Effect of swimming on ultrastructure of myocardial cell in ventriculus sinister of rat

【Objective】 To explore the effects of different loading swimming exercises on ultrastructure of myocardial cell of ventriculus sinister in rat,so as to provide some information for the changes of physiology and pathology by the exercise-induced injury and recuperation of cardiac muscle.【Methods】 SD rats were randomly divided into two groups: different loading exercise group and exhaustive exercise group.In the different loading exercise group,a 12-week low,moderate and high loading swimming model was carried out in rats.In the exhaustive exercise group,a single exhaustive swimming was carried out in rats.After exercises,rat's ventriculus sinisters were cut off,and treated with routine procedures of transmission electron microscopy before observing the ultrastructure of myocardial cell under transmission electron microscope.【Results】 For low loading swimming exercise rats,the myocardial cell of ventriculus sinister showed intact clear ultrastructure.For moderate loading swimming exercise rats,the length of sarcomere increased,the quantities and volumes of mitochondria increased,and their cristae were densely arranged.For high loading swimming exercise rats,the ultrastructure of myocardial cell was lightly destroyed,the length of sarcomere decreased,nuclear envelope invaginated,chromatin condensed,and the mitochondrion cristae became unclear.At the end of exhaustive swimming exercise,the nucleus and mitochondrion were heavily changed,and the length of sarcomere decreased.At 24 hours after exhaustive exercise,the ultrastructure of nucleus and mitochondria showed attenuated injury,and the length of sarcomere increased,but the myocardial fibrils were arranged in heavy disorder.【Conclusion】 High loading and exhaustive exercises could destroy the structure of myocardial cell of ventriculus sinister.