Exercise training prior to myocardial infarction attenuates cardiac deterioration and cardiomyocyte dysfunction in rats

Abstract

OBJECTIVES:The present study was performed to investigate 1) whether aerobic exercise training prior to myocardial infarction would prevent cardiac dysfunction and structural deterioration and 2) whether the potential cardiac benefits of aerobic exercise training would be associated with preserved morphological and contractile properties of cardiomyocytes in post-infarct remodeled myocardium.METHODS:Male Wistar rats underwent an aerobic exercise training protocol for eight weeks. The rats were then assigned to sham surgery (SHAM), sedentary lifestyle and myocardial infarction or exercise training and myocardial infarction groups and were evaluated 15 days after the surgery. Left ventricular tissue was analyzed histologically, and the contractile function of isolated myocytes was measured. Student's t-test was used to analyze infarct size and ventricular wall thickness, and the other parameters were analyzed by the Kruskal-Wallis test followed by Dunn's test or a one-way analysis of variance followed by Tukey's test (p<0.05).RESULTS:Myocardial infarctions in exercise-trained animals resulted in a smaller myocardial infarction extension, a thicker infarcted wall and less collagen accumulation as compared to myocardial infarctions in sedentary animals. Myocardial infarction-induced left ventricular dilation and cardiac dysfunction, as evaluated by +dP/dt and -dP/dt, were both prevented by previous aerobic exercise training. Moreover, aerobic exercise training preserved cardiac myocyte shortening, improved the maximum shortening and relengthening velocities in infarcted hearts and enhanced responsiveness to calcium.CONCLUSION:Previous aerobic exercise training attenuated the cardiac dysfunction and structural deterioration promoted by myocardial infarction, and such benefits were associated with preserved cardiomyocyte morphological and contractile properties.

Preventive aerobic training exerts a cardioprotective effect on rats treated with monocrotaline

“…Aerobic exercise is a non-pharmacological and effective way to protect the heart against aggression and insult (Portes & Tucci 2006); however, there are studies that found no benefits to this condition (Veiga et al 2011(Veiga et al , 2013. The preventive training protocols for acute myocardial infarction were performed for an average of 8 weeks, which was the period used in the present study (Freimann et al 2005;Bozi et al 2013;Veiga et al 2013).…”

“…However, studies suggest that chronic aerobic physical training applied in a preventive manner in acute myocardial infarction promoted improvement in cardiac function and survival (Waard & Duncker ; Bozi et al . ).…”

“…The beneficial effects of chronic aerobic physical exercise on RV remodelling in animals with PAH induced by monocrotaline have been described (Handoko et al 2009;Colombo et al 2013); but a literature search did not reveal any studies which assessed the effects that preventive aerobic training exerts on RV remodelling induced by PAH. However, studies suggest that chronic aerobic physical training applied in a preventive manner in acute myocardial infarction promoted improvement in cardiac function and survival (Waard & Duncker 2009;Bozi et al 2013).…”

Exercise attenuates inflammation and limits scar thinning after myocardial infarction in mice

“…In contrast, a recent study (72) failed to confirm the benefits of exercise-based rehabilitation. Besides the investigation of therapeutic effects of exercise on the remodeling process after MI, more recently, researchers have become interested in the effect of endurance training before MI and reported protective but also neutral effects (5,7,12,70,75).…”

The Beneficial Role of Exercise Training for Myocardial Infarction Treatment in Elderly

“…In one study with animals, exercise pretreatment preserved cardiomyocyte contractile and morphological properties, which played a crucial role in cardioprotection against cardiac structural deterioration and dysfunction caused by MI (Bozi et al, 2013). Exercise pretreatment could also reduce collagen accumulation, thicken infarcted wall, alleviate MI volume, improve muscle strength, enhance responsiveness to calcium, and preserve cardiac myocyte shortening; it could also improve the maximum relengthening and shortening velocities in infarcted hearts of rats (Bozi et al, 2013;Ciolac et al, 2014). There was a close relationship between cardio protection against myocardial injury induced by exercise pretreatment and cardiac natriuretic peptide receptor B (NPR-B) and C-type natriuretic peptide (CNP) (Lu and Pan, 2017).…”