[Isolation and purification of human blood plasma proteins able to form potassium channels in artificial bilayer lipid membrane].

Protein fraction able to induce K(+)-selective transport across bilayer lipid membrane was isolated from human blood plasma with the use of the detergent and proteolytic enzyme-free method developed at our laboratory. After addition of the studied sample to the artificial membrane in the presence of 100 mM KCl, a discrete current change was observed. No channel activity was recorded in the presence of calcium and sodium ions. Channel forming activity of fraction was observed only in the presence of K+. Using a threefold gradient of KCl in the presence of studied proteins the potassium-selective potential balanced by voltage of -29 mV was registered. This value is very close to the theoretical Nernst potential in this case. This means that the examined ion channel is cation-selective. According to data obtained with MS-MALDI-TOF/TOF and database NCBI three protein components were identified in isolated researched sample.

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.

[Localization in a cell of a protein forming the ATP-dependent potassium-selective channels in the bilayer lipid membrane. An ultrastructural study].

The localization in the cell of the protein forming the ATP-dependent potassium-selective channels in the bilayer lipid membrane has been studied. The electron microscope investigation of rat liver and heart tissue sections after their incubation with Abs against this protein and the visualization of the protein with secondary Abs conjugated with colloid gold were carried out. Colloid gold particles were observed both in mitochondrial membranes and in membranes of endoplasmic and sarcoplasmic reticulum. In heart mitochondria, these particles were significantly greater than in liver mitochondria. The localization of the channel protein both in mitochondria and reticulum, as well as the structural similarity between the mitochondrial channel and the precursor of calreticulin suggest that the channel protein belongs to the family of calreticulins. The possible function of the protein as a channel subunit of the mitochondrial ATP-dependent potassium channel is discussed.

[Purification of the mitochondrial calcium uniporter from the beef heart and characterization of its properties].

A low-molecular-weight component (LMC) inducing selective transport of calcium across the bilayer lipid membrane has been isolated from mitochondria of the bovine heart by the method developed in our laboratory, which excludes the use of detergents and proteolytic enzymes. It was shown that, in the presence of 10 mM CaCl2, LMC forms conduction channels in the membrane multiples of 5 pS. The specific inhibitor of mitochondrial calcium uniporter, ruthenium red, closes Ca2(+)-induced channels formed in the membrane by LMC. In the absence of calcium or in the presence of potassium ions only, the component is incapable of forming channels of conduction. It was shown using nuclear magnetic resonance that LMC is a complex consisting of lipids, amino acids, and sugars with a molecular weight of 1-2 kDa.

[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 several flavonoid-containing plant preparations on activity of mitochondrial ATP-dependent potassium channel.

Flavonoid-containing plant preparations (water soluble extracts of Pentaphylloides fruticosa [Extralife], Emblica officinalis Gaerth [Amla], and Bergenia crassifolia [Bergenia]) produced a dose-dependent and tissue-specific effect on activity of mitochondrial ATP-dependent potassium channel. The effect of these preparations was biphasic (activation and inhibition). The activating effect of Extralife was one order of magnitude higher than that of Amla and Bergenia and was observed in a wider concentration range. The activating effect of preparations was abolished by inhibitors of the mitochondrial ATP-dependent potassium channel, which attested to specificity of their influence on mitochondrial channel. Under in vivo conditions, the antihypoxic effect of Extralife was partially abolished by mitochondrial ATP-dependent potassium channel inhibitor 5-hydroxydecanoate.