Calcium preconditioning inhibits mitochondrial permeability transition and apoptosis.
We tested the hypothesis whether calcium preconditioning (CPC) reduces reoxygenation injury by inhibiting mitochondrial permeability transition (MPT). Cultured myocytes were preconditioned by a brief exposure to 1.5 mM calcium (CPC) and subjected to 3 h of anoxia followed by 2 h of reoxygenation (A-R). Myocytes were also treated with 0.2 microM/l cyclosporin A (CsA), an inhibitor of MPT, before A-R. A significant increase of viable cells and reduced lactate dehydrogenase release was observed both in CPC- and CsA-treated myocytes compared with the A-R group. Cytochrome c release was predominantly observed in the cytoplasm of myocytes in the A-R group in contrast with CPC- or CsA-treated groups, where it was restricted only to mitochondria. Similarly, the cell death by apoptosis was also markedly attenuated in these groups. Electron-dense Ca(2+) deposits in mitochondria were also less frequent. Atractyloside (20 microM/l), an adenine nucleotide translocase inhibitor, caused changes similar to those in the A-R group, suggesting a role of MPT in A-R injury. Protection by inhibition of MPT by CsA and CPC suggests that MPT plays an important role in reoxygenation/reperfusion injury. The data further suggest that preconditioning inhibits MPT by inhibiting Ca(2+) accumulation by mitochondria.
Xu
M
M
Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45267-0529, USA.
Wang
Y
Y
Hirai
K
K
Ayub
A
A
Ashraf
M
M
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001278:Atractyloside / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000032:analysis / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D020287:In Situ Nick-End Labeling; D019157:Ischemic Preconditioning, Myocardial; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000648:ultrastructure; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D051381:Rats
D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D001278:Atractyloside; D016572:Cyclosporine; D002118:Calcium