Intermittent hypoxia can improve myocardial energy metabolism / 中华物理医学与康复杂志

ABSTRACT

Objective:To explore any effect of intermittent hypoxia (IH) on myocardial energy metabolism and its mechanism.Methods:Twenty-one male Sprague-Dawley rats were randomly divided into a sham operation group, a myocardial infarction group and an observation group. The latter two groups received occlusion of the left anterior descending coronary artery. The observation group then lived in an hypoxic environment intermittently for 4 hours/day, 5 days/week for four weeks, while the other 2 groups were exposed to a normal level of oxygen. The ejection fraction of the left ventricle (LVEF) was measured at 1 week after the modeling and 4 weeks after the start of the intervention. Also at that point myocardial fibrosis, mitochondrial structure, ATP content, and the protein expressions of adenosine monophosphate-activated protein kinase alpha1 (AMPKα1) and sirtuins protein family member 3 (SIRT3) were assessed in all three groups.Results:A significant decrease in the LVEF, the number of mitochondria, ATP content, AMPKα1 and SIRT3 protein were observed in the infarction group compared with the sham group. There was also a significant increase in the myocardial fibrosis index. Moreover, the LVEF decreased significantly and the myocardial fibrosis index had increased significantly in the observation group compared with the sham operation group, though the two groups exhibited no significant differences the number of mitochondria, ATP content, or the expression of AMPKα1 or SIRT3. Compared with the myocardial infarction group, in the observation group there was a significant increase in the LVEF, the number of mitochondria, ATP content, and the expression of AMPKα1 and SIRT3 protein, with a significant decrease in the fibrosis index. AMPKα1 and SIRT3 level were positively inter-correlated and positively correlated with LVEF and ATP content.Conclusions:IH intervention can promote ATP synthesis and improve mitochondrial structure by regulating the AMPKα1/SIRT3 pathway, reducing myocardial fibrosis and enhancing cardiac function.