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In pathological cardiac hypertrophy, the heart is more dependent on glucose than fatty acids. This shift in energy metabolism occurs due to several factors, including the oxygen deficit, which activates hypoxia-inducible factor-1α (HIF-1α), a critical molecule related to glucose metabolism. However, there are gaps regarding the behavior of key proteins in the glycolytic pathway and HIF-1α during the transition from hypertrophy to heart failure (HF). This study assesses the hypothesis that there is an early change and enhancement of HIF-1α and the glycolytic pathway, as well as an association between them during cardiac remodeling. Sham and aortic stenosis Wistar rats were analyzed at 2, 6, and 18 weeks and in HF (n = 10–18). Cardiac structure and function were investigated by echocardiogram. Myocardial glycolysis, the aerobic and anaerobic pathways and glycogen were analyzed by enzymatic assay, Western blot, and enzyme-linked immunosorbent assay (ELISA). The following were observed: increased left ventricular hypertrophy; early diastolic function change and severe systolic and diastolic dysfunction in HF; increased HIF-1α in the 2nd week and in HF; precocious alteration and intensification of glycolysis with a shift to anaerobic metabolism from the 6th week onwards; association between HIF-1α, glycolysis, and the anaerobic pathway. Our hypothesis was confirmed as there was an early change and intensification in glucose metabolism, alteration in HIF-1α, and an association between data during the progression from hypertrophy to heart failure.

Resumo Fundamento A obesidade é um fator de risco para complicações médicas, incluindo o sistema cardiovascular. Há informações limitadas sobre o colágeno no coração obeso. Nosso estudo anterior demonstrou uma redução dos níveis proteicos de colágeno miocárdico tipo I em ratos obesos alimentados com uma dieta com alto teor de gordura durante 34 semanas. No entanto, os mecanismos responsáveis pelos níveis baixos não estão completamente elucidados. Objetivo O objetivo deste estudo foi testar a hipótese de que a redução do colágeno tipo I está associada ao aumento da atividade da metaloproteinase-2 (MMP-2), a qual está ligada à elevação de leptina no miocárdio de ratos obesos. Métodos Ratos Wistar machos com 30 dias de idade foram randomizados em dois grupos: controle (dieta padrão) e obeso (dieta com alto teor de gordura), e alimentados durante 34 semanas. Foram avaliados as características gerais dos animais e os perfis metabólicos e endócrinos. Foram avaliados as expressões proteicas miocárdicas de colágeno tipo I, leptina e inibidores teciduais de metaloproteinases (TIMP), bem como a atividade da MMP-2. O teste de correlação de Pearson foi aplicado para determinar as associações entre variáveis. O nível de significância foi de 5%. Resultados Os animais obesos apresentaram índice de adiposidade mais elevado em comparação ao controle. Foram observadas comorbidades como intolerância à glicose, hiperinsulinemia, resistência à insulina, hiperleptinemia e hipertensão nos ratos obesos. A obesidade reduziu o colágeno tipo I, TIMP-1 e TIMP-2, e aumentou a leptina e a MMP-2 no miocárdio. Houve uma correlação negativa entre o colágeno tipo I e a MMP-2 e uma correlação positiva entre a leptina e a MMP-2. Conclusão Foi confirmada a hipótese de que a redução do colágeno tipo I está associada ao aumento da atividade da MMP-2 e da expressão de leptina no miocárdio de ratos obesos. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0) Abstract Background Obesity is a risk factor for medical complications, including the cardiovascular system. There is limited information on collagen in the heart in obesity. Our previous study showed decreased protein levels of myocardial collagen type I in obese rats fed a high-fat diet for 34 weeks. However, the mechanisms responsible for low levels are not fully elucidated. Objective The purpose of this study was to test the hypothesis that the reduction in collagen type I is associated with increased metalloproteinase-2 (MMP-2) activity, which is linked to elevated leptin in the myocardium of obese rats. Methods Thirty-day-old male Wistar rats were randomized into two groups, control (standard diet) and obese (high-fat diet), and fed for 34 weeks. The general animal characteristics and metabolic and endocrine profiles were evaluated. Myocardial protein expressions of collagen I, leptin, tissue inhibitors of metalloproteinases (TIMP), and MMP-2 activity were assessed. Pearson correlation was employed to determine the associations between variables. The level of significance was 5%. Results The obese animals had increased adiposity index compared to control. Comorbidities such as glucose intolerance, hyperinsulinemia, insulin resistance, hyperleptinemia, and hypertension were observed in obese rats. Obesity reduced collagen I, TIMP-1, and TIMP-2, and it increased leptin and MMP-2 in the myocardium. There was a negative correlation between collagen I and MMP-2 and a positive correlation between leptin and MMP-2. Conclusion The hypothesis was confirmed; the reduction in collagen type I is associated with increased MMP-2 activity and leptin expression in the myocardium of obese rats. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)

Made available in DSpace on 2020-12-12T02:05:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) It has been described that the cardiac dysfunction in the obesity model is because of collagen imbalance and that angiotensin II (Ang II) contributes to myocardial fibrosis. However, it remains undefined if changes in collagen I and III metabolism in obesity is due to the renin-angiotensin system (RAS) dysregulation from myocardium or excessive adipose tissue. Aim: This study aimed to verify whether the changes in myocardial collagen metabolism result from RAS deregulation of cardiac or adipose tissue in an obesity model. Main methods: Wistar rats were fed with control (CD) and high-fat (HFD) diets for 30 weeks. After the dietary intervention, animals were assigned to be treated with losartan at the 30 mg/kg/day dosage or kept untreated for an additional five weeks. Key findings: HFD induced obesity, comorbidities, and cardiac collagen overexpression. The HFD group presented an increase in Ang II levels in both adipose tissue and plasma, as well as AT1 receptor expression in cardiac tissue. Of note, the myocardial Ang II was not changed in the HFD group. Losartan administration reduced some obesity-induced comorbidities regardless of weight loss. The AT1 receptor blockade also decreased the release of Ang II from adipose tissue and myocardial AT1 receptor and collagen. Significance: It was seen that excessive adipose tissue is responsible for the exacerbated circulating Ang II, which induced cardiac fibrosis development. Department of Internal Medicine Botucatu Medical School São Paulo State University (UNESP), Botucatu Department of Morphology Institute of Biosciences São Paulo State University (UNESP), Botucatu Department of Pathology Botucatu Medical School São Paulo State University (UNESP), Botucatu Department of Biostatistics Institute of Biosciences São Paulo State University (UNESP), Botucatu Laboratory of Biochemistry and Molecular Biology of the Exercise School of Physical Education and Sport University of São Paulo (USP) Department of Internal Medicine Botucatu Medical School São Paulo State University (UNESP), Botucatu Department of Morphology Institute of Biosciences São Paulo State University (UNESP), Botucatu Department of Pathology Botucatu Medical School São Paulo State University (UNESP), Botucatu Department of Biostatistics Institute of Biosciences São Paulo State University (UNESP), Botucatu

High fat diets (HFDs) are used frequently to study the development of cardiac dysfunction in animal models of obesity and diabetes. However, impairment in systolic function, often reported as declining ejection fraction, may not consistently occur in a given time frame which could be contributable to a variety of factors within the experimental design. One major factor may be the amounts of saturated and unsaturated fatty acids (FAs) that are present in the diet. To determine whether the FA content and composition was a critical determinant in the development of cardiac dysfunction in response to high fat feeding, we fed adult, male mice either Western diet (WD, 45% fat, 60% saturated), Surwit diet (SD, 60% fat, 90% saturated), milk-fat based diet (MFBD, 60% fat, 60% saturated), or high fat Western diet (HFWD, 60% fat, 32% saturated) for 12 weeks. We report that neither the amount of total fat nor the ratio of saturated to unsaturated FAs in the diets differentially affect body weight and adiposity in mice. In addition, no evidence of systolic dysfunction is present after 12 weeks. Interestingly, the HFWD, with equal parts saturated, monounsaturated, and polyunsaturated FAs, induces mild cardiac hypertrophy and diastolic dysfunction after 12 weeks, which coincides with elevated serum levels of arachidonic acid. Our results suggest that the dietary FA content and composition may be a primary determinant of diastolic, but not systolic, dysfunction in animal models of diet-induced obesity.

Severe food restriction (FR) impairs cardiac performance, although the causative mechanisms remain elusive. Since proteins associated with calcium handling may contribute to cardiac dysfunction, this study aimed to evaluate whether severe FR results in alterations in the expression and activity of Ca2+-handling proteins that contribute to impaired myocardial performance. Male 60-day-old Wistar&ndash, Kyoto rats were fed a control or restricted diet (50% reduction in the food consumed by the control group) for 90 days. Body weight, body fat pads, adiposity index, as well as the weights of the soleus muscle and lung, were obtained. Cardiac remodeling was assessed by morphological measures. The myocardial contractile performance was analyzed in isolated papillary muscles during the administration of extracellular Ca2+ and in the absence or presence of a sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) specific blocker. The expression of Ca2+-handling regulatory proteins was analyzed via Western Blot. Severe FR resulted in a 50% decrease in body weight and adiposity measures. Cardiac morphometry was substantially altered, as heart weights were nearly twofold lower in FR rats. Papillary muscles isolated from FR hearts displayed mechanical dysfunction, including decreased developed tension and reduced contractility and relaxation. The administration of a SERCA2a blocker led to further decrements in contractile function in FR hearts, suggesting impaired SERCA2a activity. Moreover, the FR rats presented a lower expression of L-type Ca2+ channels. Therefore, myocardial dysfunction induced by severe food restriction is associated with changes in the calcium-handling properties in rats.

Made available in DSpace on 2019-10-04T12:38:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01. Added 1 bitstream(s) on 2019-10-09T18:34:11Z : No. of bitstreams: 1 S0100-879X2019000600605.pdf: 829319 bytes, checksum: c8a69fd5a79a5f1c6de2a9a7949e5f5e (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Obesity is often associated with changes in cardiac function; however, the mechanisms responsible for functional abnormalities have not yet been fully clarified. Considering the lack of information regarding high-saturated-fat diet-induced obesity, heart function, and the proteins involved in myocardial calcium (Ca2+) handling, the aim of this study was to test the hypothesis that this dietary model of obesity leads to cardiac dysfunction resulting from alterations in the regulatory proteins of intracellular Ca2+ homeostasis. Male Wistar rats were distributed into two groups: control (C, n=18; standard diet) and obese (Ob, n=19; high-saturated-fat diet), which were fed for 33 weeks. Cardiac structure and function were evaluated using echocardiographic and isolated papillary muscle analyses. Myocardial protein expressions of sarcoplasmic reticulum Ca2+-ATPase, phospholamban (PLB), PLB serine-16 phosphorylation, PLB threonine-17 phosphorylation, ryanodine receptor, calsequestrin, Na+/Ca2+ exchanger, and L-type Ca2+ channel were assessed by western blot. Obese rats presented 104% increase in the adiposity index (C: 4.5 +/- 1.4 vs Ob: 9.2 +/- 1.5%) and obesity-related comorbidities compared to control rats. The left atrium diameter (C: 5.0 +/- 0.4 vs Ob: 5.5 +/- 0.5 mm) and posterior wall shortening velocity (C: 36.7 +/- 3.4 vs Ob: 41.8 +/- 3.8 mm/s) were higher in the obese group than in the control. The papillary muscle function was similar between the groups at baseline and after inotropic and lusitropic maneuvers. Obesity did not lead to changes in myocardial Ca2+ handling proteins expression. In conclusion, the hypothesis was not confirmed, since the high-saturated-fat diet-induced obese rats did not present cardiac dysfunction or impaired intracellular Ca2+ handling proteins. Univ Estadual Paulista, Fac Med Botucatu, Dept Clin Med, Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biociencias Botucatu, Dept Bioestat, Botucatu, SP, Brazil Univ Estadual Paulista, Fac Med Botucatu, Dept Clin Med, Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biociencias Botucatu, Dept Bioestat, Botucatu, SP, Brazil FAPESP: FAPESP 2012/20733-0

Made available in DSpace on 2018-12-11T17:04:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-01. Added 1 bitstream(s) on 2019-10-09T18:30:31Z : No. of bitstreams: 1 S0066-782X2016004000033.pdf: 513463 bytes, checksum: d9ba48636cd68e1b4524c887cc0e4851 (MD5) Background: Right-sided heart failure has high morbidity and mortality, and may be caused by pulmonary arterial hypertension. Fractal dimension is a differentiated and innovative method used in histological evaluations that allows the characterization of irregular and complex structures and the quantification of structural tissue changes. Objective: To assess the use of fractal dimension in cardiomyocytes of rats with monocrotaline-induced pulmonary arterial hypertension, in addition to providing histological and functional analysis. Methods: Male Wistar rats were divided into 2 groups: control (C; n = 8) and monocrotaline-induced pulmonary arterial hypertension (M; n = 8). Five weeks after pulmonary arterial hypertension induction with monocrotaline, echocardiography was performed and the animals were euthanized. The heart was dissected, the ventricles weighed to assess anatomical parameters, and histological slides were prepared and stained with hematoxylin/eosin for fractal dimension analysis, performed using box-counting method. Data normality was tested (Shapiro-Wilk test), and the groups were compared with non-paired Student t test or Mann Whitney test (p < 0.05). Results: Higher fractal dimension values were observed in group M as compared to group C (1.39 ± 0.05 vs. 1.37 ± 0.04; p < 0.05). Echocardiography showed lower pulmonary artery flow velocity, pulmonary acceleration time and ejection time values in group M, suggesting function worsening in those animals. Conclusion: The changes observed confirm pulmonary-arterial-hypertension-induced cardiac dysfunction, and point to fractal dimension as an effective method to evaluate cardiac morphological changes induced by ventricular dysfunction. UNOESTE FCT/UNESP Departamento de Fisioterapia FCT/UNESP Departamento de Educação Física UNOESTE Departamento de Morfologia UNESP Faculdade de Medicina UNESP FCT/UNESP Departamento de Fisioterapia FCT/UNESP Departamento de Morfologia UNESP Faculdade de Medicina UNESP

Background: Although the beneficial effects of resistance training (RT) on the cardiovascular system are well established, few studies have investigated the effects of the chronic growth hormone (GH) administration on cardiac remodeling during an RT program. Objective: To evaluate the effects of GH on the morphological features of cardiac remodeling and Ca2+ transport gene expression in rats submitted to RT. Methods: Male Wistar rats were divided into 4 groups (n = 7 per group): control (CT), GH, RT and RT with GH (RTGH). The dose of GH was 0.2 IU/kg every other day for 30 days. The RT model used was the vertical jump in water (4 sets of 10 jumps, 3 bouts/wk) for 30 consecutive days. After the experimental period, the following variables were analyzed: final body weight (FBW), left ventricular weight (LVW), LVW/FBW ratio, cardiomyocyte cross-sectional area (CSA), collagen fraction, creatine kinase muscle-brain fraction (CK-MB) and gene expressions of SERCA2a, phospholamban (PLB) and ryanodine (RyR). Results: There was no significant (p > 0.05) difference among groups for FBW, LVW, LVW/FBW ratio, cardiomyocyte CSA, and SERCA2a, PLB and RyR gene expressions. The RT group showed a significant (p < 0.05) increase in collagen fraction compared to the other groups. Additionally, the trained groups (RT and RTGH) had greater CK-MB levels compared to the untrained groups (CT and GH). Conclusion: GH may attenuate the negative effects of RT on cardiac remodeling by counteracting the increased collagen synthesis, without affecting the gene expression that regulates cardiac Ca2+ transport. Resumo Fundamento: Apesar de os efeitos benéficos do treinamento resistido (TR) sobre o sistema cardiovascular estarem bem estabelecidos, poucos estudos têm investigado os efeitos crônicos da administração de hormônio do crescimento (GH) sobre a remodelação cardíaca durante um programa de TR. Objetivo: avaliar os efeitos do GH sobre a remodelação cardíaca em suas características morfológicas e na expressão dos genes do trânsito de Ca2+ em ratos submetidos ao TR. Métodos: Ratos Wistar machos foram divididos em 4 grupos (n = 7 por grupo): controle (CT), GH, TR e TR com GH (TRGH). A dose de GH foi de 0,2 UI/kg, a cada dois dias, por 30 dias. O modelo de TR utilizado foi o salto vertical em água (4 séries de 10 saltos, 3 vezes/semana) durante 30 dias consecutivos. Após o período experimental, as seguintes variáveis foram analisadas: peso corporal final (PCF), peso do ventrículo esquerdo (PVE), razão PVE/PCF, área seccional de cardiomiócitos (ASC), fração de colágeno, creatina quinase fração músculo-cérebro (CK-MB) e expressão gênica de SERCA2a, fosfolambam (PLB) e rianodina (RyR). Resultados: Não houve diferença significativa (p > 0,05) entre os grupos para PCF, PVE, razão PVE/PCF, ASC, e expressão gênica de SERCA2a, PLB e RyR. O grupo TR mostrou um significativo aumento (p < 0,05) da fração de colágeno em comparação aos outros. Além disso, os grupos treinados (TR e TRGH) apresentaram maiores níveis de CK-MB em comparação aos não treinados (CT e GH). Conclusão: Esses resultados indicam que o GH pode atenuar os efeitos negativos do TR na remodelação cardíaca por contrabalançar o aumento da síntese de colágeno, sem afetar a expressão de genes que regulam o trânsito de Ca2+ cardíaco.

Made available in DSpace on 2018-11-26T17:48:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 American Heart Association Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Pathological cardiac hypertrophy leads to derangements in lipid metabolism that may contribute to the development of cardiac dysfunction. Since previous studies, using high saturated fat diets, have yielded inconclusive results, we investigated whether provision of a high-unsaturated fatty acid ( HUFA) diet was sufficient to restore impaired lipid metabolism and normalize diastolic dysfunction in the pathologically hypertrophied heart. Male, Wistar rats were subjected to supra-valvar aortic stenosis ( SVAS) or sham surgery. After 6 weeks, diastolic dysfunction and pathological hypertrophy was confirmed and both sham and SVAS rats were treated with either normolipidic or HUFA diet. At 18 weeks post-surgery, the HUFA diet failed to normalize decreased E/A ratios or attenuate measures of cardiac hypertrophy in SVAS animals. Enzymatic activity assays and gene expression analysis showed that both normolipidic and HUFA-fed hypertrophied hearts had similar increases in glycolytic enzyme activity and down-regulation of fatty acid oxidation genes. Mass spectrometry analysis revealed depletion of unsaturated fatty acids, primarily linoleate and oleate, within the endogenous lipid pools of normolipidic SVAS hearts. The HUFA diet did not restore linoleate or oleate in the cardiac lipid pools, but did maintain body weight and adipose mass in SVAS animals. Overall, these results suggest that, in addition to decreased fatty acid oxidation, aberrant unsaturated fatty acid metabolism may be a maladaptive signature of the pathologically hypertrophied heart. The HUFA diet is insufficient to reverse metabolic remodeling, diastolic dysfunction, or pathologically hypertrophy, possibly do to preferentially partitioning of unsaturated fatty acids to adipose tissue. Sao Paulo State Univ, Dept Internal Med, Botucatu, SP, Brazil Univ Washington, Dept Anesthesiol & Pain Med, Mitochondria & Metab Ctr, Seattle, WA 98195 USA Sao Paulo State Univ, Dept Biostat, Botucatu, SP, Brazil Univ Sao Paulo, Dept Biochem, Sao Paulo, SP, Brazil Ursinus Coll, Hlth & Exercise Physiol Dept, Heart & Muscle Metab Lab, Collegeville, PA 19426 USA Sao Paulo State Univ, Dept Internal Med, Botucatu, SP, Brazil Sao Paulo State Univ, Dept Biostat, Botucatu, SP, Brazil American Heart Association: 14SDG18590020 FAPESP: 2012/19679-0 FAPESP: 2014/06030-1

Made available in DSpace on 2015-08-26T19:19:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-01. Added 1 bitstream(s) on 2015-08-31T13:04:47Z : No. of bitstreams: 1 S0066-782X2015000200002.pdf: 370986 bytes, checksum: d47be1fbbab3d3f9d1220187f718afde (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundamento: Muitos pesquisadores buscam métodos para a seleção de grupos homogêneos de animais em pesquisas experimentais, fato que se justifica por ser a homogeneidade pré-requisito indispensável à casualização de tratamentos. A ausência de métodos robustos, que atendam a princípios estatísticos e biológicos, faz com que os pesquisadores utilizem métodos empíricos ou subjetivos, influenciando seus resultados. Objetivo: Desenvolver modelo estatístico multivariado para a seleção de grupo homogêneo de animais para pesquisas experimentais e elaborar pacote computacional que o operacionalize. Métodos: O conjunto de dados ecocardiográficos de 115 ratos Wistar, machos, com estenose aórtica (EAo) supravalvular foi utilizado para exemplificar o desenvolvimento do modelo. Inicialmente, os dados foram padronizados, tornando-se adimensionais. Em sequência, submeteu-se a matriz de variabilidade do conjunto à análise de componentes principais (ACP) buscando-se reduzir o espaço paramétrico e conservar a variabilidade relevante. Essa técnica estabeleceu um novo sistema cartesiano em que os animais foram alocados e, finalmente, construiu-se a região de confiança (elipsoide) para o perfil de respostas homogêneas dos animais. Os que se situaram no interior do elipsoide foram considerados pertencentes ao grupo homogêneo; caso contrário, espúrios ao grupo. Resultados: A ACP estabeleceu oito eixos descritores que representaram a variabilidade acumulada dos dados em 88,71%. A alocação dos animais no novo sistema e a construção da região de confiança revelou a presença de seis espúrios ao lote homogêneo formado por 109 animais. Conclusão: O critério biométrico proposto mostra-se eficiente, pois considera o animal como um todo, analisando conjuntamente todos os parâmetros mensurados, além de apresentar pequena frequência de descartes. Background: Several researchers seek methods for the selection of homogeneous groups of animals in experimental studies, a fact justified because homogeneity is an indispensable prerequisite for casualization of treatments. The lack of robust methods that comply with statistical and biological principles is the reason why researchers use empirical or subjective methods, influencing their results. Objective: To develop a multivariate statistical model for the selection of a homogeneous group of animals for experimental research and to elaborate a computational package to use it. Methods: The set of echocardiographic data of 115 male Wistar rats with supravalvular aortic stenosis (AoS) was used as an example of model development. Initially, the data were standardized, and became dimensionless. Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability. That technique established a new Cartesian system into which the animals were allocated, and finally the confidence region (ellipsoid) was built for the profile of the animals’ homogeneous responses. The animals located inside the ellipsoid were considered as belonging to the homogeneous batch; those outside the ellipsoid were considered spurious. Results: The PCA established eight descriptive axes that represented the accumulated variance of the data set in 88.71%. The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals. Conclusion: The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate. Universidade Estadual Paulista Instituto de Ciências Biológicas Departamento de Bioestatística Universidade Estadual Paulista Faculdade de Medicina de Botucatu Departamento de Clínica Médica Universidade Estadual Paulista Instituto de Ciências Biológicas Departamento de Bioestatística Universidade Estadual Paulista Faculdade de Medicina de Botucatu Departamento de Clínica Médica

Made available in DSpace on 2015-12-07T15:31:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2015. Added 1 bitstream(s) on 2015-12-07T15:52:26Z : No. of bitstreams: 1 PMC4577087.pdf: 2614289 bytes, checksum: 1c86455b56e7c03cdf60dc25655c497a (MD5) Fundação de Apoio à Pesquisa e Estudos na Área da Saúde (FAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Obesity has been shown to impair myocardial performance. Some factors have been suggested as responsible for possible cardiac abnormalities in models of obesity, among them beta-adrenergic (βA) system, an important mechanism of regulation of myocardial contraction and relaxation. The objective of present study was to evaluate the involvement of βA system components in myocardial dysfunction induced by obesity. Thirty-day-old male Wistar rats were distributed in control (C, n = 25) and obese (Ob, n = 25) groups. The C group was fed a standard diet and Ob group was fed four unsaturated high-fat diets for 15 weeks. Cardiac function was evaluated by isolated papillary muscle preparation and βA system evaluated by using cumulative concentrations of isoproterenol and Western blot. After 15 weeks, the Ob rats developed higher adiposity index than C rats and several comorbidities; however, were not associated with changes in systolic blood pressure. Obesity caused structural changes and the myocardial responsiveness to post-rest contraction stimulus and increased extracellular calcium (Ca2+) was compromised. There were no changes in cardiac function between groups after βA stimulation. The obesity was not accompanied by changes in protein expression of G protein subunit alpha (Gsα) and βA receptors (β1AR and β2AR). In conclusion, the myocardial dysfunction caused by unsaturated high-fat diet-induced obesity, after 15 weeks, is not related to βAR system impairment at the receptor-signalling pathway. Center of Physical Education and Sports, Department of Sports, Federal University of Espírito Santo, Vitória, Espírito Santo, Brazil Department of Clinical and Cardiology, School of Medicine, UNESP- Univ. Estadual Paulista, Botucatu, São Paulo, Brazil Instituto de Ciências da Saúde, Federal University of Mato Grosso, Sinop, Mato Grosso, Brazil Department of Clinical and Cardiology, School of Medicine, UNESP- Univ. Estadual Paulista, Botucatu, São Paulo, Brazil FAPES: 53618009/2011 FAPESP: 2012/16647-0

Made available in DSpace on 2015-02-02T12:39:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-01Bitstream added on 2015-02-02T13:07:53Z : No. of bitstreams: 1 S0066-782X2014001900007.pdf: 795301 bytes, checksum: 90ebcac34be2de662b8562560ceb85ee (MD5) Item merged in doublecheck by Felipe Arakaki (fe.arakaki@gmail.com) on 2015-11-12T15:36:25Z Item was identical to item(s): 113577, 108894 at handle(s): http://hdl.handle.net/11449/114469, http://hdl.handle.net/11449/109811 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundamento: A ativação do sistema beta-adrenérgico promove a estimulação da proteína G, que, via adenosina monofosfato cíclico (AMPc), altera a estrutura da proteina quinase A (PKA) e acarreta a fosforilação da fosfolambam PLB). Essa proteína participa do sistema envolvido no controle de cálcio intracelular, em células musculares, sendo a principal reguladora da atividade da bomba de cálcio do retículo sarcoplasmático. Na obesidade ocorre ativação do sistema beta-adrenérgico por influência do aumento da leptina, acarretando, consequentemente, maior fosforilação da fosfolambam miocárdica, via AMPc-PKA. Objetivo: Investigar, na obesidade, o envolvimento das proteínas que regulam o grau de fosforilação do PLB decorrente da ativação beta-adrenérgica. A hipótese do estudo é que há desequilíbrio entre a fosforilação e a desfosforilação da fosfolambam, com predomínio da fosforilação da proteína. Métodos: Ratos Wistar machos foram randomizados e distribuídos em dois grupos: controle (n = 14), alimentado com dieta normocalórica, e obeso (n = 13), com um ciclo de quatro dietas hiperlipídicas insaturadas. A obesidade foi determinada pelo índice de adiposidade, e as expressões proteicas de fosfatase 1 (PP-1), PKA, PLB, fosfolambam fosforilado na serina 16 (pPLB-ser16) foram realizadas por Western Blot. Resultados: A obesidade acarretou intolerância à glicose, hiperinsulinemia, hipertrigliceridemia, hiperleptinemia e não alterou a expressão proteica de PKA, PP-1, PLB, pPLB-ser16. Conclusão: A obesidade não promove desequilíbrio entre a fosforilação e a desfosforilação, via beta-adrenérgica, do PLB miocárdico. (Arq Bras Cardiol. 2014; 103(1):41-50) Background:The activation of the beta-adrenergic system promotes G protein stimulation that, via cyclic adenosine monophosphate (cAMP), alters the structure of protein kinase A (PKA) and leads to phospholamban (PLB) phosphorylation. This protein participates in the system that controls intracellular calcium in muscle cells, and it is the primary regulator of sarcoplasmic reticulum calcium pump activity. In obesity, the beta-adrenergic system is activated by the influence of increased leptin, therefore, resulting in higher myocardial phospholamban phosphorylation via cAMP-PKA. Objective:To investigate the involvement of proteins which regulate the degree of PLB phosphorylation due to beta-adrenergic activation in obesity. In the present study, we hypothesized that there is an imbalance between phospholamban phosphorylation and dephosphorylation, with prevalence of protein phosphorylation. Methods:Male Wistar rats were randomly distributed into two groups: control (n = 14), fed with normocaloric diet; and obese (n = 13), fed with a cycle of four unsaturated high-fat diets. Obesity was determined by the adiposity index, and protein expressions of phosphatase 1 (PP-1), PKA, PLB, phosphorylated phospholamban at serine16 (PPLB-Ser16) were assessed by Western blot. Results:Obesity caused glucose intolerance, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia and did not alter the protein expression of PKA, PP-1, PLB, PPLB-Ser16. Conclusion:Obesity does not promote an imbalance between myocardial PLB phosphorylation and dephosphorylation via beta-adrenergic system. Universidade Estadual Paulista Faculdade de Medicina de Botucatu Departamento de Clínica Médica Universidade Federal do Espírito Santo Centro de Educação Física e Desportos Universidade Estadual Paulista Faculdade de Medicina de Botucatu Departamento de Clínica Médica

Made available in DSpace on 2018-11-27T21:47:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Obesity is a worldwide pandemic associated with high incidence of cardiovascular disease. The mechanisms by which the obesity leads cardiac dysfunction are not fully elucidated and few studies have evaluated the relationship between obesity and proteins involved in myocardial -adrenergic (A) system. The purpose of this study was to evaluate the cardiac function and A pathway components in myocardium of obese rats. Male Wistar rats were distributed into two groups: control (n=17; standard diet) and obese (n=17; saturated high-fat diet) fed for 33weeks. Nutritional profile and comorbidities were assessed. Cardiac structure and function was evaluated by macroscopic postmortem, echocardiographic and isolated papillary muscle analyzes. Myocardial protein expression of (1)- and (2)-adrenergic receptors, Gs protein, adenylate cyclase (AC) and protein kinase A (PKA) was performed by Western blot. Cardiac cyclic adenosine monophosphate (cAMP) levels and PKA activity were assessed by ELISA. Obese rats showed increased adiposity index (P

Food restriction (FR) has been shown to impair myocardial performance. However, the mechanisms behind these changes in myocardial function due to FR remain unknown. Since myocardial L-type Ca2+ channels may contribute to the cardiac dysfunction, we examined the influence of FR on L-type Ca2+ channels. Male 60-day-old Wistar rats were fed a control or a restricted diet (daily intake reduced to 50% of the amount of food consumed by the control group) for 90 days. Myocardial performance was evaluated in isolated left ventricular papillary muscles. The function of myocardial L-type Ca2+ channels was determined by using a pharmacological Ca2+ channel blocker, and changes in the number of channels were evaluated by mRNA and protein expression. FR decreased final body weights, as well as weights of the left and right ventricles. The Ca2+ channel blocker diltiazem promoted a higher blockade on developed tension in FR groups than in controls. The protein content of L-type Ca2+ channels was significantly diminished in FR rats, whereas the mRNA expression was similar between groups. These results suggest that the myocardial dysfunction observed in previous studies with FR animals could be caused by downregulation of L-type Ca2+ channels.