2Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-3181
3Research Institute of Mitoengineering, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-5945
* To whom correspondence should be addressed.
Received June 4, 2012; Revision received September 10, 2012
The mechanism of the effect of tert-butyl hydroperoxide (tBHP) on the kinetics of decrease in liver mitochondrial ΔΨ (transmembrane electric potential) in response to successive additions of tBHP in low concentrations has been studied. FeSO4 was found to increase significantly the damaging effect of tBHP; this effect was shown to increase in the presence of low concentrations of Ca2+ starting from 2 µM CaCl2. Cyclosporin A prevents these effects. The data show that the damaging effect of low concentrations of tBHP in the course of pyruvate oxidation in isolated liver mitochondria is caused by the opening of the nonspecific Ca2+-dependent cyclosporin A-sensitive pore in the inner mitochondrial membrane. Application of a method of studying oxidative stress regulators, developed in this work, is illustrated by an example of the prooxidant action of ascorbate. This method is proposed for studying mitochondria in hemochromatosis, a pathology caused by excessive accumulation of iron.
KEY WORDS: oxidative stress, liver mitochondria, tert-butyl hydroperoxide, pyruvate, cyclosporin A-sensitive pore, hemochromatosis