Cardioprotection afforded by exercise training prior to myocardial infarction is associated with autonomic function improvement.

Fernando Rodrigues,Kátia De Angelis,Daniele Jardim Feriani,Marcos Elias Vergilino Abssamra,Leandro Yanase Rocha,Diego Figueroa,Catarina Andrade Barboza,Maria Cláudia Irigoyen,Bruno Rodrigues,Gabriel Inacio Honorato Souza,Nicolle Martins Carrozi,Cristiano Mostarda

doi:10.1186/1471-2261-14-84

Abstract

BackgroundIt has been suggested that exercise training (ET) protects against the pathological remodeling and ventricular dysfunction induced by myocardial infarction (MI). However, it remains unclear whether the positive adjustments on baroreflex and cardiac autonomic modulations promoted by ET may afford a cardioprotective mechanism. The aim of this study was to evaluate the effects of aerobic ET, prior to MI, on cardiac remodeling and function, as well as on baroreflex sensitivity and autonomic modulation in rats.MethodsMale Wistar rats were divided into 4 groups: sedentary rats submitted to Sham surgery (C); trained rats submitted to Sham surgery (TC); sedentary rats submitted to MI (I), trained rats submitted to MI (TI). Sham and MI were performed after ET period. After surgeries, echocardiographic, hemodynamic and autonomic (baroreflex sensitivity, cardiovascular autonomic modulation) evaluations were conducted.ResultsPrior ET prevented an additional decline in exercise capacity in TI group in comparison with I. MI area was not modified by previous ET. ET was able to increase the survival and prevent additional left ventricle dysfunction in TI rats. Although changes in hemodynamic evaluations were not observed, ET prevented the decrease of baroreflex sensitivity, and autonomic dysfunction in TI animals when compared with I animals. Importantly, cardiac improvement was associated with the prevention of cardiac autonomic impairment in studied groups.ConclusionsPrior ET was effective in changing aerobic capacity, left ventricular morphology and function in rats undergoing MI. Furthermore, these cardioprotective effects were associated with attenuated cardiac autonomic dysfunction observed in trained rats. Although these cause-effect relationships can only be inferred, rather than confirmed, our study suggests that positive adaptations of autonomic function by ET can play a vital role in preventing changes associated with cardiovascular disease, particularly in relation to MI.

Highlights

It has been suggested that exercise training (ET) protects against the pathological remodeling and ventricular dysfunction induced by myocardial infarction (MI)
The rats were randomly assigned to four groups: sedentary control rats submitted to Sham surgery (C, n = 8); trained control rats submitted to Sham surgery (TC, n = 8); sedentary rats submitted to MI surgery (I, n = 12), trained rats submitted to MI surgery (TI, n = 10)
Retroperitoneal adipose tissue weight was decreased in Trained Control Rats Submitted To Sham Surgery (TC) (2.4 ± 0.2 g) and TI (2.2 ± 0.2 g) rats when compared to C (5.2 ± 0.1 g) and I (4.9 ± 0.1 g) rats

Summary

Introduction

It has been suggested that exercise training (ET) protects against the pathological remodeling and ventricular dysfunction induced by myocardial infarction (MI). Despite distinct experimental designs and ET regimens, the data found in the literature suggest that ET protects against the pathological remodeling and ventricular dysfunction induced by MI in rodents [18,19,20,21,22,23] Mechanisms such as the formation of collateral vessels [24], elevation of heat shock proteins [25], increased myocardial expression of cyclooxygenase [26], antioxidant protection [21] as well as antiinflammatory role of exercise [27] have been implicated as triggers of cardioprotection. It remains unclear whether the positive adjustments on baroreflex and cardiac autonomic modulations promoted by ET may afford a cardioprotective mechanism

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