Role of sarcolemmal ATP-sensitive potassium channel in oxidative stress-induced apoptosis: mitochondrial connection.
From time of their discovery, sarcolemmal ATP-sensitive K+ (sarcK ATP) channels were thought to have an important protective role in the heart during stress whereby channel opening protects the heart from stress-induced Ca2+ overload and resulting damage. In contrast, some recent studies indicate that sarcK ATP channel closing can lead to cardiac protection. Also, the role of the sarcK ATP channel in apoptotic cell death is unclear. In the present study, the effects of channel inhibition on apoptosis and the specific interaction between the sarcK ATP channel and mitochondria were investigated. Apoptotic cell death of cultured HL-1 and neonatal cardiomyocytes following exposure to oxidative stress was significantly increased in the presence of sarcK ATP channel inhibitor HMR-1098 as evidenced by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling and caspase-3,7 assays. This was paralleled by an increased release of cytochrome c from mitochondria to cytosol, suggesting activation of the mitochondrial death pathway. sarcK ATP channel inhibition during stress had no effect on Bcl-2, Bad, and phospho-Bad, indicating that the increase in apoptosis cannot be attributed to these modulators of the apoptotic pathway. However, monitoring of mitochondrial Ca2+ with rhod-2 fluorescent indicator revealed that mitochondrial Ca2+ accumulation during stress is potentiated in the presence of HMR-1098. In conclusion, this study provides novel evidence that opening of sarcK ATP channels, through a specific Ca2+-related interaction with mitochondria, plays an important role in preventing cardiomyocyte apoptosis and mitochondrial damage during stress.
Marinovic
Jasna
J
Department of Anesthesiology, Medical College of Wisconsin, Miwaukee, WI 53226, USA.
Ljubkovic
Marko
M
Stadnicka
Anna
A
Bosnjak
Zeljko J
ZJ
Bienengraeber
Martin
M
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001549:Benzamides / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D004594:Electrophysiology; D054086:KATP Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012508:Sarcolemma / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051025:bcl-Associated Death Protein / Q000378:metabolism
D001549:Benzamides; D054086:KATP Channels; D026902:Potassium Channel Blockers; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D045304:Cytochromes c; C410297:HMR 1098; D002118:Calcium