1995 Fiscal Year Final Research Report Summary
Oxidative damage to mitochondria is mediated by the Ca2+-dependent inner membrane permeability transition
| Project/Area Number |
06454376
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General surgery
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| Research Institution | Kansai Medical University |
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Principal Investigator |
TANAKA Takaya Kansai Medical University, 医学部, 助教授 (70121952)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Anoxia / recoxygenation / cyclosporin A / DiOC6 / JC-1 / thapsigargin / mitochondrial membrane potential / permeability transition |
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| Research Abstract |
The aim of this study is to evaluate changes in mitochondrial function of cultured MDCK cell by laser scanning confocal microscopy and a digitized-fluorescence-imaging during chemical anoxia/reoxygenation (A/R). Chemical anoxia was induced with rotenone and 2-deoxyglucose, inhibitor of a site I of the electron transport chain and glycolysis, respectively. Oxidative metabolism was restored by the addition of a short odd-chain fatty acid (heptanoate). Cytosolic free Ca^<2+> measured by Futa-2 increased gradually about 50% after 30 min of anoxia and returned to initial value immediately after reoxygenation. Anoxia up to 60 min or 30 min of anoxia followed by 30 min of reoxygenation had no effect on cell viability and mitochondrial membrane potential (DELTAPSI_m) assessed by DiOC6 and JC-1. In the presence of thapsigargin, a specific inhibitor of the Ca-ATPase of the endoplasmic reticulum, DELTAPSI_m was stable during 60 min of anoxia. However, DELTAPSI_m decreased with reoxygenation after 30 min of anoxia. The sensitization of A/R by thapsigargin disappeared in the presence of cyclosporin A,a specific inhibitor of mitochondrial inner membrane pore opening. We conclude that reoxygenation-induced Ca^<2+> redistribution and the mitochondrial membrane permeability transtion are involved in A/R injury of MDCK cell.
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