Leslie Andrews Portes

Swimming training attenuates remodeling, contractile dysfunction and congestive heart failure in rats with moderate and large myocardial infarctions.

1 The aim of the present study was to evaluate the effect of swimming on myocardial remodelling after myocardial infarction (MI) in female rats induced by coronary occlusion, which was not performed in sham rats. 2 Rats were divided in six groups, three sedentary (sham (SSh; n = 14), moderate infarct (SMI; n = 8) and large infarct (SLI; n = 10)) and three trained (sham (TSh; n = 16), moderate infarct (TMI; n = 9) and large infarct (TLI; n = 8)) groups. Training (8 weeks, 60 min/day, 5 days/week) was initiated 4 weeks after MI or sham operation. Training did not affect mortality rate, but attenuated the increases in atrial/bodyweight (SSh: 0.07 ± 0.02; TSh: 0.07 ± 0.02; SMI: 0.11 ± 0.03; TMI: 0.09 ± 0.03; SLI: 0.17 ± 0.09; TLI: 0.10 ± 0.05 mg/g) and right ventricular/bodyweight (SSh: 0.15 ± 0.02; TSh: 0.17 ± 0.02; SMI: 0.17 ± 0.07; TMI: 0.20 ± 0.03; SLI: 0.29 ± 0.13; TLI: 0.22 ± 0.08 mg/g) ratios. Myocardial infarction increased pulmonary and myocardial water content in infarcted sedentary animals, whereas no changes were observed in trained infarcted rats. Sedentary infarcted rats showed inotropic and lusitropic depression proportional to the size of the infarct (SSh > SMI > SLI), whereas no differences were noted in trained rats (TLI = TMI = TSh). Indeed, in sedentary rats there was depression of +dT/dt (SSh: 68 ± 25; TSh: 72 ± 21; SMI: 53 ± 20; TMI: 77 ± 30; SLI: 33 ± 15; TLI: 57 ± 22 g/mm2 per s) and –dT/dt (SSh: 33 ± 13; TSh: 36 ± 11; SMI: 24 ± 5; TMI: 35 ± 11; SLI: 15 ± 4; TLI: 32 ± 11 g/mm2 per s) compared with trained rats. 3 In conclusion, swimming clearly favoured post‐MI cardiac remodelling, attenuated myocardial hypertrophy, contractile and relaxation dysfunction and prevented pulmonary congestion.

Anthropometric and physical fitness characteristics of young male soccer players

The objective of this study was to determine anthropometric and physical fitness characteristics of Brazilian male children and adolescents at the beginning of soccer training. In this study, 282 male soccer players ranging in age from 10 to 13 years were evaluated. The athletes participated in a formal soccer training program 3 times per week, with each training lasting 3 hours. Anthropometric and physical fitness parameters were obtained. The boys were divided into age classes and prevalence data were analyzed using Pearson’s chi-square test. Parametric data were compared by one-way ANOVA or the Kruskal-Wallis test, when necessary. The results are expressed as the mean ± standard deviation and a p value <0.05 was considered to be significant. Growth, development, body adiposity and physical fitness characteristics were adequate and proportional to age among the boys studied (p<0.05). It was concluded that anthropometric and physical fitness characteristics of young male elite soccer players improve with and are proportional to age. Children and adolescents greatly benefit from regular physical activity. The present results show that young male soccer players present adequate anthropometric conditions and physical fitness prior to the initiation of formal training at soccer clubs.

The action of pre-exercise low-level laser therapy (LLLT) on the expression of IL-6 and TNF-α proteins and on the functional fitness of elderly rats subjected to aerobic training

The aim of the present study was to determine whether low-level laser therapy (LLLT), when used in conjunction with aerobic training, interferes with the expression of inflammatory markers IL-6 and TNF-α, thereby influencing the performance of old rats participating in swimming. A total of 30 Wistar rats (Rattus norvegicus albinus) were used for this study: 24 aged rats, and 6 young rats. The older animals were randomly divided into four groups designated as follows: aged-control, aged-exercise, aged-LLLT, aged-LLLT/exercise group, and young-control animals. Aerobic capacity (VO2max) was analyzed before and after training period. The aged-exercise and aged-LLLT/exercise groups were trained for 6xa0weeks. LLLT laser was applied before each training session with 808 nm and 4xa0J of energy to the indicated groups throughout training. The rats were euthanized, and muscle tissue and serum were collected for muscle cross-sectional area and IL-6 and TNF-α protein analysis. In VO2 showed statistical difference between young- and aged-control groups (used as baseline) (pu2009<u20090.05). The same difference can be observed in the young control group compared with all intervention groups (exercise, LLLT and LLLTu2009+u2009exercise). In comparison with the aged-control group, a difference was observed only for comparison with the exercise group (pu2009<u20090.05), and exercise associated with LLLT group (pu2009<u20090.001). Levels of IL-6 and TNF-α for the aged-exercise and the aged-LLLT/exercise groups were significantly decreased compared to the aged-control group (pu2009<u20090.05). Analysis of the transverse section of the gastrocnemius muscle showed a significant difference between the aged-exercise and aged-LLLT/exercise groups (pu2009<u20090.001). These results suggest that laser therapy in conjunction with aerobic training may provide a therapeutic approach for reducing the inflammatory markers (IL-6 and TNF-α), however, LLLT without exercise was not able to improve physical performance of aged rats.

O Treinamento físico por natação atenua o remodelamento miocárdico e congestão pulmonar em ratas wistar com insuficiência cardíaca secundária a infarto do miocárdio

OBJECTIVEnTo evaluate the effects of swimming on pulmonary water content in animals with heart failure (HF) after myocardial infarction (MI).nnnMETHODSnAfter coronary occlusion, MI size 20% 40% of the LV large. The animals swam for 60 min/day, 5 days/week for 8 weeks. The wet weight of lung, liver, atriums, LV and right ventricle (RV) as well as the dry weight of the liver and lung were determined. ANOVA and Tukey test were used for statistical analysis.nnnRESULTSnAn increase in the atrium/body weight ratio was noted in the sedentary animals with moderate (MImod-SED: n=8) and large (MIlg-SED: n=10) infarctions in comparison to the sedentary control (C-SED: n=14) and trained (C-TR: n=16) rats. An increase in the RV/body weight and LV/body weight ratios was noted in the MIlg-SED. The heart/body weight ratio was higher in MIlg-SED when compared to the other groups. The infarcted trained animals presented diminished hypertrophy. The pulmonary water content was higher in MIlg-SED animals (81+/-0.4%) than in C-SED animals (79+/-0.4%). No differences were found for the other comparisons (C-TR: 79+/-0.4%; MImod-SED: 80+/-0.3%; MImod-TR: 80+/-0.6%; MIlg-TR: 79+/-0.7%).nnnCONCLUSIONnThe increase of cardiac mass and pulmonary water content presented by MIlg-SED was diminished in the trained animals. The results suggest that the practice of physical exercise can diminish HF and contribute to favorable cardiac remodeling.

A routine electrocardiogram cannot be used to determine the size of myocardial infarction in the rat

Nine lead electrocardiograms of non-infarcted (N = 61) and infarcted (N = 71) female Wistar rats (200-250 g) were analyzed in order to distinguish left ventricle myocardial infarction (MI) larger than 40% (LMI) from MI smaller than 40% (SMI). MI larger than 40% clearly caused a deviation of AQRS and AT from normal values of 270-360 degrees to 90-270 degrees. Infarcted rats showed Q wave in D1 larger than 1 mm with 94% sensitivity and 100% specificity. The sum of QRS positivity in V1, V2 and V6 lower than 10 mm identified MI with 82% sensitivity and 100% specificity. The data showed that MI can be easily and reliably diagnosed by electrocardiogram in the rat. However, contradicting what is frequently believed, when specificity and sensitivity were analyzed focusing on MI size, none of these current electrocardiographic indices of MI size adequately discriminates LMI from SMI.

The effect of low-level laser therapy on oxidative stress and functional fitness in aged rats subjected to swimming: an aerobic exercise.

The aim of the present study was to determine whether low-level laser therapy (LLLT) in conjunction with aerobic training interferes with oxidative stress, thereby influencing the performance of old rats participating in swimming. Thirty Wistar rats (Norvegicus albinus) (24 aged and six young) were tested. The older animals were randomly divided into aged-control, aged-exercise, aged-LLLT, aged-LLLT/exercise, and young-control. Aerobic capacity (VO2max0.75) was analyzed before and after the training period. The exercise groups were trained for 6xa0weeks, and the LLLT was applied at 808xa0nm and 4xa0J energy. The rats were euthanized, and muscle tissue was collected to analyze the index of lipid peroxidation thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities. VO20.75max values in the aged-LLLT/exercise group were significantly higher from those in the baseline older group (p <0.01) and the LLLT and exercise group (p <0.05). The results indicate that the activities of CAT, SOD, and GPx were higher and statistically significant (p <0.05) in the LLLT/exercise group than those in the LLLT and exercise groups. Young animals presented lesser and statistically significant activities of antioxidant enzymes compared to the aged group. The LLLT/exercise group and the LLLT and exercise group could also mitigate the concentration of TBARS (pu2009>u20090.05). Laser therapy in conjunction with aerobic training may reduce oxidative stress, as well as increase VO2 0.75max, indicating that an aerobic exercise such as swimming increases speed and improves performance in aged animals treated with LLLT.

Cardiac implications after myocardial infarction in rats previously undergoing physical exercise.

BACKGROUNDnFew studies have analyzed the cardiac effects of exercise prior to coronary occlusion.nnnOBJECTIVEnTo evaluate the effects of myocardial infarction in rats undergoing physical exercise.nnnMETHODSnFemale rats underwent swimming exercise or were kept sedentary for eight weeks and were randomized to coronary occlusion or sham surgery, in one of the following four groups: Sedentary (S), exercise (E), Sedentary myocardial infarction (SMI) and Exercise myocardial infarction (EMI). After six weeks, their biometrics, Doppler echocardiography, hemodynamics and myocardial mechanics were analyzed.nnnRESULTSnNo cardioprotection was observed in EMI animals and there was no difference in infarct size (%LV) between EMI (38.50 ± 4.60%) and SMI (36.58 ± 4.11%). Water content of the lung (%) of SMI (80 ± 0.59) and EMI (80 ± 0.57) was higher than that of S (78 ± 0.15) and E (78 ± 0.57) groups. Left ventricular systolic pressure (mmHg) (S: 130 ± 5, E: 118 ± 8; SMI: 91 ± 3; EMI: 98 ± 3) and the first positive time derivative (mmHg) positive pressure (S: 8216 ± 385; E: 8437 ± 572; SMI: 4674 ± 455; EMI: 5080 ± 412) of S and E were higher than those of SMI and EMI. The transverse fractional shortening (%) of SMI (27 ± 2) and EMI (25 ± 2) were similar and lower than that of E (65 ± 2) and S (69 ± 2). The E/A ratio was higher in SMI (5.14 ± 0.61) and EMI (4.73 ± 0.57) compared to S (2.96 ± 0.24) and E (2.83 ± 0 21). In studies of isolated papillary muscle, depression of the contractile capacity observed was similar to that of SMI and EMI, and there was no change in myocardial stiffness.nnnCONCLUSIONnPrevious training by swimming did not attenuate cardiac implications due to myocardial infarction.

Exercise Training Attenuates Right Ventricular Remodeling in Rats with Pulmonary Arterial Stenosis

Introduction: Pulmonary arterial stenosis (PAS) is a congenital defect that causes outflow tract obstruction of the right ventricle (RV). Currently, negative issues are reported in the PAS management: not all patients may be eligible to surgeries; there is often the need for another surgery during passage to adulthood; patients with mild stenosis may have later cardiac adverse repercussions. Thus, the search for approaches to counteract the long-term PAS effects showed to be a current target. At the study herein, we evaluated the cardioprotective role of exercise training in rats submitted to PAS for 9 weeks. Methods and Results: Exercise resulted in improved physical fitness and systolic RV function. Exercise also blunted concentric cavity changes, diastolic dysfunction, and fibrosis induced by PAS. Exercise additional benefits were also reported in a pro-survival signal, in which there were increased Akt1 activity and normalized myocardial apoptosis. These findings were accompanied by microRNA-1 downregulation and microRNA-21 upregulation. Moreover, exercise was associated with a higher myocardial abundance of the sarcomeric protein α-MHC and proteins that modulate calcium handling—ryanodine receptor and Serca 2, supporting the potential role of exercise in improving myocardial performance. Conclusion: Our results represent the first demonstration that exercise can attenuate the RV remodeling in an experimental PAS. The cardioprotective effects were associated with positive modulation of RV function, survival signaling pathway, apoptosis, and proteins involved in the regulation of myocardial contractility.

Incidence of heart failure in infarcted rats that die spontaneously

The present study reports for the first time the incidence of congestive heart failure (CHF) in previously infarcted rats that died spontaneously. Previously, pulmonary (PWC) and hepatic (HWC) water contents were determined in normal rats: 14 control animals were evaluated immediately after sacrifice, 8 placed in a refrigerator for 24 h, and 10 left at room temperature for 24 h. In the infarcted group, 9 rats died before (acute) and 28 died 48 h after (chronic) myocardial infarction. Thirteen chronic animals were submitted only to autopsy (N = 13), whereas PWC and HWC were also determined in the others (N = 15). Seven rats survived 48 h and died during anesthesia. Notably, PWC differed in normal rats: ambient (75.7 +/- 1.3%) < control (77.5 +/- 0.7%) < refrigerator (79.1 +/- 1.4%) and there were no differences with respect to HWC. No clinical signs of CHF (dyspnea, lethargy or foot edema) were observed in infarcted rats before death. PWC was elevated in all chronic and anesthetized rats. HWC was increased in 48% of chronic and in all anesthetized rats. Our data showed that PWC needs to be evaluated before 24 h post mortem and that CHF is the rule in chronic infarcted rats suffering natural death. The congestive syndrome cannot be diagnosed correctly in rats by clinical signs alone, as previously proposed.

Effect Of Resistance Training On Myocardial Contractility In Vitro After Sleep Deprivation

Fundamento: O treinamento resistido promove beneficios a saude cardiovascular, a qual e influenciada pela privacao de sono. Objetivo: Investigar o efeito previo do treinamento resistido de alta intensidade sobre a contratilidade miocardica de ratos privados de sono paradoxal. Metodos: Quarenta ratos machos Wistar foram distribuidos nos grupos controle (CTRL), treinamento resistido (TRES), privacao de sono paradoxal por 96 horas (PSP96) e treinamento resistido seguido de privacao de sono paradoxal por 96 horas (TRES/PSP96). O treinamento resistido foi de alta intensidade, por 8 semanas, 5x/semana. Vinte e quatro horas apos a ultima sessao de treinamento, os grupos PSP96 e TRES/PSP96 foram submetidos ao protocolo de privacao de sono paradoxal e em seguida foi realizado o estudo in vitro da mecânica contratil do musculo papilar isolado. Resultados: Em comparacao ao CTRL, os grupos PSP96 e TRES/PSP96 apresentaram menor comprimento do musculo papilar e aumento da area de seccao transversa. Associado a essas alteracoes, verificou-se a diminuicao das derivadas temporais da forca na contracao e relaxamento em todas as condicoes avaliadas. Somente o grupo PSP96 apresentou reducao da tensao de repouso e lentidao no tempo de relaxamento, sendo este ultimo atenuado pelo treinamento resistido previo. Conclusao: O treinamento resistido previo a PSP foi parcialmente protetor contra as alteracoes contrateis do musculo papilar, minimizando a lentidao no tempo de relaxamento. Assim, o carater de alta intensidade do protocolo adotado parece nao proteger plenamente o tecido cardiaco frente a PSP.