Aerobic Training Is Better Than Resistance Training on Cardiac Function and Autonomic Modulation in Female ob/ob Mice.

Objective: This study evaluated the effects of aerobic, resistance, and combined exercise training on cardiac function and autonomic modulation in female ob/ob mice. Methods: Four-week-old female wild type and obese (ob/ob) mice were divided into five groups (n = 8): control (WT), obese (OB) obese + aerobic training (OBA), obese + resistance training (OBR), and obese + combined training (OBC). The exercise training was performed on treadmill and/or ladder at 40-60% maximum test during 8 weeks. Cardiac function was measured using echo machine. Heart rate variability (HRV) was evaluated in the time and frequency domain. Results: OB group presented higher body weight gain (~600%), glycemia (~44%) and glucose intolerance (~150%), reduction of cardiac vagal modulation, evidenced by a lower RMMSD (~56%), total power and high frequency band, and a higher isovolumic relaxation time (IVRT) (~24%) in relation to the WT group. Aerobic and combined training led to a lower IVRT (OBA: ~14%; OBC: ~14%) and myocardial global index (OBA: ~37%; OBC: ~44%). The OBA group presented an increased in vagal indexes of HRV than the other ob/ob groups. A negative correlation was observed between the delta of aerobic exercise capacity and MPI (r = 0.45; p = 0.002) and exercise capacity and body weight gain (r = 0.39; p = 0.002). Conclusion: Only the obese females underwent to aerobic exercise training showed improvement in cardiac function and HRV. Moreover, the aerobic exercise capacity as well as a greater responsivity to aerobic exercise training is intimately associated with these improvements, reinforcing the importance of aerobic exercise training to this population.

Influência dos hormônios sexuais no consumo de oxigênio de ratos / Influence of sexual hormones on oxygen consumption in rats / Influencia de las hormonas sexuales en el consumo de oxígeno en ratas

Introdução: Achados da literatura sugerem que oscilações dos hormônios sexuais femininos podem alterar o consumo máximo de oxigênio (VO2max). Objetivo: Comparar o VO2max entre ratos machos (M, n=8), fêmeas nas fases ovulatórias (OV, n=8) ou não-ovulatórias (NOV, n=8) do ciclo estral e ooforectomizadas (OS, n=8). Métodos: A avaliação do consumo de oxigênio foi realizada em esteira rolante com caixa metabólica acoplada. Resultados: Em repouso, o VO2 foi semelhante entre os grupos estudados. O grupo M apresentou maior VO2max em relação ao grupo NOV, mas valores semelhantes ao do grupo OV. O VO2max foi menor no grupo ooforectomizado (OS: 62±3 ml.kg-1.min-1) quando comparado aos demais grupos (M: 92±2; NOV: 77±4; OV: 87±3 ml.kg-1.min-1). Conclusões: Esses achados evidenciam que a variação hormonal decorrente das diferentes fases do ciclo estral e da privação dos hormônios ovarianos pode induzir alterações no consumo máximo de oxigênio em ratos. .

Introduction: Literature findings suggest that fluctuations of female sex hormones may change the maximum oxygen consumption (VO2 max). Objective: To compare the VO2 max among male rats (M, n = 8), female rats on ovulatory (OV, n=8) or non-ovulatory (NOV, n=8) phases of the estrous cycle and ovariectomized (OS, n=8). Methods: The evaluation of oxygen consumption was performed on a treadmill coupled with metabolic box. Results: At rest VO2 was similar among groups. The M group had a higher VO2 max compared to the NOV group, however showed similar values when compared to OV group. The VO2 max was lower in the ovariectomized group (OS: 62±3 ml.kg-1.min-1) compared to other groups (M: 92±2; NOV: 77 ± 4; OV: 87 ± 3 ml.kg-1.min-1). Conclusions: These findings suggest that hormonal variation resulting from different phases of the estrous cycle and ovarian hormone deprivation can induce changes in maximal oxygen uptake in rats. .

Introducción: Hallazgos de la literatura sugieren que oscilaciones de las hormonas sexuales femeninas pueden alterar el consumo máximo de oxígeno (VO2max). Objetivo: Comparar el VO2max entre ratas machos (M, n=8), hembras en las fases ovulatorias (OV, n=8) o no ovulatorias (NOV, n=8) del ciclo estral y ooforectomizadas (OS, n=8). Métodos: La evaluación del consumo de oxígeno fue realizada en cinta rodante con caja metabólica acoplada. Resultados: En reposo, el VO2 fue semejante entre los grupos estudiados. El grupo M presentó mayor VO2max en relación al grupo NOV, pero valores semejantes a los del grupo OV. El VO2max fue menor en el grupo ooforectomizado (OS: 62±3 ml.kg-1.min-1) cuando comparado a los demás grupos (MS: 92±2; NOV: 77±4; OV: 87±3 ml.kg-1.min-1). Conclusiones: Esos hallazgos evidencian que la variación hormonal proveniente de las diferentes fases del ciclo estral y de la privación de las hormonas ováricas puede inducir alteraciones en el consumo máximo de oxígeno en ratas. .

Resistance training after myocardial infarction in rats: its role on cardiac and autonomic function.

BACKGROUND: Although resistance exercise training is part of cardiovascular rehabilitation programs, little is known about its role on the cardiac and autonomic function after myocardial infarction. OBJECTIVE: To evaluate the effects of resistance exercise training, started early after myocardial infarction, on cardiac function, hemodynamic profile, and autonomic modulation in rats. METHODS: Male Wistar rats were divided into four groups: sedentary control, trained control, sedentary infarcted and trained infarcted rats. Each group with n = 9 rats. The animals underwent maximum load test and echocardiography at the beginning and at the end of the resistance exercise training (in an adapted ladder, 40% to 60% of the maximum load test, 3 months, 5 days/week). At the end, hemodynamic, baroreflex sensitivity and autonomic modulation assessments were made. RESULTS: The maximum load test increased in groups trained control (+32%) and trained infarcted (+46%) in relation to groups sedentary control and sedentary infarcted. Although no change occurred regarding the myocardial infarction size and systolic function, the E/A ratio (-23%), myocardial performance index (-39%) and systolic blood pressure (+6%) improved with resistance exercise training in group trained infarcted. Concomitantly, the training provided additional benefits in the high frequency bands of the pulse interval (+45%), as well as in the low frequency band of systolic blood pressure (-46%) in rats from group trained infarcted in relation to group sedentary infarcted. CONCLUSION: Resistance exercise training alone may be an important and safe tool in the management of patients after myocardial infarction, considering that it does not lead to significant changes in the ventricular function, reduces the global cardiac stress, and significantly improves the vascular and cardiac autonomic modulation in infarcted rats.

Resistance Training After Myocardial Infarction in Rats: Its Role on Cardiac and Autonomic Function / Treinamento Resistido Após Infarto do Miocárdio em Ratos: Papel na Função Cardíaca e Autonômica

Background: Although resistance exercise training is part of cardiovascular rehabilitation programs, little is known about its role on the cardiac and autonomic function after myocardial infarction. Objective: To evaluate the effects of resistance exercise training, started early after myocardial infarction, on cardiac function, hemodynamic profile, and autonomic modulation in rats. Methods: Male Wistar rats were divided into four groups: sedentary control, trained control, sedentary infarcted and trained infarcted rats. Each group with n = 9 rats. The animals underwent maximum load test and echocardiography at the beginning and at the end of the resistance exercise training (in an adapted ladder, 40% to 60% of the maximum load test, 3 months, 5 days/week). At the end, hemodynamic, baroreflex sensitivity and autonomic modulation assessments were made. Results: The maximum load test increased in groups trained control (+32%) and trained infarcted (+46%) in relation to groups sedentary control and sedentary infarcted. Although no change occurred regarding the myocardial infarction size and systolic function, the E/A ratio (-23%), myocardial performance index (-39%) and systolic blood pressure (+6%) improved with resistance exercise training in group trained infarcted. Concomitantly, the training provided additional benefits in the high frequency bands of the pulse interval (+45%), as well as in the low frequency band of systolic blood pressure (-46%) in rats from group trained infarcted in relation to group sedentary infarcted. Conclusion: Resistance exercise training alone may be an important and safe tool in the management of patients after myocardial infarction, considering that it does not lead to significant changes in the ventricular function, reduces the global cardiac stress, and significantly improves the vascular and cardiac autonomic modulation in infarcted rats. .

Fundamento: Embora o treinamento físico resistido esteja inserido nos programas de reabilitação cardiovascular, pouco se sabe sobre seu papel isolado na função cardíaca e autonômica após o infarto do miocárdio. Objetivo: Avaliar os efeitos do treinamento físico resistido iniciado precocemente após o infarto do miocárdio na função cardíaca, no perfil hemodinâmico e na modulação autonômica de ratos. Métodos: Ratos Wistar machos foram divididos em Grupos Controle Sedentário, Controle Treinado, Infartado Sedentário e Infartado Treinado. Cada grupo foi composto por 9 ratos. Os animais realizaram o teste de carga máxima e a ecocardiografia ao início e ao final do treinamento físico resistido (em escada adaptada, 40 a 60% do teste de carga máxima, 3 meses, 5 dias/semana). Ao final, foram realizadas avaliações hemodinâmicas, de sensibilidade barorreflexa e da modulação autonômica. Resultados: O teste de carga máxima aumentou nos Grupos Controle Treinado (+32%) e Infartado Treinado (+46%) em relação aos Grupos Controle Sedentário e Infartado Sedentário. Embora a área de infarto do miocárdio e a função sistólica não tenham sido alteradas, a relação E/A (-23%), o índice de desempenho miocárdico (-39%) e a pressão arterial sistólica (+6%) foram melhorados pelo treinamento físico resistido no Grupo Infartado Treinado. Paralelamente, o treinamento induziu os grupos a benefícios adicionais nas bandas de alta frequência do intervalo de pulso (+45%), bem como a banda de baixa frequência da pressão arterial sistólica (-46%) nos ratos do Grupo Infartado Treinado em relação aos do Infartado Sedentário. Conclusão: O treinamento físico resistido dinâmico ...

Short-term diabetes attenuates left ventricular dysfunction and mortality rates after myocardial infarction in rodents.

OBJECTIVES: To investigate the effects of hyperglycemia on left ventricular dysfunction, morphometry, myocardial infarction area, hemodynamic parameters, oxidative stress profile, and mortality rate in rats that had undergone seven days of myocardial infarction. INTRODUCTION: Previous research has demonstrated that hyperglycemia may protect the heart against ischemic injury. METHODS: Male Wistar rats were divided into four groups: control-sham, diabetes-sham, myocardial infarction, and diabetes + myocardial infarction. Myocardial infarction was induced 14 days after diabetes induction. Ventricular function and morphometry, as well as oxidative stress and hemodynamic parameters, were evaluated after seven days of myocardial infarction. RESULTS: The myocardial infarction area, which was similar in the infarcted groups at the initial evaluation, was reduced in the diabetes + myocardial infarction animals (23 ± 3%) when compared with the myocardial infarction (42 ± 7%, p < 0.001) animals at the final evaluation. The ejection fraction (22%, p = 0.003), velocity of circumferential fiber shortening (30%, p = 0.001), and left ventricular isovolumetric relaxation time (26%, p = 0.002) were increased in the diabetes + myocardial infarction group compared with the myocardial infarction group. The diabetes-sham and diabetes + myocardial infarction groups displayed increased catalase concentrations compared to the control-sham and myocardial infarction groups (diabetes-sham: 32 ± 3; diabetes + myocardial infarction: 35 ± 0.7; control-sham: 12 ± 2; myocardial infarction: 16 ± 0.1 pmol min⁻¹ mg⁻¹ protein). The levels of thiobarbituric acid-reactive substances were reduced in the diabetes-sham rats compared to the control-sham rats. These positive adaptations were reflected in a reduced mortality rate in the diabetes + myocardial infarction animals (18.5%) compared with the myocardial infarction animals (40.7%, p = 0.001). CONCLUSIONS: These data suggest that short-term hyperglycemia initiates compensatory mechanisms, as demonstrated by increased catalase levels, which culminate in improvements in the ventricular response, infarcted area, and mortality rate in diabetic rats exposed to ischemic injury.

Short-term diabetes attenuates left ventricular dysfunction and mortality rates after myocardial infarction in rodents

OBJECTIVES: To investigate the effects of hyperglycemia on left ventricular dysfunction, morphometry, myocardial infarction area, hemodynamic parameters, oxidative stress profile, and mortality rate in rats that had undergone seven days of myocardial infarction. INTRODUCTION: Previous research has demonstrated that hyperglycemia may protect the heart against ischemic injury. METHODS: Male Wistar rats were divided into four groups: control-sham, diabetes-sham, myocardial infarction, and diabetes + myocardial infarction. Myocardial infarction was induced 14 days after diabetes induction. Ventricular function and morphometry, as well as oxidative stress and hemodynamic parameters, were evaluated after seven days of myocardial infarction. RESULTS: The myocardial infarction area, which was similar in the infarcted groups at the initial evaluation, was reduced in the diabetes + myocardial infarction animals (23 ± 3 percent) when compared with the myocardial infarction (42 ± 7 percent, p<0.001) animals at the final evaluation. The ejection fraction (22 percent, p = 0.003), velocity of circumferential fiber shortening (30 percent, p = 0.001), and left ventricular isovolumetric relaxation time (26 percent, p = 0.002) were increased in the diabetes + myocardial infarction group compared with the myocardial infarction group. The diabetes-sham and diabetes + myocardial infarction groups displayed increased catalase concentrations compared to the control-sham and myocardial infarction groups (diabetes-sham: 32± 3; diabetes + myocardial infarction: 35± 0.7; control-sham: 12 ± 2; myocardial infarction: 16 ± 0.1 pmol min-1 mg-1 protein). The levels of thiobarbituric acid-reactive substances were reduced in the diabetes-sham rats compared to the control-sham rats. These positive adaptations were reflected in a reduced mortality rate in the diabetes + myocardial infarction animals (18.5 percent) compared with the myocardial infarction animals (40.7 percent, p = 0.001). CONCLUSIONS: These data suggest that short-term hyperglycemia initiates compensatory mechanisms, as demonstrated by increased catalase levels, which culminate in improvements in the ventricular response, infarcted area, and mortality rate in diabetic rats exposed to ischemic injury.