[A role for calreticulin in functioning of mitochondrial ATP-dependent potassium channel].

Homology of the amino acid sequence of the mitochondrial potassium-transporting protein (MW 57kDa), having the properties of a channel subunit of the mitochondrial ATP-dependent potassium channel, and calreticulin (MW 55kDa) was detected by MALDI-TOF-TOF analysis method. Inhibitory analysis of ATP-dependent potassium transport in mitochondria with polyclonal antibodies to calreticulin was carried out. A dose-dependent inhibition of potassium transport in mitochondria by these antibodies was shown. The maximum value of inhibition was 55-60%. Based on these data it is hypothesized that at least two types of ATP-sensitive potassium channels are localized in mitochdndrial membrane. It is expected that the type of mitochondrial ATP-dependent potassium channel, which includes homologous calreticulin protein is localized mainly at mitochondrial and reticulum membrane contact sites.

Effects of flavonoid-containing preparation Extralife on hydrogen peroxide production and functioning of mitochondrial ATP-dependent potassium channel.

Extralife, a Pentaphylloides fruticos extract, in concentrations of 0.005-10 µg/ml dose-dependently increased H2O2 production in rat heart mitochondria in the presence of respiration substrates. Extralife decreased ATP-induced accumulation of H2O2 related to inhibition of mitochondrial ATP-dependent potassium channel. This effect was observed only at low doses of the adaptogen (0.05-3 µg/ml). High doses of the substance (5-10 µg/ml) did not abolish ATP-dependent production of H2O2 and increased the rate of H2O2 generation by the mitochondria. We concluded that Extralife in trace concentrations could activate mitochondrial ATP-dependent potassium channel and decrease H2O2 accumulation in the mitochondria.

[Determination of the antioxidant properties of activators of mitochondrial ATP-dependent potassium channels with the Amplex Red fluorescent indicator].

The effect of adaptogens-antihypoxants that participate in the activation of mitochondrial ATP-dependent potassium channels (mitoK(ATP)) at the oxidation of the Amplex Red (AR) fluorescent indicator in a peroxidase system was tested. It was shown that Extralife, Hypoxen, taurine, and synthetic antioxidant ionol can be arranged in the following row, according to the fluorescence inhibition activity: Extralife > Hypoxen > > ionol > taurine; their effect was shown to be concentration-dependent. The calculated K(i) value of fluorescence indicators demonstrate fast and slow phases of inhibition of the AR oxidation by Extralife and Hypoxen. The fast phase occurs in the presence of microdoses (0.05-3 microg/mL) of adaptogens and is related to the competition for H2O2, which is in agreement with our previous data on the mitoK(ATP) activation by doses of adaptogens related to the H2O2 consumption. The slow phase is characteristic of high adaptogen and ionol concentrations and is related to the competition for phenoxyl radicals of resorufin formed during AR oxidation. The obtained results allow one to suggest the application of a highly sensitive model peroxidase system with AR for the preliminary testing of compounds activating mitoK(ATP) channels.

Activity of mitochondrial ATP-dependent potassium channel in animals with different resistance to hypoxia before and after the course of hypoxic training.

Activity of mitochondrial ATP-dependent potassium channel in rats with high genetically determined resistance to hypoxia was higher than in sensitive animals. Adaptation of low resistant rats to hypoxia was accompanied by activation of the channel, facilitation of potassium recycling in mitochondria, and a decrease in the rate of H2O2 formation. Our results indicate that mitochondrial ATP-dependent potassium channel plays an important role in the delayed mechanisms of animal's adaptation to hypoxia.

[Effect of hypoxenum on bioenergetic processes in mitochondria and the activity of ATP-sensitive potassium channel].

The effect of hypoxenum on bioenergetic processes in heart and liver mitochondria of rats, connected with respiration, the generation of hydrogen peroxide, and the activity of ATP-sensitive K-channel ((mitoK)ATP) has been studied. It was shown that hypoxenum in the concentration range of 0.05-10 microg/ml stimulates respiration, increases the coupling in the respiratory chain, and enhances the formation of H2O2 and energy-dependent swelling associated with potassium transport in mitochondria. Hypoxenum removes the inhibitory effect of ATP on the energy-dependent swelling of mitochondria and partially reduces the accumulation of H2O2 in the presence of ATP. The role of antihypoxic and antioxidant action of hypoxenum associated with the activation of (mitoK)ATP is discussed.

[Age-related changes in the functioning of the mitochondrial potassium-transporting system].

Changes in the rate of respiration and functioning of the ATP-dependent potassium channel the liver and heart mitochondria of one-, three-, eight-, and twenty four-month-old Wistar male rats have been investigated. It was shown that the activity of the channel in the mitochondria of both tissues in 24-months-old animals decreases more than three times, and the content of potassium, 1.5-2 times compared with young one-month-old rats. The changes occur against the background of age-related decrease of energy supply in mitochondria, the respiratory complex-I underganig the greatest changes upon aging. The decrease of channel activity may be the result of changes in channel sensitivity to modulators and a decrease in the expression of mitochondrial K(+)-transporting channel-protein with a molecular mass of 5.5 kDa upon aging found in this work. As a result, the functioning of not only the mitoK(ATP) but also the whole mitochondrial potassium cycle is impaired.

[Effect of taurine on the ion transport system in mitochondria].

The influence of taurine on the ATP-dependent mitochondrial swelling, which characterizes the activity of the ATP-dependent K+ channel and the opening of Ca(2+)-dependent pores differing in the sensitivity to cyclosporin A in rat liver mitochondria has been studied. It was shown that taurine at small (0.5-125 microM) concentrations produces a stimulating effect on the ATP-dependent mitochondrial swelling. Taurine in physiological concentrations (0.5-20 mM) di not affect the ATP-dependent mitochondrial swelling and cyclosporin A-insensitive palmitate/Ca(2+)-activated pore formation in mitochondria. Taurine in these concentrations increased the rate of cyclosporin A-sensitive swelling induced by Ca2+ and P(i) and decreased the Ca2+ capacity of mitochondria.

[Effect of heavy metals on wheat seedlings; activation of antioxidant enzymes]. / Deistvie tiazhelykh metallov na prorostki pshenitsy; aktivirovanie antioksidantnykh fermentov.

Accumulation of heavy metals in wheat grain exposed to multicomponent pollutants (industrial waste-water) was studied. The absolute content of metals (Zn, Cd, Cu, Cr, Ni, Pb, and Mn) was found to be determined by the extent of purification of wastewater. An increase in the degree of grain contamination with heavy metals was accompanied by activation of antioxidant enzymes (superoxide dismutase, EC 1.15.1; catalase, EC 1.11.1.6; and peroxidase, EC 1.11.1.7) in leaves and activation of superoxide dismutase and peroxidase in roots. The ratio of activity of membrane enzymes to activity of cytosol enzymes was demonstrated to be high. It was concluded that the membrane-tropic effect of multicomponent contaminants was due to accumulation of heavy metals capable of inducing the antioxidant protection in the next generation of wheat seedlings.

[Proteolytic activity of viper venoms]. / Proteoliticheskaia aktivnost' iada gadiukovykh zmei.

Proteolytic activities of venoms of vipers kept in a serpentarium for three years or captured in various environmental regions were estimated. Gurza venom contained considerable amounts of protein (830-930 micrograms/mg venom) and displayed a high proteolytic activity by tyrosine (80-140 micrograms/min mg protein). The proteolytic activity did not depend on season, as well as age or physiological state of snakes in the reproductive period. The proteolytic activity of venom in gurza offspring was similar to that in parent specimens. Proteolytic activities (by tyrosine) of venoms produced by Radde's vipers and common vipers were 77-90 and 18-36 micrograms/min mg protein, respectively. The proteolytic activity of venom in common vipers native to the north European part of Russia was 20-30% higher than that in common vipers inhabiting southern European Russia. An inhibition assay found various ratios of metalloendopeptidase and serine endopeptidase activities in venoms of gurza, Radde's viper, and common viper.

[Effect of IAA on the photophosphorylation of pea isolated chloroplasts]. / Viiianie iuk na fotofosforilirovanie izolirovannykh Khloroplastov gorokha

Effect of IAA (10(-10)-10(-3) M) on photophosphorylation, NADP reduction and the oxygen exchange is investigated. It is shown that low concentrations of IAA (10(-10)-10(-7) M) increase the photophosphorylation reaction and the flow of electrones to NADP under the phosphorylation conditions in the chloroplasts, and their effect on the O2 exchange is not the same in different types of photophosphorylation. It is supposed that the effect of IAA on the photophosphorylation is connected with H292 metabolism in chloroplasts and with catalase and peroxidase functions.

[The fluorescence method of peroxide determination in isolated chloroplasts]. / Fluorestsentnyi metod opredeleniia perekisi vodoroda v izolirovannykh khloroplastakh

High-sensitive method of peroxide estimation in suspension of pea chloroplasts is worked out. It is based on a decrease of esculatin fluorescence due to its oxidation by peroxide with peroxidase.