No abstract

Background: The effects of non-pharmacological interventions such as calorie restriction and exercise training on health and prevention of cardiovascular diseases have been investigated in clinical and experimental studies. Objective: To analyze the influence of intermittent fasting and exercise training on functional fitness, glycemia and cardiac remodeling. Methods: Wistar rats (n=60) were randomly divided into four groups: control, exercise training (ET), intermittent fasting (IF) and exercise training plus intermittent fasting (ETI). Over 12 weeks, control and ET animals were fed daily a standard commercial diet ad libitum, while IF and ETI animals were fed every other day. In addition, the ET and ETI groups were submitted to a running protocol on a treadmill. After this period, functional fitness, nutritional parameters and blood glucose levels were analyzed. In addition to heart morphology, myocardial protein expression of extracellular signalregulated kinase (ERK) and c-Jun N-terminal kinase (JNK) was assessed by Western-blot. The results were analyzed using two-way ANOVA and Student-Newman-Keuls test. The level of significance considered was 5%. Results: Exercise training increased functional fitness in the ET and ETI groups and promoted cardiac fibrosis. The combination of intermittent fasting and exercise training resulted in a smaller area under the blood glucose curve and reduced cardiomyocyte cross-sectional area and interstitial collagen fraction in the ETI group compared to ET. ERK and JNK expression levels were similar among groups (p>0.05). Conclusions: Intermittent fasting is associated with improved glucose tolerance and attenuates cardiac remodeling induced by exercise training (Arq Bras Cardiol. 2020; 115(2):184-193

Background: Obesity has been associated with chronic activation of the renin-angiotensin-aldosterone system and with significant changes in cardiac performance. Objective: To assess the impact of a blockade of angiotensin-II receptor type 1 (AT 1 receptor) on morphology and on myocardial functional performance in rats with high-fat diet-induced obesity. Methods: Wistar rats (n=48) were submitted to control (2.9 kcal/g) or high-fat (3.6 kcal/g) diet for 20 weeks. After the 16 th week they were divided into four groups: Control (CO), Obese (OB), Control Losartan (CL) and Obese Losartan (OL). CL and OL received losartan (30 mg/kg/day) in drinking water for four weeks. Subsequently, body composition, systolic blood pressure (SBP) and echocardiographic variables were analyzed. Papillary muscle function was assessed at baseline with 2.50 mM calcium concentration ([Ca 2+ ] o) and after inotropic maneuvers: post-pause potentiation (PPP), [Ca 2+ ] o elevation, and during beta-adrenergic stimulation with isoproterenol. Analysis of the results was performed by the Two-Way ANOVA and by the appropriate comparison test. The level of significance was set at 5%. Results: Although SBP change had been not maintained at the end of the experiment, obesity was associated with cardiac hypertrophy and with increased left ventricle posterior wall shortening velocity. In the study of papillary muscles in basal condition, CL showed lower developed tension maximum negative variation velocity (-dT/dt) than CO. The 60s PPP promoted lower-dT/dt and maximum developed tension (DT) in OB and CL compared with CO, and higher relative DT variation and maximum positive variation velocity (+dT/dt) in OL compared with CL and OB. Under 1.5, 2.0, and 2.5mM [Ca 2+ ] o , the OL group showed higher-dT/dt than CL. Conclusion: Losartan improves myocardial function in high-fat diet-induced obesity.

No abstract

We evaluated the influence of aerobic physical exercise (EX) on gene-encoding proteins associated with oxidative stress in diaphragm muscle of rats with aortic stenosis-induced heart failure (HF). Wistar male rats were divided into four groups: Control sedentary (C); Control exercise (C-Ex); Sedentary aortic stenosis (AS); Aortic stenosis exercise (AS-Ex). Exercised rats trained 5 times a week for 10 weeks on a treadmill. Statistical analysis was performed by ANOVA or Kruskal–Wallis test. In the final echocardiogram, animals with aortic stenosis subjected to exercise demonstrated improvement in systolic function compared to the sedentary aortic stenosis group. In diaphragm muscle, the activity of antioxidant enzymes, malondialdehyde malondialdehyde concentration, protein carbonylation, and protein expression of p65 and its inhibitor IκB did not differ between groups. Alterations in gene expression of sources that generate reactive species of oxygen were observed in AS-Ex group, which showed decreased mRNA abundance of NOX2 and NOX4 compared to the aortic stenosis group (p < 0.05). We concluded that aerobic exercise has a positive impact during heart failure, ameliorating systolic dysfunction and biomarkers of oxidative stress in diaphragm muscle of rats with aortic stenosis-induced heart failure.

Extensive evidence has shown that high‐fat diet is associated with chronic activation of the renin‐angiotensin system (RAS) and left ventricular remodeling. This study was developed to evaluate the impact of angiotensin‐1 (AT1) receptor antagonism on myocardial function in rats with high‐fat diet‐induced obesity.MethodsMale Wistar rats (n=48) were fed a control (2.9 kcal/g, C) or high‐fat (3.6 kcal/g, O) diet for 20 weeks. After the 16th week, the rats were assigned into four groups: C, O, CL, and OL. CL and OL groups received Losartan (30 mg/kg/day) in drinking water during four weeks. At the end of the experiment, body composition and systolic blood pressure were assessed, and echocardiogram analysis was performed. Mechanical performance of papillary muscles was evaluated under basal condition with 2.5 mM calcium ([Ca+2])o and after inotropic stimulation: post‐rest contraction (PRC) and change in extracellular [Ca+2]o from 1.0 to 2.5 mM.ResultsBoth O and OL groups presented higher body weight and adiposity than their respective controls (p<0.05). Systolic blood pressure did not differ among groups. O and OL groups had greater left ventricular weight‐to‐tibia length ratio and posterior wall shortening velocity (C 42.92±4.45; O 48.72±4.81; CL 42.82±3.60; OL 47.96±4.03 mm/s). In papillary muscles evaluation, CL presented reduced negative tension derivative (‐dT/dt) in comparison to the C group at basal condition. After 60 seconds of PRC, both O and CL had lower relative variations in ‐dT/dt (C 55.9±20.9; O 47.1±13.3; CL 47.7±15.9; OL 51.1±14.5%) and peak developed tension than C. Also, OL had higher relative variation in DT than CL and O (C 65.7±23.6; O 56.3±13.9; CL 58.0±17.4; OL 66.4±17.4%), while variation of positive tension derivative (+dT/dt) was increased in OL compared to CL and O groups. After increasing [Ca2+]o to 2.0 and 2.5 mM, the relative variation in DT and +dT/dt were higher in OL than CL and O, respectively. OL showed increased ‐dT/dt in comparison to CL at extracellular calcium concentrations of 1.5, 2.0, and 2.5 mM.ConclusionAngiotensin II antagonism with losartan improves myocardial functional performance in rats with high‐fat diet induced‐obesity.Support or Funding InformationFinancial support: CAPES; CNPq; FUNDECT/MS.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Introdução: Há evidências que jejum intermitente (JI) e treinamento intervalado de alta intensidade (HIIT) podem promover mudanças no músculo esquelético e na densidade óssea. Entretanto, a participação da miostatina, um regulador negativo da massa muscular, na modulação dessas alterações induzidas pela associação de JI e HIIT ainda é pouco conhecida. Objetivo: Avaliar a influência do JI e do HIIT sobre expressão de miostatina e modulação do trofismo muscular e da densidade óssea em ratos. Métodos: Ratos Wistar machos (n=40, 60 dias) foram divididos em: Controle (C), Jejum Intermitente (JI), Treinamento Intervalado de Alta Intensidade (T) e Treinamento Intervalado de Alta Intensidade + Jejum Intermitente (TJI). Os grupos C e T receberam dieta padrão para roedores ad libitum; JI e TJI receberam a mesma ração à vontade por períodos de 24 horas alternados com jejum de mesma duração. Os grupos T e TJI realizaram protocolo de HIIT em esteira rolante (5 vezes/semana). Após 12 semanas, foram analisadas densidade mineral óssea (DMO) do úmero do membro anterior direito (raios-X de dupla energia - DEXA), área seccional transversa das fibras (análise histomorfométrica) e expressão da proteína miostatina (Western blot) no músculo gastrocnêmio. Análise estatística: ANOVA de duas vias e Tukey. O protocolo experimental foi aprovado pela Comissão de Ética no Uso de Animais da Universidade Federal de Mato Grosso do Sul (CEUA/UFMS), protocolo n° nº 995/2018. Resultados: DMO do úmero foi menor no grupo JI que em C e maior em TJI que em JI (C:1,15±0,04; JI:1,01±0,15; T:1,15±0,09; TJI:1,16±0,07 g/cm 3 ). A área seccional transversa das fibras foi menor em JI que em C e menor em TJI que em T. A expressão da miostatina foi maior no grupo TJI quando comparado ao grupo T (C:1,00±0,31; JI:1,32±0,32; T:0,89±0,34; TJI:1,72±0,46 unidades arbitrárias). Conclusão: Como fator isolado, o JI reduz a DMO e o trofismo muscular. A associação de HIIT ao JI atenua a redução de DMO e modula a expressão de miostatina no músculo gastrocnêmio, porém não previne a atrofia muscular. Apoio: UFMS, CAPES (Cód.001), CNPq.   Palavras-chave: Exercício.  Conteúdo mineral ósseo.  

Introdução: Há evidências que a creatina associada ao treinamento induz alterações funcionais e morfológicas no músculo esquelético. Entretanto, não estão bem definidos os efeitos da suplementação com creatina durante o treinamento resistido sobre o colágeno intersticial e a expressão de cadeias pesadas de miosina (MyHC) no músculo esquelético. Objetivo: Analisar a influência da suplementaçã com creatina sobre a expressão de MyHC e fração intersticial de colágeno em diferentes músculos esqueléticos de ratos submetidos a treinamento físico resistido. Material e Métodos: Ratos Wistar (n=24) foram distribuídos em quatro grupos: Controle (C), Creatina (Cr), Treinamento Resistido (TR) e Treinamento Resistido e Creatina (Tcr). Os grupos C e TR receberam dieta comercial padrão, enquanto Cr e Tcr receberam dieta com 2% de creatina. Os animais TR e Tcr realizaram protocolo de treinamento resistido em escada, 3x/semana, por 12 semanas. Posteriormente, foi realizada eutanásia dos animais e amostras de sóleo e gastrocnêmio foram usadas para análise histológica e expressão de MyHC por meio de eletroforese. Estatística: Two-Way ANOVA e Tukey. Significância de 5%. O protocolo experimental foi aprovado pela Comissão de Ética no Uso de Animais da Universidade Federal de Mato Grosso do Sul (CEUA/UFMS), protocolo n° 873/2017. Resultados: No gastrocnêmio, a porcentagem de MyHC IIx foi maior no TR do que em C (C: 6,25±2,69; Cr: 8,89±2,94; TR: 11,47±3,73; Tcr: 12,30±6,58 %). No sóleo, a taxa de MyHC IIa não diferiu entre os grupos. A fração intersticial de colágeno de ambos os músculos avaliados mostrou-se maior em resposta ao treinamento físico resistido, per se. Conclusão: A prática de treinamento físico resistido resultou em remodelação intersticial em diferentes tipos de músculo esquelético e maior expressão de isoformas de MyHC Iix no músculo gastrocnêmio em ratos expostos ou não à suplementação com creatina. Apoio: UFMS, CAPES (Cód.001), CNPq.