Mechanism of myocardial oxidative damage in a rat model of one-time exhaustive exercise / 中国组织工程研究

ABSTRACT

BACKGROUND: Exhaustive exercise is a vigorous physical activity performed by an organism beyond its physiological limits, and it causes a series of histological changes in the body. Myocardial exercise-induced oxidative stress injury means that the organism generates free radicals through oxidative stress signal pathway to damage myocardial cells under exhaustive exercise. OBJECTIVE: To explore the mechanism of oxidative stress injury in rat myocardium caused by one-time exhaustive exercise based on the protein kinase C (PKC)/ NOX pathway. METHODS: Thirty adult male Sprague-Dawley rats were randomly divided into a control group, an exhaustive exercise group, and an exhaustive exercise+drug group, with 10 rats in each group. The exhaustive exercise+drug group was injected with PKC inhibitor chelerythrine (5 mg/kg body weight) for 3 consecutive days. Rats in the two exercise groups exercised at a speed of 25 m/min on a 0° incline treadmill until exhaustion. Immediately after exercise, blood sample was collected from each rat, and then the rat’s left ventricle was removed for hematoxylin-eosin staining to observe the morphological changes of myocardial cells. Serum and myocardial malondialdehyde and myocardial reactive oxygen species levels were detected. The protein expressions of PKC, NOX2, NOX4 and 3-NT in rat myocardial tissue were determined by western blot. RESULTS AND CONCLUSION: The myocardial tissues in the exhaustive exercise and exhaustive exercise+drug groups were damaged, but the damage was significantly eased in the exhaustive exercise+drug group compared with the exhaustive exercise group. Compared with the control group, the reactive oxygen species level in the myocardial tissue of the exhaustive exercise group increased significantly (P < 0.05). Compared with the control group, the content of malondialdehyde in the myocardial tissues of the exhaustive exercise and exhaustive exercise+drug groups was significantly increased (P < 0.01), and the concentration of serum malondialdehyde in the exhaustive exercise group was significantly increased (P < 0.05). Compared with the control group, the expression levels of PKC, NOX2, NOX4 and 3-NT proteins in the myocardium of rats after exhaustive exercise were significantly increased (P < 0.01). Compared with the exhaustive exercise group, the expression levels of NOX2 and NOX4 in the myocardial tissue of rats significantly decreased in the exhaustive exercise+drug group (P < 0.01), and the expression of 3-NT significantly decreased (P < 0.05). Therefore, one-time exhaustive exercise can activate PKC and increase its protein expression in rat myocardial cells, which in turn induces an increase in the expression of NOX2 and NOX4 proteins in the myocardium, catalyzes the generation of large amounts of reactive oxygen species, and leads to the excessive production of peroxynitrite anions, thereby causing oxidative damage to the myocardium.