Influência do exercício físico intermitente de alta intensidade sobre a contratilidade e proteínas reguladoras do trânsito de cálcio cardíaco de ratos obesos induzidos por dieta hiperlipídica saturada

Abstract

Introduction: Obesity is a multifactorial and complex disease, characterized by excessive accumulation of body fat, which can lead to a reduction in quality and life expectancy, as well as causing a set of vascular and metabolic dysfunctions. Studies have indicated that obesity is associated with myocardial contractility dysfunction, and data from the literature have demonstrated that cardiac dysfunction resulting from obesity may be due to an imbalance in intracellular calcium (Ca +2 ) transit. Given the exponential growth of obesity worldwide, several treatment strategies for obesity are reported in the literature, including physical exercise. Within this context, physical exercise is an important non-pharmacological tool that is widely used, but the use of continuous aerobic exercise is more frequently observed. In this sense, data from the literature also show that high-intensity interval training (HIIT) has demonstrated important results in relation to reducing body adiposity, as well as reversing risk factors associated with obesity. However, no studies were found that investigated the effect of HIIT on intracellular Ca +2 kinetics. Objective: To investigate the effects of HIIT on myocardial contractility and intracellular Ca +2 kinetics in obese rats induced by a saturated high-fat diet. Methodology: Wistar rats (n=71), 30 days old, were initially randomized into two groups, and, after obesity was established, randomly re-allocated according to the absence and/or presence of HIIT treatment for 8 weeks. Thus, the composition of the groups was: C: Control (n=12); CTR: Trained Control (n=12); Ob: Obese (n=13) and ObTR: Trained Obese (n=10) The nutritional, metabolic, lipid and hormonal profiles were evaluated. Physical performance was assessed using the maximum oxygen consumption test (VO2 maximum). The histology of cardiac, adipose and skeletal tissues were determined by optical microscopy. Myocardial contractility and intracellular Ca +2 kinetics were analyzed in isolated cardiac myocytes. Results: HIIT reduces the area of visceral adipose tissue, increases cardiorespiratory condition analyzed by VO2 maximum, prevents the risk of insulin resistance and increases the diameter of gastrocnemius muscle fibers. Considering myocardial morphology and contractility, HIIT prevents LV interstitial fibrosis, improves functional parameters of cardiac contractility, and improves myofilament sensitivity to Ca +2 . However, no significant changes in body adiposity were observed, since the final body mass and adiposity index were similar between the groups. Conclusion: HIIT promotes improvement in cardiorespiratory parameters and physical performance, as well as reducing the area of visceral fat and preventing the risk of insulin resistance and LV interstitial fibrosis. However, HIIT was not able to reduce total body adiposity. In addition, HIIT was efficient in contractility, promoting physiological cardiac remodeling with improvement in contractile functional parameters and cytosolic Ca +2 release and reuptake processes.