Transgenic Expression of Bcl-2 Modulates Energy Metabolism, Prevents Cytosolic Acidification During Ischemia, and Reduces Ischemia/Reperfusion Injury

• Published in: Circulation Research Vol. 95; no. 7; pp. 734 - 741
• Main Authors: Imahashi, Kenichi, Schneider, Michael D, Steenbergen, Charles, Murphy, Elizabeth
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.10.2004; Lippincott
• Subjects: Adenosine Triphosphate - metabolism; Anaerobiosis; Animals; Apoptosis; Biological and medical sciences; Blotting, Western; Cytosol - chemistry; Energy Metabolism - drug effects; Female; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genes, bcl-2; Glycolysis; Humans; Hydrogen-Ion Concentration; Male; Mice; Mice, Transgenic; Mitochondria, Heart - drug effects; Mitochondria, Heart - physiology; Myocardial Contraction; Myocardial Infarction - pathology; Myocardial Ischemia - metabolism; Myocardial Reperfusion Injury - metabolism; Nuclear Magnetic Resonance, Biomolecular; Oligomycins - pharmacology; Phosphocreatine - metabolism; Porins - metabolism; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; Proto-Oncogene Proteins c-bcl-2 - physiology; Proton-Translocating ATPases - physiology; Recombinant Fusion Proteins - physiology; Vertebrates: cardiovascular system; Voltage-Dependent Anion Channels; Energy metabolism; Magnetic resonance; Acidification; Transgenic animal; Cardiovascular disease; magnetic resonance spectroscopy; reperfusion injury; Vertebrata; Mitochondria; Mammalia; Reperfusion; Ischemia; Models; Circulatory system; Lesion; transgenic models
• ISSN: 0009-7330; 1524-4571; 1524-4539
• DOI: 10.1161/01.RES.0000143898.67182.4c

The antiapoptotic protein Bcl-2 is targeted to the mitochondria, but it is uncertain whether Bcl-2 affects only myocyte survival after ischemia, or whether it also affects metabolic functions of mitochondria during ischemia. Hearts from mice overexpressing human Bcl-2 and from their wild-type littermates (WT) were subjected to 24 minutes of global ischemia followed by reperfusion. During ischemia, the decrease in pHi and the initial rate of decline in ATP were significantly reduced in Bcl-2 hearts compared with WT hearts (P <0.05). The reduced acidification during ischemia was dependent on the activity of mitochondrial F1F0-ATPase. In the presence of oligomycin (Oligo), an F1F0-ATPase inhibitor, the decrease in pHi was attenuated in WT hearts, but in Bcl-2 hearts, Oligo had no additional effect on pHi during ischemia. Likewise, addition of Oligo to WT hearts slowed the rate of decline in ATP during ischemia to a level similar to that observed in Bcl-2 hearts, but addition of Oligo had no significant effect on the rate of decline in ATP in Bcl-2 hearts during ischemia. These data are consistent with Bcl-2–mediated inhibition of consumption of glycolytic ATP. Furthermore, mitochondria from Bcl-2 hearts have a reduced rate of consumption of ATP on uncoupler addition. This could be accomplished by limiting ATP entry into the mitochondria through the voltage-dependent anion channel, and/or the adenine nucleotide transporter, or by direct inhibition of the F1F0-ATPase. Immunoprecipitation showed greater interaction between Bcl-2 and voltage-dependent anion channel during ischemia. These data indicate that Bcl-2 modulation of metabolism contributes to cardioprotection.