Edson Castardeli

Involvement of L-type calcium channel and SERCA2a in myocardial dysfunction induced by obesity.

Obesity has been shown to impair myocardial performance. Nevertheless, the mechanisms underlying the participation of calcium (Ca2+) handling on cardiac dysfunction in obesity models remain unknown. L‐type Ca2+ channels and sarcoplasmic reticulum (SR) Ca2+‐ATPase (SERCA2a), may contribute to the cardiac dysfunction induced by obesity. The purpose of this study was to investigate whether myocardial dysfunction in obese rats is related to decreased activity and/or expression of L‐type Ca2+ channels and SERCA2a. Male 30‐day‐old Wistar rats were fed standard (C) and alternately four palatable high‐fat diets (Ob) for 15 weeks. Obesity was determined by adiposity index and comorbidities were evaluated. Myocardial function was evaluated in isolated left ventricle papillary muscles under basal conditions and after inotropic and lusitropic maneuvers. L‐type Ca2+ channels and SERCA2a activity were determined using specific blockers, while changes in the amount of channels were evaluated by Western blot analysis. Phospholamban (PLB) protein expression and the SERCA2a/PLB ratio were also determined. Compared with C rats, the Ob rats had increased body fat, adiposity index and several comorbidities. The Ob muscles developed similar baseline data, but myocardial responsiveness to post‐rest contraction stimulus and increased extracellular Ca2+ was compromised. The diltiazem promoted higher inhibition on developed tension in obese rats. In addition, there were no changes in the L‐type Ca2+ channel protein content and SERCA2a behavior (activity and expression). In conclusion, the myocardial dysfunction caused by obesity is related to L‐type Ca2+ channel activity impairment without significant changes in SERCA2a expression and function as well as L‐type Ca2+ protein levels. J. Cell. Physiol. 226: 2934–2942, 2011.

Disfunção miocárdica e alterações no trânsito de cálcio intracelular em ratos obesos

FUNDAMENTO: Varios mecanismos tem sido propostos contribuir para a disfuncao cardiaca em modelos de obesidade, tais como alteracoes nas proteinas do trânsito de calcio (Ca+2) e nos receptores beta-adrenergicos. Todavia, o papel desses fatores no desenvolvimento da disfuncao miocardica induzida pela obesidade ainda nao esta claro. OBJETIVO: Este estudo pretende investigar se a obesidade induzida por um ciclo de dieta hipercaloricas resulta em disfuncao cardiaca. Alem disso, foi avaliado se essa alteracao funcional em ratos obesos esta relacionada com o prejuizo do trânsito de Ca+2 e do sistema beta-adrenergico. METODOS: Ratos Wistar machos, 30 dias de idade, foram alimentados com racao padrao (C) e um ciclo de cinco dietas hipercaloricas (Ob) por 15 semanas. A obesidade foi definida pelo aumento da porcentagem de gordura corporal dos ratos. A funcao cardiaca foi avaliada mediante analise isolada do musculo papilar do ventriculo esquerdo em condicoes basais e apos manobras inotropicas e lusitropicas. RESULTADOS: Em comparacao com o grupo controle, os ratos obesos apresentaram aumento da gordura corporal e intolerância a glicose. Os musculos dos ratos obesos desenvolveram valores basais semelhantes; entretanto, as respostas miocardicas ao potencial pos-pausa e aumento de Ca+2 extracelular foram comprometidas. Nao houve alteracoes na funcao cardiaca entre os grupos apos a estimulacao beta-adrenergica. CONCLUSAO: A obesidade promove disfuncao cardiaca relacionada com alteracoes no trânsito de Ca+2 intracelular. Esse prejuizo funcional e provavelmente ocasionado pela reducao da atividade da bomba de Ca+2 do reticulo sarcoplasmatico (SERCA2a) via Ca+2 calmodulina-quinase.

Obesity Resistance Promotes Mild Contractile Dysfunction Associated with Intracellular Ca2+ Handling

Background Diet-induced obesity is frequently used to demonstrate cardiac dysfunction. However, some rats, like humans, are susceptible to developing an obesity phenotype, whereas others are resistant to that. Objective To evaluate the association between obesity resistance and cardiac function, and the impact of obesity resistance on calcium handling. Methods Thirty-day-old male Wistar rats were distributed into two groups, each with 54 animals: control (C; standard diet) and obese (four palatable high-fat diets) for 15 weeks. After the experimental protocol, rats consuming the high-fat diets were classified according to the adiposity index and subdivided into obesity-prone (OP) and obesity-resistant (OR). Nutritional profile, comorbidities, and cardiac remodeling were evaluated. Cardiac function was assessed by papillary muscle evaluation at baseline and after inotropic maneuvers. Results The high-fat diets promoted increase in body fat and adiposity index in OP rats compared with C and OR rats. Glucose, lipid, and blood pressure profiles remained unchanged in OR rats. In addition, the total heart weight and the weight of the left and right ventricles in OR rats were lower than those in OP rats, but similar to those in C rats. Baseline cardiac muscle data were similar in all rats, but myocardial responsiveness to a post-rest contraction stimulus was compromised in OP and OR rats compared with C rats. Conclusion Obesity resistance promoted specific changes in the contraction phase without changes in the relaxation phase. This mild abnormality may be related to intracellular Ca2+ handling.

O Programa de Pós-Graduação em Educação Física / UFES: Pesquisa e ensino em atividade física & saúde

A pesquisa e a formacao de recursos humanos em atividade fisica e saude tem importância significativa para o desenvolvimento da pos-graduacao em educacao fisica no pais. O presente artigo apresenta os laboratorios e linhas de pesquisa do Programa de Pos-Graduacao em Educacao Fisica da Universidade Federal do Espirito Santo (PPGEF/UFES) com aderencia a esta tematica. Sao descritos o contexto, acoes e motivacoes que possibilitaram a abertura da area de concentracao em Educacao Fisica, movimento corporal humano e saude , suas respectivas linhas de pesquisa, os principios gerais adotados na formacao de novos pesquisadores, as tematicas especificas de cada grupo e as parcerias e redes de pesquisa estabelecidas. Como conclusao, indicamos o potencial de contribuicao das linhas de pesquisa do PPGEF/UFES para o conhecimento sobre o tema e o desenvolvimento regional.