1. Intermittent Hypoxia Prevents Myocardial Mitochondrial Ca2+ Overload and Cell Death during Ischemia/Reperfusion: The Role of Reactive Oxygen Species.
- Author
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Chang, Jui-Chih, Lien, Chih-Feng, Lee, Wen-Sen, Chang, Huai-Ren, Hsu, Yu-Cheng, Luo, Yu-Po, Jeng, Jing-Ren, Hsieh, Jen-Che, and Yang, Kun-Ta
- Subjects
CELL death ,MYOCARDIAL reperfusion ,REACTIVE oxygen species ,OXIDANT status ,CORONARY disease ,MITOCHONDRIAL membranes - Abstract
It has been documented that reactive oxygen species (ROS) contribute to oxidative stress, leading to diseases such as ischemic heart disease. Recently, increasing evidence has indicated that short-term intermittent hypoxia (IH), similar to ischemia preconditioning, could yield cardioprotection. However, the underlying mechanism for the IH-induced cardioprotective effect remains unclear. The aim of this study was to determine whether IH exposure can enhance antioxidant capacity, which contributes to cardioprotection against oxidative stress and ischemia/reperfusion (I/R) injury in cardiomyocytes. Primary rat neonatal cardiomyocytes were cultured in IH condition with an oscillating O
2 concentration between 20% and 5% every 30 min. An MTT assay was conducted to examine the cell viability. Annexin V-FITC and SYTOX green fluorescent intensity and caspase 3 activity were detected to analyze the cell death. Fluorescent images for DCFDA, Fura-2, Rhod-2, and TMRM were acquired to analyze the ROS, cytosol Ca2+ , mitochondrial Ca2+ , and mitochondrial membrane potential, respectively. RT-PCR, immunocytofluorescence staining, and antioxidant activity assay were conducted to detect the expression of antioxidant enzymes. Our results show that IH induced slight increases of O2 − · and protected cardiomyocytes against H2 O2 - and I/R-induced cell death. Moreover, H2 O2 -induced Ca2+ imbalance and mitochondrial membrane depolarization were attenuated by IH, which also reduced the I/R-induced Ca2+ overload. Furthermore, treatment with IH increased the expression of Cu/Zn SOD and Mn SOD, the total antioxidant capacity, and the activity of catalase. Blockade of the IH-increased ROS production abolished the protective effects of IH on the Ca2+ homeostasis and antioxidant defense capacity. Taken together, our findings suggest that IH protected the cardiomyocytes against H2 O2 - and I/R-induced oxidative stress and cell death through maintaining Ca2+ homeostasis as well as the mitochondrial membrane potential, and upregulation of antioxidant enzymes. [ABSTRACT FROM AUTHOR]- Published
- 2019
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