Effects of Aerobic Exercise Training on Cardiac Renin-Angiotensin System in an Obese Zucker Rat Strain

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Abstract

Objective

Obesity and renin angiotensin system (RAS) hyperactivity are profoundly involved in cardiovascular diseases, however aerobic exercise training (EXT) can prevent obesity and cardiac RAS activation. The study hypothesis was to investigate whether obesity and its association with EXT alter the systemic and cardiac RAS components in an obese Zucker rat strain.

Methods

The rats were divided into the following groups: Lean Zucker rats (LZR); lean Zucker rats plus EXT (LZR+EXT); obese Zucker rats (OZR) and obese Zucker rats plus EXT (OZR+EXT). EXT consisted of 10 weeks of 60-min swimming sessions, 5 days/week. At the end of the training protocol heart rate (HR), systolic blood pressure (SBP), cardiac hypertrophy (CH) and function, local and systemic components of RAS were evaluated. Also, systemic glucose, triglycerides, total cholesterol and its LDL and HDL fractions were measured.

Results

The resting HR decreased (∼12%) for both LZR+EXT and OZR+EXT. However, only the LZR+EXT reached significance (p<0.05), while a tendency was found for OZR versus OZR+EXT (p = 0.07). In addition, exercise reduced (57%) triglycerides and (61%) LDL in the OZR+EXT. The systemic angiotensin I-converting enzyme (ACE) activity did not differ regardless of obesity and EXT, however, the OZR and OZR+EXT showed (66%) and (42%), respectively, less angiotensin II (Ang II) plasma concentration when compared with LZR. Furthermore, the results showed that EXT in the OZR prevented increase in CH, cardiac ACE activity, Ang II and AT2 receptor caused by obesity. In addition, exercise augmented cardiac ACE2 in both training groups.

Conclusion

Despite the unchanged ACE and lower systemic Ang II levels in obesity, the cardiac RAS was increased in OZR and EXT in obese Zucker rats reduced some of the cardiac RAS components and prevented obesity-related CH. These results show that EXT prevented the heart RAS hyperactivity and cardiac maladaptive morphological alterations in obese Zucker rats.

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Most cited references 36

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Cardiac remodeling in obesity.

E. Dale Abel, Sheldon Litwin, Gary Sweeney (2008)

The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic.

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Relationship of baseline serum cholesterol levels in 3 large cohorts of younger men to long-term coronary, cardiovascular, and all-cause mortality and to longevity.

Jeremiah Stamler (2000)

Based on observational and interventional data for middle-aged cohorts (aged 40-64 years), serum cholesterol level is known to be an established major risk factor for coronary heart disease (CHD). However, findings for younger people are limited, and the value of detecting and treating hypercholesterolemia in younger adults is debated. To evaluate the long-term impact of unfavorable serum cholesterol levels on risk of death from CHD, cardiovascular disease (CVD), and all causes. Three prospective studies, from which were selected 3 cohorts of younger men with baseline serum cholesterol level measurements and no history of diabetes mellitus or myocardial infarction. A total of 11,017 men aged 18 through 39 years screened in 1967-1973 for the Chicago Heart Association Detection Project in Industry (CHA); 1266 men aged 25 through 39 years examined in 1959-1963 in the Peoples Gas Company Study (PG); and 69,205 men aged 35 through 39 years screened in 1973-1975 for the Multiple Risk Factor Intervention Trial (MRFIT). Cause-specific mortality during 25 (CHA), 34 (PG), and 16 (MRFIT) years of follow-up; mortality risks; and estimated life expectancy in relation to baseline serum cholesterol levels. Death due to CHD accounted for 26%, 34%, and 28% of all deaths in the CHA, PG, and MRFIT cohorts, respectively; and CVD death for 34%, 42%, and 39% of deaths in the same cohorts, respectively. Men in all 3 cohorts with unfavorable serum cholesterol levels (200-239 mg/dL [5.17-6.18 mmol/L] and >/=240 mg/dL [>/=6.21 mmol/L]) had strong gradients of relative mortality risk. For men with serum cholesterol levels of 240 mg/dL or greater (>/=6.21 mmol/L) vs favorable levels (<200 mg/dL [<5.17 mmol/L]), CHD mortality risk was 2.15 to 3.63 times greater; CVD disease mortality risk was 2.10 to 2.87 times greater; and all-cause mortality was 1.31 to 1.49 times greater. Hypercholesterolemic men had age-adjusted absolute risk of CHD death of 59 per 1000 men in 25 years (CHA cohort), 90 per 1000 men in 34 years (PG cohort), and 15 per 1000 men in 16 years (MRFIT cohort). Absolute excess risk was 43.6 per 1000 men (CHA), 81.4 per 1000 men (PG), and 12.1 per 1000 men (MRFIT). Men with favorable baseline serum cholesterol levels had an estimated greater life expectancy of 3.8 to 8.7 years. These results demonstrate a continuous, graded relationship of serum cholesterol level to long-term risk of CHD, CVD, and all-cause mortality, substantial absolute risk and absolute excess risk of CHD and CVD death for younger men with elevated serum cholesterol levels, and longer estimated life expectancy for younger men with favorable serum cholesterol levels. JAMA. 2000;284:311-318

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Weight loss and the renin-angiotensin-aldosterone system.

Stefan Engeli, Jana Böhnke, Kerstin Gorzelniak … (2005)

The renin-angiotensin-aldosterone system has been causally implicated in obesity-associated hypertension. We studied the influence of obesity and weight reduction on the circulating and adipose tissue renin-angiotensin-aldosterone system in menopausal women. Blood samples were analyzed for angiotensinogen, renin, aldosterone, angiotensin-converting enzyme activity, and angiotensin II. In adipose tissue biopsy samples, we analyzed angiotensinogen, renin, renin-receptor, angiotensin-converting enzyme, and angiotensin II type-1 receptor gene expression. Obese women (n=19) had higher circulating angiotensinogen, renin, aldosterone, and angiotensin-converting enzyme than lean women (n=19), and lower angiotensinogen gene expression in adipose tissue. Seventeen women successfully participated in a weight reduction protocol over 13 weeks to reduce daily caloric intake by 600 kcal. Body weight was reduced by -5%, as were angiotensinogen levels by -27%, renin by -43%, aldosterone by -31%, angiotensin-converting enzyme activity by -12%, and angiotensinogen expression by -20% in adipose tissue (all P<0.05). The plasma angiotensinogen decrease was highly correlated with the waist circumference decline (r=0.74; P<0.001). Weight and renin-angiotensin-aldosterone system reductions were accompanied by a -7-mm Hg reduced systolic ambulatory blood pressure. These data suggest that a 5% reduction in body weight can lead to a meaningfully reduced renin-angiotensin-aldosterone system in plasma and adipose tissue, which may contribute to the reduced blood pressure.

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Author and article information

Contributors

Reury F. P. Bacurau: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2012

Publication date (Electronic): 12 October 2012

Volume: 7

Issue: 10

Electronic Location Identifier: e46114

Affiliations

[1 ]Laboratory of Biochemistry and Molecular Biology of Exercise, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil

[2 ]Experimental Physiopathology, University of São Paulo, Medical School, São Paulo, Brazil

[3 ]Heart Institute (InCor), University of São Paulo, Medical School, São Paulo, Brazil

University of Sao Paulo, Brazil

Author notes

* E-mail: edilamar@ 123456usp.br

Competing Interests: The authors have declared that no competing interests exist.

Conceived and designed the experiments: EMO CEN. Performed the experiments: DLMB FCM TF ECDC. Analyzed the data: DLMB EMO. Contributed reagents/materials/analysis tools: MCI KTR. Wrote the paper: DLMB EMO FCM.

Article

Publisher ID: PONE-D-12-00246

DOI: 10.1371/journal.pone.0046114

PMC ID: 3470582

PubMed ID: 23077501

SO-VID: aa396793-18c9-46a5-b2ec-0ca3e52c5125

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 15 December 2011

Date accepted : 28 August 2012

Page count

Pages: 10

Funding

The present investigation was supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico (MCT/CNPq 485720/07-8). D.L.M. Barretti and T. Fernandes were the recipients of fellowships from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, No. 07/52458-0 and 07/56771-4). E.M. Oliveira was awarded scholarships from CNPq (No. 307591/2009-3), Brazil. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Effects of Aerobic Exercise Training on Cardiac Renin-Angiotensin System in an Obese Zucker Rat Strain

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Abstract

Objective

Methods

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Conclusion

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PLOS Climate

Most cited references 36

Cardiac remodeling in obesity.

Relationship of baseline serum cholesterol levels in 3 large cohorts of younger men to long-term coronary, cardiovascular, and all-cause mortality and to longevity.

Weight loss and the renin-angiotensin-aldosterone system.

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