O. B. Vadzyuk, S. A. Kosterin

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: olga_vadzyuk@hotmail.com

Induction of mitochondrial swelling and increased generation of reactive oxygen forms by Ca ions have been shown in suspension of mitochondria from rat uterus. These effects were suppressed by the blocker of mitochondrial Ca²⁺-uniporter ruthenium red and MPTP inhibitor сyclosporin A, that evidences that the induction of mitochondrial permeability transition pore by Ca ions takes place. Ca²⁺-induced mitochondrial swelling was blocked by ATP-sensitive channel blocker glybenclamide but only if K⁺ was present in the incubation medium. We also demonstrated that Ca²⁺-induced mitochondrial swelling can be eliminated in the presence of ROS scavengers N-acetyl cysteine and ascorbate. This effect of scavengers was also sensitive to K⁺ and was not revealed in the medium that contained equimolar NaCl instead of KCl. Thus, our data gave us grounds to assume that the induction of MPTP by Ca ions evokes the activation of mitochondrial ATP-sensitive K⁺-channels, which are mediated by ROS.