Glucose Uptake and Glycolysis Reduce Hypoxia-induced Apoptosis in Cultured Neonatal Rat Cardiac Myocytes
Myocardial ischemia/reperfusion is well recognized as a major cause of apoptotic or necrotic cell death. Neonatal rat cardiac myocytes are intrinsically resistant to hypoxia-induced apoptosis, suggesting a protective role of energy-generating substrates. In the present report, a model of sustained h...
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Published in | The Journal of biological chemistry Vol. 274; no. 18; pp. 12567 - 12575 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
30.04.1999
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Subjects | |
Online Access | Get full text |
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Summary: | Myocardial ischemia/reperfusion is well recognized as a major cause of apoptotic or necrotic cell death. Neonatal rat cardiac
myocytes are intrinsically resistant to hypoxia-induced apoptosis, suggesting a protective role of energy-generating substrates.
In the present report, a model of sustained hypoxia of primary cultures of Percoll-enriched neonatal rat cardiac myocytes
was used to study specifically the modulatory role of extracellular glucose and other intermediary substrates of energy metabolism
(pyruvate, lactate, propionate) as well as glycolytic inhibitors (2-deoxyglucose and iodoacetate) on the induction and maintenance
of apoptosis. In the absence of glucose and other substrates, hypoxia (5% CO 2 and 95% N 2 ) caused apoptosis in 14% of cardiac myocytes at 3 h and in 22% of cells at 6â8 h of hypoxia, as revealed by sarcolemmal membrane
blebbing, nuclear fragmentation, and chromatin condensation (Hoechst staining), terminal deoxynucleotidyl transferase-mediated
dUTP nick end labeling (TUNEL) staining, and DNA laddering. This was accompanied by translocation of cytochrome c from the mitochondria to the cytosol and cleavage of the death substrate poly(ADP-ribose) polymerase. Cleavage of poly(ADP-ribose)
polymerase and DNA laddering were prevented by preincubation with the caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl
ketone (zVAD-fmk) and benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethyl ketone (zDEVD-fmk), indicating activation of caspases
in the apoptotic process. The caspase inhibitor zDEVD-fmk also partially inhibited cytochrome c translocation. The presence of as little as 1 m m glucose, but not pyruvate, lactate, or propionate, before hypoxia prevented apoptosis. Inhibiting glycolysis by 2-deoxyglucose
or iodoacetate, in the presence of glucose, reversed the protective effect of glucose. This study demonstrates that glycolysis
of extracellular glucose, and not other metabolic pathways, protects cardiac myocytes from hypoxic injury and subsequent apoptosis. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.274.18.12567 |