INFLUÊNCIA DO EXERCÍCIO FÍSICO INTERVALADO DE ALTA INTENSIDADE
SOBRE A CONTRATILIDADE E CINÉTICA DE CÁLCIO INTRACELULAR DE
RATOS OBESOS INDUZIDOS POR DIETA HIPERLIPÍDICA SATURADA
Name: MATHEUS CORTELETTI DOS SANTOS
Publication date: 01/11/2023
Examining board:
Name |
Role |
|---|---|
| ANDRE SOARES LEOPOLDO | Advisor |
Summary: 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.
