Effects of late aerobic exercise on cardiac remodeling of rats with small myocardial infarction

Abstract

Background Physical exercise has been highlighted as an important non-pharmacological therapy for prevention and treatment of several cardiovascular diseases. However, its effects on hearts with minor cardiac remodeling are not clear. Purpose To evaluate the influence of aerobic physical exercise on functional capacity, cardiac structure, left ventricular (LV) function, and gene expression of NADPH oxidase subunits in rats with small-sized myocardial infarction (MI). Methods Three months after MI induction, Wistar rats were divided into three groups: Sham; sedentary MI (MI-SED); and aerobic exercised MI (MI-EA). Rats exercised three times a week for 12 weeks on a treadmill. Echocardiogram was performed before and after experimental period. Infarction size and cardiomyocyte diameters were evaluated by histology. Gene expression was assessed by RT-PCR. Results Only rats with MI size lower than 30% of LV total area were included in the study. Functional capacity was higher in MI-AE than the other groups. Infarction size did not differ between groups. Infarcted rats had increased LV diastolic and systolic diameter, left atrial diameter, and LV mass, with systolic dysfunction. LV diastolic posterior wall thickness was higher in MI-AE than Sham, and relative wall thickness was lower in MI-SED than MI-AE and Sham groups. Cardiomyocyte diameter was smaller in infarcted groups than Sham. Myocardial gene expression of the NADPH oxidase subunits NOX2, NOX4, p22phox, and p47phox did not differ between groups. Conclusion Small-sized myocardial infarction changes cardiac structures and left ventricular systolic function. Late aerobic physical exercise improves functional capacity and cardiac remodeling by preserving left ventricular geometry. NADPH oxidase subunits gene expression is not involved in cardiac remodeling or modulated by aerobic exercise in rats with small myocardial infarction. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): CNPq; CAPES

The Role of Oxidative Stress in the Aging Heart

“…NOX activity may be enhanced by several stimuli, such as cyclic stretch, angiotensin II, α-adrenergic agonists, endothelin-1, and TNF-α, many of which are relevant to left ventricular hypertrophy and heart failure [ 98 ]. Studies have shown both increased and unchanged myocardial and skeletal muscle NOX activity during cardiac injury [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ]. Differences in experimental models and cardiac injury levels could be involved in the divergent results.…”

O Ano de 2021 na Pesquisa Básica: a Procura por Modelos Translacionais

“…A pesquisa básica e translacional tem focado nos mecanismos envolvidos nos efeitos benéficos do exercício. [9][10][11] Vários estudos mostraram que o exercício melhora a remodelação cardíaca induzida por infarto do miocárdio extenso. 12 Souza et al, 10 observaram que, também em situação de agressão cardíaca menos grave como no infarto do miocárdio pequeno, o exercício aeróbio em esteira, por 12 semanas, melhora a capacidade funcional e preserva a geometria ventricular esquerda.…”

“…[9][10][11] Vários estudos mostraram que o exercício melhora a remodelação cardíaca induzida por infarto do miocárdio extenso. 12 Souza et al, 10 observaram que, também em situação de agressão cardíaca menos grave como no infarto do miocárdio pequeno, o exercício aeróbio em esteira, por 12 semanas, melhora a capacidade funcional e preserva a geometria ventricular esquerda. Da mesma maneira, o exercício resultou em efeitos benéficos em ratos com hipertensão renovascular.…”

A Importância dos Programas de Exercícios Pós-Infarto

“…An article by Souza et al 13 analyzes the late effects of AT in late post-infarction in animal models. This represents yet another attempt to clarify this issue.…”

“…In an elegant, controlled study, Souza et al 13 induced myocardial infarction (MI) by ligating the left anterior descending coronary artery. Three months later, surviving rats were subjected to transthoracic ECHO and exercise testing, then were assigned to three groups: sham-operated animals were used as controls (Sham n=15); sedentary MI (MI-SED, n=22) and aerobic exercised MI (MI-AE, n=21) for three months.…”