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Chang JC, Lien CF, Lee WS, Chang HR, Hsu YC, Luo YP, Jeng JR, Hsieh JC, Yang KT. Intermittent Hypoxia Prevents Myocardial Mitochondrial Ca 2+ Overload and Cell Death during Ischemia/Reperfusion: The Role of Reactive Oxygen Species. Cells 2019; 8:cells8060564. [PMID: 31181855 PMCID: PMC6627395 DOI: 10.3390/cells8060564] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/01/2019] [Accepted: 06/05/2019] [Indexed: 12/24/2022] Open
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 O2 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 H2O2- and I/R-induced cell death. Moreover, H2O2-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 H2O2- 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.
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Affiliation(s)
- Jui-Chih Chang
- Department of Surgery, Buddhist Tzu Chi General Hospital, Hualien 97002, Taiwan.
- School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
| | - Chih-Feng Lien
- Institute of Medical Sciences, Tzu Chi University, Hualien 97004, Taiwan.
| | - Wen-Sen Lee
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
| | - Huai-Ren Chang
- School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
- Division of Cardiology, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien 97002, Taiwan.
| | - Yu-Cheng Hsu
- Master Program in Medical Physiology, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
| | - Yu-Po Luo
- Department of Surgery, Buddhist Tzu Chi General Hospital, Hualien 97002, Taiwan.
| | - Jing-Ren Jeng
- School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
- Division of Cardiology, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien 97002, Taiwan.
| | - Jen-Che Hsieh
- School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
- Division of Cardiology, Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien 97002, Taiwan.
| | - Kun-Ta Yang
- Department of Physiology, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan.
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