Hypoxia-Reoxygenation Induced Cardiac Mitochondrial Dysfunction
Abstract
Objectives: Cellular response to low oxygen tension is altered by severity and duration of hypoxia. Although the subject has been studied extensively,
mechanisms leading to hypoxia-reoxygenation damage remain undefined. Here, we investigated the effect of long term continuous hypoxia (48
hours) on cardiac derived HL-1 cells, mainly the role of mitochondria in cellular energy and reactive oxygen species homeostasis.
Materials and Methods: In this study, mammalian atrium derived HL-1 cells were cultured either in long term hypoxia (48 hours, 1% O2) or in
normoxia (48 hours, 21% O2) conditions. Mitochondrial membrane potential and reactive oxygen species (ROS) level was measured using florescent
dyes in a confocal microscope. GAPDH protein levels were detected by western blotting in normoxic control and hypoxic cells.
Results: Present results demonstrate that, 48 hours of hypoxia did not alter baseline mitochondrial membrane potential and its oxidative respiration
capacity in cardiac HL-1 cells. The mitochondrial depolarization response to in reoxygenation period of oxygen deprived cells was slower in hypoxic
cells. In hypoxic cells, basal ROS levels were higher whereas hydrogen peroxide response was smaller when compared with the normoxic control
group. GAPDH protein levels were unaltered between groups.
Conclusion: Present results indicate that, persistent mitochondrial oxidation phosphorylation uncoupling may lead to an over production of ROS.
Keywords
HL-1 Cells, Hypoxia, Mitochondrial Membrane Potential, Reactive Oxygen Species
References
- 1. Liu B, Tewari AK, Zhang L, et al. Proteomicanalysis of protein tyrosine nitration afteri schemiareperfusio ninjury:mitochondria as themajortarget. Biochim Biophys Acta 2009;1794:476-485.
- 2. Solaini G, Harris DA. Biochemicaldysfunction in heart mitochondria exposed to ischaemia and reperfusion. Biochem J. 2005;390:377-394.
- 3. Semenza GL.Hypoxia-induciblefactor 1: masterregulator of O2 homeostasis. CurrOpinGenet Dev. 1998;8:588-594.
- 4. Semenza GL, Roth PH, Fang HM, et al. Transcriptional regulation of genesencoding glycolytic enzymes by hypoxia-induciblefactor 1. J BiolChem 1994;269:23757-23763.
- 5. Semenza GL, Jiang BH, Leung SW, et al. Hypoxia response elements in thealdolase A, enolase 1, andlactatedehydrogenase A gene promoterscontain essential binding sitesfor hypoxia-inducible factor 1.J BiolChem 1996;271:32529-32537.
- 6. Ebert BL, Firth JD, Ratcliffe PJ. Hypoxia and mitochondrial inhibitorsregulate expression of glucose transporter-1 viadistinctCis-actingsequences. J Biol Chem 1995;270:29083-29089.
- 7. Turrens JF. Mitochondrial formation of reactive oxygen species. J Physiol 2003;552:335-344.
- 8. Papandreou I, Cairns RA, Fontana L, et al. HIF-1 mediates adaptation to hypoxia by actively downregulating mitochondrial oxygen consumption. Cell Metab. 2006;3:187-197.
- 9. Chandel NS, McClintock DS, Feliciano CE, et al. Reactive oxygen species generated at mitochondrial Complex III stabilize hypoxia-inducible factor-1alpha during hypoxia: a mechanism of O2 sensing. J Biol Chem. 2000;275:25130-25138.
- 10. Chandel NS, Maltepe E, Goldwasser E, et al. Mitochondrial reactive oxygen species trigger hypoxia-induced transcription. Proc Natl Acad Sci. 1998;95:11715-11720.