Abstract:

Objective To explore the methods of acute exhaustive exercise in mice and rats, and investigate the effects of acute exhaustive exercise on myocardium ultrastructures. Methods Ten healthy C57/black mice and 10 healthy SD rats aged 8 months were divided into control group and exhaustive exercise group respectively. Before acute exhaustive exercise, mice were subjected to adaptive training (treadmill running, 1 time/d, 10 min/time, 15 to 20 m/min) for 2 weeks, and SD rats received adaptive training (treadmill running, 1 time/d, 15 min/time, 20 m/min) for 1 week. Animals in exhaustive exercise group underwent exhaustive running for one time (20 to 25 m/min for mice and 25 to 30 m/min for rats) until they stubbornly refused to exercise with signs of exhaustion. Left ventricular muscles were then obtained for ultrastructure observations with transmission electron microscope. Results After adaptive training in mice for 2 weeks, exhaustion occurred after continuous running for (4 561±2 174) m within (3.6±2.2) h, and the ultrastructures were characterized by myocardial edema, mitochondria cristae swelling and lysis, abnormal high density structures in some mitochondria and increased lysosomes. After adaptive training in rats for 1 week, exhaustion occurred after continuous running for (6 947±1 052) m within (2.3±0.4) h, and the ultrastructures were characterized by myocardial edema, chaotic myofilament arrangement, increased mitochondria density and mitochondria cristae rupture, lysis and vacuolization. Conclusion Acute exhaustive exercise can induce myocardial edema and mitochondrial damage in mice and rats.

Key words: acute exhaustive exercise, myocardium, ultrastructure, mitochondria, mouse, rat