O. B. Vadzyuk

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

We demonstrated using PBFI K⁺-sensitive fluorescent probe an enhancement of both components of K⁺-cycle – the ATP-sensitive K⁺-uptake and quinine-sensitive K⁺/H⁺-exchange – under the Ca²⁺ induced opening­ of mitochondrial permeability transition pore (MPTP) in rat myometrium mitochondria. Addition of CaCl₂ (100 μM) to K⁺-free medium results in the enhancement of reactive oxygen species (ROS) production, which was eliminated by cyclosporine A. Addition of CaCl₂ to K⁺-rich medium did not increase the rate of ROS production, but blocking of mitoK⁺_ATP-channels with glybenclamide (10 μM) increased production of ROS. We conclude that K⁺-cycle exerts a protective influence in mitochondria from rat myometrium by regulation of matrix volume and rate of ROS production under the condition of Ca²⁺-induced MPTP.