on the fourth day. Food, fluid intakes and urine outputs were measured daily throughout. Plasma aldosterone levels were also analysed. Results showed that AngII alone increased water but not salt intake, whereas all three doses of DOCA by themselves enhanced daily salt intake during the treatment period. The lowest dose of DOCA plus AngII did not stimulate an enhanced sodium consumption. The 1 mg/kg was the threshold dose of DOCA for a synergistic response, and with 2 mg/kg DOCA the obese rats consumed nearly 2-fold more hypertonic NaCl solution than the leans. Moreover, obese baseline plasma levels of aldosterone were more elevated than the lean rats. In conclusion, in adult Zucker rats a threshold level of mineralocorticoid is required for the salt stimulating action of central AngII. In the obese rat the synergistic effect is enhanced with higher doses of mineralocorticoid, suggesting that the plasma level of aldosterone could be a prominent factor, which may predispose the obese to salt-sensitivity and, possibly, subsequently to hypertension under appropriate conditions.

Obesity cardiomyopathy: pathogenesis and pathophysiology

Obesity is becoming a worldwide phenomenon. Myocardial changes associated with the obese state are increasingly recognized, independent of hypertension, obstructive sleep apnea and coronary artery disease. The existence of a cardiomyopathy of obesity is supported by a range of evidence: epidemiologic study findings, which have shown an association between obesity and heart failure; clinical studies that have confirmed the association of adiposity with left ventricular dysfunction, independent of hypertension, coronary artery disease and other heart disease; and experimental evidence of structural and functional changes in the myocardium in response to increased adiposity. The most important mechanisms in the development of obesity cardiomyopathy are metabolic disturbances (insulin resistance, increased free fatty acid levels, and also increased levels of adipokines), activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, myocardial remodeling, and small-vessel disease (both microangiopathy and endothelial dysfunction). In the first part of this two-part Review, we seek to evaluate the emerging evidence for the existence of a cardiomyopathy of obesity and clarify the responsible mechanisms.

Improvement of chronic heart failure by dexamethasone is not associated with downregulation of leptin in rats

AIM

To demonstrate the hypothesis that dexamethasone (Dex) could improve chronic heart failure (CHF) by inhibiting the downstream signaling transduction of leptin but had no influence on the upregulation of leptin and its receptor in myocardium.

METHODS

CHF was induced by left coronary artery ligation for 6 weeks. CHF rats were treated with Dex 50 mg.kg/d. Hemodynamics, histology, reactive oxygen species (ROS)-related parameters, and leptin concentrations in serum were measured. The mRNA expression of matrix metalloproteinases (MMP)2/9, tissue inhibitor of metalloproteinases (TIMP)1/2, tumor necrosis factor (TNF)-alpha, and OB-Rb were measured by RT-PCR.

RESULTS

In the CHF rats, hemodynamic functions were deteriorated, which was accompanied with myocardium remodeling and histological changes. CHF rats showed hyperleptinemia and excessive ROS in the serum, and the upregulation of MMP-2/9, TNF-alpha, and leptin receptor mRNA and downregulation of TIMP-1/2 mRNA in the myocardium compared with the sham operation group. Dex treatment significantly ameliorated CHF in association with the reversion of the abnormalities of MMP-2/9, TIMP-1/2, TNF-alpha, and ROS. But Dex had no influence on the hyperleptinemia and the upregulated leptin and its receptor in the myocardium during CHF.

CONCLUSION

Dex improves CHF by inhibiting TNF-alpha, MMP-2, MMP-9, and ROS. Dex had no effects on upregulated leptin and its receptor expression and hyperleptinemia induced by CHF.

Fat tissue metabolism and adrenal steroid secretion

Obesity has reached epidemic proportions in Western societies, contributing to metabolic diseases, hypertension, and vascular diseases. White adipose tissue has traditionally been regarded merely as lipid, and consequently, as energy storage. However, recent data revealed the importance of adipose tissue as a highly active endocrine organ and its involvement in the body's metabolism and homeostasis. Obesity is associated with several endocrine disorders, including adrenocortical malfunction. Because of the central role of adrenal function in the body's homeostasis, adrenal malfunction is important in the development of other obesity-related abnormalities. Therefore, in this short review, we summarize recent data on obesity-induced changes in adrenocortical mineralocorticoid, glucocorticoid, and androgen secretions and their consequences for metabolism.

Mineralocorticoid-stimulating activity of adipose tissue

Obesity is strongly associated with arterial hypertension. A positive correlation between obesity and plasma aldosterone levels has been observed by different investigators, suggesting that an abnormal secretion of aldosterone in obesity contributes to the development of arterial hypertension in obese subjects. The mechanisms proposed to explain this abnormal aldosterone production mainly involve the adipose renin-angiotensin system, an indirect effect of increased fatty acids, and direct adrenal stimulation by adipocyte secretory products. Indeed, adipose mineralocorticoid-stimulating activity was recently observed in isolated human adipocytes, suggesting a hitherto unknown direct involvement of adipose tissue in the regulation of blood pressure in obesity.

Hypertension and the Metabolic Syndrome

The cause of hypertension in the metabolic syndrome is complex and multifactorial and all of the elements of the metabolic syndrome, including obesity, insulin resistance, and the characteristic dyslipidemia probably are involved in mediating changes ultimately resulting in hypertension and modifying its course. Of these elements, obesity may play the most important and pivotal role in creating the conditions that lead to hypertension in the metabolic syndrome. This is not to say that the other elements of the syndrome are less important, and, as we gain more insight into the processes involved, we should be able to better manage the disease and tailor our therapeutic interventions appropriately.

Diet-induced obesity delays cardiovascular recovery from stress in spontaneously hypertensive rats

OBJECTIVE

Blood pressure (BP) and heart rate (HR) responses to stress are significant predictors of cardiovascular morbidity and mortality. Because obesity is a major risk factor for cardiovascular disease, we examined whether diet-induced obesity alters the BP and HR responses to stress and whether these alterations are associated with augmented cardiovascular morbidity in the rat.

RESEARCH METHODS AND PROCEDURES

Adult male spontaneously hypertensive rats were fed either a normal diet or high-fat diet (HFD) for 12 weeks. At weeks 0 and 12, body weight was measured, and BP and HR were recorded by radiotelemetry throughout three consecutive day and night periods and in response to 30-minute immobilization stress. At the end of the 12-week intervention, the rats were sacrificed, and their organs and sera were collected.

RESULTS

With the intervention, HFD rats showed a significantly greater increase in body weight (as expected) and circulating leptin and free fatty acid levels compared with normal diet rats. In addition, they showed similar increases in BP and HR elevations during stress but significantly slower BP and HR decreases after stress. These HFD-induced delays in stress recovery were associated with BP and HR elevations during the night (behaviorally active) period and with augmentations in cardiac mass.

DISCUSSION

The results of this study indicate that, in spontaneously hypertensive rats, dietary obesity delays cardiovascular recovery from stress, and, in parallel, it promotes the development of nocturnal hypertension as well as cardiac hypertrophy. This suggests that dietary obesity may significantly potentiate the impact of daily stressful experiences on the cardiovascular system.

Method for coronary angiography in morbidly obese patients

Cardiac catheterization in morbidly obese patients is difficult. In addition to problems regarding vascular access and radiographic penetration of the chest, the engineering parameters and physical limitations of the table and its supporting structures may limit these patients' ability to undergo clinically indicated coronary angiography. We describe a method for cardiac catheterization in which much of the obese patient's body weight is supported on a stretcher placed at right angles to the catheterization table, with only the thorax on the table under the image intensifier. Using this method, five consecutive successful diagnostic procedures and one coronary stent procedure have been performed without complication. Limitations of this procedure include inability to achieve the normal variety of angiographic views due to constraints on image intensifier rotation and skew.

Efeitos da suplementação de potássio via sal de cozinha sobre a pressão arterial e a resistência à insulina em pacientes obesos hipertensos em uso de diuréticos

OBJETIVO: Avaliar os efeitos da suplementação de potássio, por intermédio do sal de cozinha contendo cloreto de potássio, associada à dieta hipocalórica e à atividade física aeróbica, sobre a pressão arterial e índices de resistência à insulina em pacientes hipertensos com obesidade abdominal. MÉTODOS: Estudo prospectivo duplo-cego, randomizado, em 22 pacientes hipertensos com excesso de peso (índice de massa corporal >27kg/m²) e controle insatisfatório da pressão arterial durante o uso de diuréticos pressão arterial sistólica >140 e <160mmHg e/ou pressão arterial diastólica >90 e <105mmHg. O estudo teve duração de 12 semanas, durante as quais, os pacientes, divididos em dois grupos (grupo sal normal, n=10; grupo sal de potássio, n=12), receberam sal contendo 100% de cloreto de sódio, ou sal contendo 50% de cloreto de sódio e 50% de cloreto de potássio. No início e ao final do estudo, os pacientes foram submetidos à determinação do índice de massa corporal, da circunferência da cintura, dos níveis séricos e da excreção urinária de sódio e potássio, à monitorização ambulatorial da pressão arterial nas 24 horas, ao teste oral de tolerância à glicose com determinação dos níveis séricos de insulina em jejum e aos 120 minutos, à determinação do perfil lipídico do plasma e à medida da composição corporal. RESULTADOS: No grupo sal de potássio, os níveis do potássio sérico não se elevaram, como no grupo sal normal, embora se elevasse de 38,8±18,6 para 62,3±29,7mEq/g a excreção de creatinina urinária (p<0,05). A perda de peso, semelhante nos dois grupos (3,5% no grupo sal normal e 2,7% no grupo sal de potássio), associou-se às reduções na pressão arterial sistólica durante a monitorização ambulatorial da pressão arterial; de 134,7 ±14,8 para 130,2±12,6mmHg (p<0,05) no grupo sal normal e de 128,2±7,4 para 122,9±5,7mmHg (p<0,05) no grupo sal de potássio, e às reduções na pressão arterial diastólica durante a monitorização ambulatorial da pressão arterial, de 84,4±10,2 para 81,4 ± 8,9mmHg no grupo sal normal e de 84,0±5,7 para 79,5±3,9mmHg (p<0,05) no grupo sal de potássio. As variações da pressão arterial sistólica, semelhantes nos dois grupos, correlacionaram-se com as variações das medidas da circunferência da cintura em todos os pacientes analisados em conjunto (r s=0,624; p=0,002). Os índices de resistência à insulina e o perfil lipídico do plasma não se alteraram e não diferiram entre os grupos. CONCLUSÃO: Nossos resultados indicam que as perdas de peso induzidas por alterações no estilo de vida promovem reduções na pressão arterial, proporcionais às reduções na gordura abdominal. A suplementação de potássio a partir da utilização do sal de cozinha contendo cloreto de potássio, em pacientes hipertensos obesos em uso de diurético, se mostrou insuficiente para impedir a queda dos níveis séricos de potássio e não resultou em nenhum efeito sobre a resistência à insulina ou sobre a pressão arterial, além daquele obtido pela perda de peso.

N-Terminal Pro-B-Type Natriuretic Peptide as an Indicator of Possible Cardiovascular Disease in Severely Obese Individuals: Comparison with Patients in Different Stages of Heart Failure

Background: Mild stages of heart failure might be difficult to diagnose in severely obese individuals with a body mass index (BMI) &gt;40 kg/m2. Measurement of the N-terminal fragment of pro-B-type natriuretic peptide (NT-proBNP) is feasible for detecting cardiac impairment. The aims of our study were to measure NT-proBNP in plasma of severely obese patients and to compare the results with results for patients in different stages of manifest cardiac dysfunction.

Methods: In 61 severely obese individuals (median BMI, 43.2 kg/m2) and 96 nonobese patients with existing heart failure [classified into New York Heart Association (NYHA) classes I–IV], NT-proBNP was measured in the fasting condition. A medical history, physical examination, electrocardiography, blood chemistry, and chest x-ray were performed in the obese group. In addition, echocardiography was performed in the NYHA group.

Results: In obese individuals, NT-proBNP was increased to a median of 356 (interquartile range, 221–458) pmol/L [854 (530–1099) ng/L] and was comparable (P &gt;0.05) to the median value for NYHA I patients {289 (258–451) pmol/L [694 (619–1082) ng/L]}, but was significantly lower than in the other NYHA groups (P &lt;0.001 for each).

Conclusion: The prognostic relevance of increased NT-proBNP for risk of developing cardiac insufficiency in severely obese patients needs to be further evaluated.

Fat cells may be the obesity-hypertension link: human adipogenic factors stimulate aldosterone secretion from adrenocortical cells

Obesity has become an epidemic problem in Western societies contributing to several disease processes including metabolic diseases, hypertension, and cardiovascular disease. Overweight and obesity are frequently associated with increased plasma levels of aldosterone suggesting a direct link between obesity hypertension and increased mineralocorticoid levels. The adipocyte has long been suggested to be directly involved in the regulation of the body's homeostasis and recent evidence now proves that human fat is a highly active endocrine tissue. We therefore tested the hypothesis that adipocyte secretory products directly stimulate adrenocortical aldosterone secretion. Indeed, secretory products from isolated human adipocytes strongly stimulated steroidogenesis in human adrenocortical cells (NCI-H295R), as well as in bovine adrenocortical cells with a predominant effect on mineralocorticoid secretion. In conclusion, a possible direct link exists between fat tissue metabolism and adrenal mineralocorticoid secretion that may be responsible for obesity-related hypertension.

Associations of short-term weight changes and weight cycling with incidence of essential hypertension in the EPIC-Potsdam Study

The aim of this study was to examine the relationships of short-term weight gain, weight loss, and weight cycling on the odds of developing hypertension. Normotensive middle-aged German men and women (n=12,362) of the European Prospective Investigation into Cancer and Nutrition-Potsdam Study were assigned to categories of 2-year short-term weight changes that were self-reported to have occurred prior to recruitment into the study (gain only, loss only, weight cycling, stable). After 2 years of follow-up after recruitment, 180 cases of incident essential hypertension were identified. In logistic regression models, odds ratios were estimated for the associations between short-term weight changes and risk of developing hypertension. Obesity status (BMI>or=30 or BMI<30 kg/m2) modified the associations between short-term weight change and incidence of diagnosed hypertension. Among obese individuals, short-term weight gain occurring during the 2 years prior to recruitment (OR=2.79, 95% CI 1.19-6.56), weight loss (OR=6.74, 95% CI 2.58-17.6) and weight cycling (OR=4.29, 95% CI 1.55-11.9) were strongly positively associated with incident hypertension, adjusted for age and gender, compared to obese individuals with short-term stable weight. No significant associations between short-term weight changes and risk of diagnosed hypertension were detected among non-obese individuals. Short-term weight changes appeared to present strong risk factors for developing hypertension among obese individuals. The effect seen for weight cycling supports the hypothesis that weight cycling increases the risk of hypertension. The finding for short-term weight loss may be explained by subsequent weight regain and needs further investigation.

Lifestyle and dietary modification for prevention of heart failure

This article discusses the factors that contribute most to systolic and diastolic heart failure (HF): ischemic heart disease, hypertension,obesity, diabetes, and nephropathy. Diabetes often follows the insulin resistance syndrome in which obesity and hypertension are combined with dyslipidemia, and obesity is likely causal. Diabetes and hypertension are common causes of nephropathy, which in turn is a common precursor to HF. Insulin resistance, obesity,dyslipidemia, diabetes, and hypertension are risk factors for atherosclerotic coronary disease and left ventricular ischemia. Each is also a risk factor for diastolic dysfunction.

Association between ghrelin and cardiovascular indexes in healthy obese and lean men

OBJECTIVE

Obesity is an increasingly common condition and is associated with excess morbidity and mortality, including clinical and subclinical cardiac dysfunction. The role of hormones involved in energy homeostasis, including ghrelin and leptin, in cardiovascular function remains incompletely understood. Therefore, we sought to evaluate the association between systemic ghrelin and leptin levels with indexes of cardiovascular structure and function.

DESIGN AND MEASUREMENTS

We measured serum ghrelin and leptin levels in 25 clinically healthy obese men and 25 lean controls, using commercially available immunoassays. We also assessed right and left ventricular structure and function using cardiac magnetic resonance imaging. We then investigated the association between serum ghrelin and leptin levels with cardiac indexes, using univariate and multivariate analysis.

RESULTS

There was an independent association between serum ghrelin levels and height-adjusted right ventricular mass (r = -0.324, P = 0.026), right ventricular end-diastolic volume (r = -0.363, P = 0.017) and right ventricular end-systolic volume (r = -0.398, P = 0.009) as well as right ventricular ejection fraction (r = 0.317, P = 0.050). There was no significant association between serum ghrelin and indexes of left ventricular structure or function. We also identified an association between serum leptin levels and resting heart rate (r = 0.391, P = 0.002). There was an association between serum leptin and height-adjusted left ventricular mass on univariate, but not on multivariate, analysis.

CONCLUSIONS

Serum ghrelin is associated with right ventricular cardiovascular indexes and serum leptin is associated with resting heart rate. These associations indicate a close interaction between the endocrine and cardiovascular systems in obesity.

Human adipocytes secrete mineralocorticoid-releasing factors

Obesity has become an epidemic problem in western societies, contributing to metabolic diseases, hypertension, and cardiovascular disease. Overweight and obesity are frequently associated with increased plasma levels of aldosterone. Recent evidence suggests that human fat is a highly active endocrine tissue. Therefore, we tested the hypothesis that adipocyte secretory products directly stimulate adrenocortical aldosterone secretion. Secretory products from isolated human adipocytes strongly stimulated steroidogenesis in human adrenocortical cells (NCI-H295R) with a predominant effect on mineralocorticoid secretion. Aldosterone secretion increased 7-fold during 24 h of incubation. This stimulation was comparable to maximal stimulation of these cells with forskolin (2 x 10(-5) M). On the molecular level, there was a 10-fold increase in the expression of steroid acute regulatory peptide mRNA. This effect was independent of adipose angiotensin II as revealed by the stimulatory effect of fat cell-conditioned medium even in the presence of the angiotensin type 1 receptor antagonist, valsartan. None of the recently defined adipocytokines accounted for the effect. Mineralocorticoid-stimulating activity was heat sensitive and could be blunted by heating fat cell-conditioned medium to 99 degrees C. Centrifugal filtration based on molecular mass revealed at least two releasing factors: a heat sensitive fraction (molecular mass >50 kDa) representing 60% of total activity, and an inactive fraction (molecular mass <50 kDa). However, the recovery rate increased to 92% when combining these two fractions, indicating the interaction of at least two factors. In conclusion, human adipocytes secrete potent mineralocorticoid-releasing factors, suggesting a direct link between obesity and hypertension.

Obesity and Heart Failure

Current statistics on global obesity are staggering. In 2002, the International Obesity Task Force estimated that worldwide, nearly 1 billion (6%) people were overweight or obese. The American Heart Association's 2002: "Top 10" Research Advances for the Treatment of Heart Disease include obesity as a strong and independent risk factor for developing heart failure. This article outlines national and world statistics, cardiac risk factors, and pathophysiologic theories outlining the cellular mechanisms that associate obesity and heart failure. Access to guidelines for effective screening, evaluation, and treatment of obesity are also provided.

Nutritional factors in the control of blood pressure and hypertension

Differing hypertension prevalence rates between certain population and age groups are partially due to differences in the intake of certain nutrients. Blood pressure is positively associated with higher sodium, alcohol, and protein intakes; it is inversely associated with potassium, calcium, and magnesium intakes. Salt may lead to an increase in blood pressure in the presence of salt sensitivity, but there is no inexpensive or easy strategy to identify salt-sensitive patients. Other risk factors for hypertension include obesity and lack of regular physical activity. The best strategy appears to be moderate salt restriction (6-7 g/day) in combination with an optimal compliance of the antihypertensive drug therapy, as well as adoption of the combination diet of the DASH study--a diet rich in fruits and vegetables, and thus rich in potassium. Current evidence does not support the increased intake of Ca2+ or Mg2+ for blood-pressure-lowering purposes only; however, calcium and magnesium may represent important components in the combination diet of the DASH study. It seems that it is the combination of these nutrients that is of crucial importance for the achievement of optimal blood-pressure reduction. Also recommended is a decrease in alcohol consumption and an increase in regular physical activity. Instead of a severe intervention with regard to 1 risk factor alone, positive changes in 5 habits combined--high salt intake, high sodium-to-potassium ratio, alcohol intake, calorie imbalance, and a sedentary life--may be the most realistic and effective strategy to counteract the present hypertension epidemic.