ABSTRACT
Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury. Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to investigate whether intermittent hypoxia could attenuate ischemia/reperfusion-induced apoptosis in cardiac myocytes and its potential mechanisms. Adult male Sprague-Dawley rats were exposed to hypoxia simulated 5000 m in a hypobaric chamber for 6 h/day, lasting 42 days. Normoxia group rats were kept under normoxic conditions. Isolated perfused hearts from both groups were subjected to 30 min of global ischemia followed by 60 min reperfusion. Incidence of apoptosis in cardiac myocytes was determined by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA agarose gel electrophoresis. Expressions of apoptosis related proteins, Bax and Bcl-2, in cytosolic and membrane fraction were detected by Western Blotting. After ischemia/reperfusion, enhanced recovery of cardiac function was observed in intermittent hypoxia hearts compared with normoxia group. Ischemia/reperfusion-induced apoptosis, as evidenced by TUNEL-positive nuclei and DNA fragmentation, was significantly reduced in intermittent hypoxia group compared with normoxia group. After ischemia/reperfusion, expression of Bax in both cytosolic and membrane fractions was decreased in intermittent hypoxia hearts compared with normoxia group. Although ischemia/reperfusion did not induce changes in the level of Bcl-2 expression in cytosolic fraction between intermittent hypoxia and normoxia groups, the expression of Bcl-2 in membrane fraction was upregulated in intermittent hypoxia group compared with normoxia group. These results indicated that the cardioprotection of intermittent hypoxia against ischemia/reperfusion injury appears to be in part due to reduce myocardial apoptosis. Intermittent hypoxia attenuated ischemia/reperfusion-induced apoptosis via increasing the ratio of Bcl-2/Bax, especially in membrane fraction.
Similar content being viewed by others
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
References
Powell FL, Garcia N . Physiological effects of intermittent hypoxia. High altitude Medicine & Biology 2000; 1(2):125–36.
Meerson FZ, Gomzakov OA, Shimkovich MV . Adaptation to high altitude hypoxia as a factor preventing development of myocardial ischemic necrosis. Am J Cardiol 1973; 31(1):30–4.
Zhong N, Zhang Y, Zhu HF, Wang JC, Fang QZ, Zhou ZN . Myocardial capillary angiogenesis and coronary flow in ischemia tolerance rat by adaptation to intermittent high altitude hypoxia. Acta Pharmacol Sin 2002; 23(4):305–10.
Meerson FZ, Ustinova EE, Orlova EH . Prevention and elimination of heart arrhythmias by adaptation to intermittent high altitude hypoxia. Clinic Cardiology 1987; 10(12):783–9.
Asemu G, Papousek F, Ostadal B, Kolar F . Adaptation to high altitude hypoxia protects the rat heart against ischemia-induced arrhythmias. Involvement of mitochondrial KATP channel. J Mol Cell Cardiol 1999; 31(10):1821–31.
Zhang Y, Zhong N, Zhu HF, Zhou ZN . Antiarrhythmic and antioxidative effects of intermittent hypoxia exposure on rat myocardium. Acta Physiol Sin 2002; 52(2):89–92.
Mohan RM, Golding S and Paterson DJ . Intermittent hypoxiaimproves atrial tolerance to subsequent anoxia and reduces stress protein expression. Acta Physiol Scand 2001; 172:89–95.
Milano Giuseppina, Corno AF, Lippa S, et al. Chronic and intermittent hypoxia induce different degrees of myocardial tolerance to hypoxia-induced dysfunction. Exp Biol Med (Maywood) 2002; 227(6):389–97.
Zhong N, Zhang, Y Fang QZ, Zhou ZN . Intermittent hypoxia exposure-induced hear-shock protein 70 expression increases resistance of rat heart to ischemic injury. Acta Pharmacol Sin 2000; 21(5):467–72.
Zhang Y, Zhong N, Zhou ZN . Effects of intermittent hypoxia on action potential and contraction in non-ischemic and ischemic rat papillary muscle. Life Sciences 2000; 67(20):2465–71.
Neckar J, Szarszoi O, Koten L, et al. Effects of mitochondrial KATP modulators on cardioprotection induced by chronic high altitude hypoxia in rats. Cardiovas Res 2002; 55(3):567–75.
Gottlieb RA, Burleson KO, Kloner RA, Babior BM, Engler RL . Reperfusion injury induces apoptosis in rabbit cardiomyocytes. J Clin Invest 1994; 94(4):1621–8.
Fliss H and Grattinger D . Apoptosis in ischemic and reperfused rat myocardium. Circ Res 1996; 79:949–56.
Kajstura J, Cheng W, Reiss K, et al. Apoptotic and necrotic myocyte cell deaths are independent contributing variables of infarct size in rats. Lab Invest 1996; 74:86–107.
Zhao ZQ, Nakamura M, Wang NP, et al. Reperfusion induces myocardial apoptotic cell death. Cardiovasc Res 2000; 45:651–60.
Olivetti G, Quaini F, Sala R, et al. Acute myocardial infarction in human is associated with activation of programmed myocyte cell death in the surviving portion of the heart. J Mol Cell Cardiol 1996; 28:2005–16.
Gottlieb RA, Gruol DL, Zhu JY, Engler RL . Preconditioning in rabbit cardiomyicytes. J Clin Invest 1996; 97:2391–8.
Maulik N, Yoshida T, Engelman RM, et al. Ischemic preconditioning attenuates apoptotic cell death associated with ischemia/reperfusion. Mol Cell Biochem 1998; 186:139–45.
Piot CA, Martini JF, Bui SK et al. Ischemic preconditioning attenuates ischemia/reperfusion-induced activation of caspases and subsequent cleavage of poly(ADP-ribose) polymerase in rat heart in vivo. Cardiovasc Res 1999; 44:536–42.
Maulik N, Engelman RM, Rousou JA, et al. Ischemic preconditioning reduces apoptosis by upregulating anti-dearth gene Bcl-2. Circulation 1999; 100(19 Suppl):II369–75.
Nakamura M, Wang NP, Zhao ZQ, et al. Preconditioning decreases Bax expression, PMN accumulation and apoptosis in reperfused rat heart. Cardiovasc Res 2000; 45:661–70.
Oltvai ZN, Milliman CL and Korsmeyer SJ . Bcl-2 heterodimerizes in vivo with a consered homolog, Bax, that accelerates programmed cell death. Cell 1993; 74:609–19.
Chao DT, Korsmeyer SJ . Bcl-2 family: regulators of cell death. Annu Rev Immunol 1998; 16:395–419.
Adams JM, Cory S . The Bcl-2 protein family: arbiters of cell survival. Science 1998; 281:1322–6.
Wijsman JH, Jonker RR, Keijzer R, et al. A new method to detect apoptosis in paraffin sections: in situ end-labeling of fragmented DNA. J Histochem Cytochem 1993; 41(1):7–12.
Chang YC, and Xu YH . Expression of Bcl-2 inhibited Fas-mediated apoptosis in human hepatocellular carcinoma BEL- 7404 cells. Cell Res 2000; 10:233–42.
Guo BC and Xu YH . Bcl-2 over-expression and activation of protein kinase C suppress the trail-induced apoptosis in Jurkat T cells. Cell Res 2001; 11:101–6.
Foyouzi-Youssefi R, Arnaudeau S, Borner C, et al. Bcl-2 decreases the free Ca2+ concentration within the endoplasmic reticulum. Proc Natl Acad Sci USA 2000; 97:5723–8.
Zhang M, Zhang HQ, Xue SB . Effect of Bcl-2 and caspase-3 on calcium distribution in apoptosis of HL-60 cell. Cell Res 2000; 10:213–20.
Bogdanov MB, Ferrante RJ, Mueller G, Ramos LE, Martinou JC, Beal MF . Oxidative stress is attenuated in mice overexpressing BCL-2. Neurosci Lett 1999; 262:33–6.
Hockenbery DM, Oltvai ZN, Yin XM, Milliman CL, Korsmeyer SJ . Bcl-2 functions in an antioxidant pathway to prevent apoptosis. Cell 1993; 75:241–51.
Saikumar P, Dong Z, Patel Y, et al. Role of hypoxia-induced Bax translocation and cytochrome c release in reoxygenation injury. Oncogene 1998; 17:3401–15.
Gross A, Jockel J, Wei MC and Korsmeyer S . Enforced dimerization of Bax results in its translocation, mitochondrial dysfunction and apoptosis. EMBO J 1998; 17:3878–85.
Brocheriou V, Hagege AA, Oubenaissa A, et al. Cardiac functional improvement by a human Bcl-2 transgene in a mouse model of ischemia/reperfusion injury. J Gene Med 2000; 2:326–33.
Chen ZY, Chua CC, Ho YS, Hamdy RC, Chua BHL . Overexpression of Bcl-2 attenuates apoptosis and protects against myocardial I/R injury in transgenic mice. Am J Physiol 2001; 280:H2313–20.
Riva C, Chevrier C, Pasqual N, Saks V and Rossi A . Bcl-2/Bax protein expression in heart, slow-twitch and fast-twitch muscles in young rats growing under chronic hypoxia conditions. Mol and Cell Biochem 2001; 226:9–16.
Murry CE, Jennings RB, Reimer KA . Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium. Circulation 1986; 74:1124–36.
Acknowledgements
The study was supported by grants from National Natural Science Foundation of China, and the Science and Technology committee of Shanghai Municipality (02JC14038).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
DONG, J., ZHU, H., ZHU, W. et al. Intermittent hypoxia attenuates ischemia/reperfusion induced apoptosis in cardiac myocytes via regulating Bcl-2/Bax expression. Cell Res 13, 385–391 (2003). https://doi.org/10.1038/sj.cr.7290184
Received:
Revised:
Accepted:
Issue date:
DOI: https://doi.org/10.1038/sj.cr.7290184
Keywords
This article is cited by
-
Effects of sleep apnea hypopnea syndromes on cardiovascular events: a systematic review and meta-analysis
Sleep and Breathing (2022)
-
Chronic Intermittent Hypobaric Hypoxia Improves Cardiac Function through Inhibition of Endoplasmic Reticulum Stress
Scientific Reports (2017)
-
In Vivo Cardioprotective Effects and Pharmacokinetic Profile of N-Propyl Caffeamide Against Ischemia Reperfusion Injury
Archivum Immunologiae et Therapiae Experimentalis (2017)
-
Erythropoietin levels in patients with sleep apnea: a meta-analysis
European Archives of Oto-Rhino-Laryngology (2017)
-
Triptolide Attenuates Myocardial Ischemia/Reperfusion Injuries in Rats by Inducing the Activation of Nrf2/HO-1 Defense Pathway
Cardiovascular Toxicology (2016)
