Author(s)

Takuya Ichimura, Mika Ito, Kiyoshi Takahashi, Kyohei Oyama, Koichi Sakurai

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An early event in the induction of apoptosis is cytochrome c (Cyt c) release from mitochondria. We investigated the involvement of mitochonrial permeability transition (MPT) and mitochondrial swelling in Cyt c release from mitochondria treated with alloxan and/or calcium (Ca²⁺). When mitochondria were treated with a high concentration of Ca²⁺. alone or Ca²⁺. with alloxan (alloxan-Ca²⁺), the MPT was accompanied by mitochondrial swelling and the release of Cyt c. Cyclosporin A prevented the induction of MPT but only slightly decreased the release of Cyt c. High molecular weight polyethylene glycol almost completely inhibited MPT-dependent osmotic mitochondrial swelling and Cyt c release. However, MPT-independent mitochondrial swelling and Cyt c release induced by exogenous K⁺. were inhibited by the high molecular weight polyethylene glycol. Ruthenium red strongly decreased the amount of Cyt c released. These results suggest that mitochondrial swelling but not MPT is necessary for Cyt c release induced by Ca²⁺ alone or alloxan and Ca²⁺.

Mitochondrial Swelling; Cytochrome C Release; Calcium; Alloxan; Mitochondrial Permeability Transition

Ichimura, T. , Ito, M. , Takahashi, K. , Oyama, K. and Sakurai, K. (2011) Involvement of mitochondrial swelling in cytochrome c release from mitochondria treated with calcium and Alloxan. Journal of Biophysical Chemistry, 2, 10-18. doi: 10.4236/jbpc.2011.21002.