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The effects of a single injection of the reduced form of glutathione on the expression of the KCNJ8 and KCNJ11 genes encoding Kir6.1 and Kir6.2 subunits of ATP-sensitive potassium (KATP) channels and on Ca2+-induced nonspecific mitochondrial permeability transition pores (mPTP) opening in the heart of old rats were studied. Changes in biochemical parameters characterizing the intensity of oxidative processes in organelles at the action of glutathione were also studied. The expression levels of Kir6.1 і Kir6.2 subunits KATP channels were determined using reverse transcription and quantitative PCR. It was shown that after the administration of glutathione to old rats, the expression of KATP channel subunits significantly increased, namely for Kir6.1 9.3 times, for Kir6.2 2.6 times. The use of glutathione in older animals inhibited mPTP opening: reduced the amplitude of spontaneous and Ca2+-induced swelling of mitochondria. An important consequence of the action of glutathione during aging was a decrease in the rate of generation of superoxide (•О2 -) and hydroxyl (•ОН) radicals, as well as the content of hydrogen peroxide respectively in 1.8, 2.5 and 3.2 times compared with these figures in older animals without treatment. Glutathione also reduced lipid peroxidation, particularly pools of diene conjugates (2.5-fold) and malonic dialdehyde (1.8-fold). Thus, glutathione significantly increases the expression of KCNJ8 and KCNJ11 genes encoding Kir6.1 and Kir6.2 subunits of KATP channels in the heart of rats, regulates MP, preventing its opening, and reduces oxidative stress, indicating its important role in myocardial protection. [ABSTRACT FROM AUTHOR]

The objective of the present study was to investigate the effect of propargylglycine (PAG), an inhibitor of the CSE-dependent pathway of hydrogensulfide synthesis, on the endotheliumdependent relaxation of aortic smooth muscle (SM) in old rats. It was found a violation of SM relaxation in this group of animals. The average value of its amplitude was 7.5 ± 1.4% compared with 64.9 ± 3.5% in healthy adult rats. PAG significantly improved endothelium-dependent relaxation in old rats, the average value of its amplitude increased from 7.5 ± 1.4% to 44,5 ± 3,2%. This effect was due to suppression of superoxide anion generation by inhibition of xanthineoxidase activity. [ABSTRACT FROM AUTHOR]

The effect of the amino acid L-cysteine on the hydrogen sulfide content, oxidative stress indicators and kinetic characteristics of Ca2+-induced mitochondrial swelling in the heart of aged rats were investigated. Single administration to old rats of L-cysteine (121 mg/kg) was shown to suppress spontaneous and Ca2+-induced swelling of mitochondria, which manifested in a decrease in the amplitude of these processes and indicated prevention of mPTP formation in the heart. During aging, the mitochondrial pools of hydrogen sulfide decreased against the background of violation of constitutive NO synthesis, and also a significant increase of inducible and salvage NO synthesis. The use of L-cysteine resulted in an increase of 2.56-fold the content of hydrogen sulfide in the mitochondria of the heart of old rats (6.015 ± 0,74 nmol/mg protein) compared to animals without the introduction of the amino acid (2.35 ± 0,25 nmol/mg protein). Hence, under these conditions, the synthesis of hydrogen sulfide in the mitochondria was restored, probably due to the activation of H2S-synthesizing enzymes by their substrate, which contributed to significant inhibition of inducible NO synthesis by 1.73 times and a decrease by 2 times of nitrate reductase and arginase activity. The introduction of L-cysteine to old animals significantly (1.5 times) reduced uric acid pools, which may indicate suppression of superoxide radicals formation, and significantly decreased pools of diene conjugates (7 times), which indicates the suppression of oxidative stress in the early stages of lipid peroxidation. Thus, the results of studies indicate the participation of L-cysteine in the stimulation of endogenous hydrogen sulphide synthesis in mitochondria, which contributes to the reduction of oxidative stress in organelles and modulation of changes in the permeability of mitochondrial membranes. This fact speaks to the importance of such a gas transmitter as hydrogen sulphide, as a regulatory factor in the cardiovascular system, which modulates the functions of cells and their organelles. [ABSTRACT FROM AUTHOR]

We studied the parameters of mitochondrial respiration in the suspension of isolated heart mitochondria from old rats using glutamate and succinate - the substrates for the I and II respiratory chain complexes, as well as the dependence of this process on the action of calcium ions. It was shown that Ca2+ influx dynamics in old rat heart mitochondria is different from that in adult control organelles, and the maximum of fluorescence of the calcium-sensitive dye Fluo-4 AM at Ca2+ concentration 100 mol/l was observed at 3rd minute and was 27% higher than in the control. Consequently, in older rats, we observed a more sharp increase in intramitochondrial calcium. Despite the moderate increase (using succinate) or no different from that in adult animals (using glutamate) of the V2 indicator in the 24-month rats, ADP-stimulated respiration rate decreased, which led to a decrease in respiratory control ratio (RCR) by Chance and Lardy 1.18 and 1.6 times (with oxidation of succinate) and 1.18 and 1.4 times (in the presence of glutamate). However, the efficiency of phosphorylation of ATP, which is characterized by the ratio of ATP synthesis and oxygen absorption (ADP/O), did not change, nor did the velocity of phosphorylation of ATP (ADP/At). The effect of calcium ions on mitochondrial respiration in adult rats was dose dependent. At low concentrations of cation (10-7 mol/l), the Lardy's RCR did not change, and Chance's RCR and ADP/O ratio significantly increased, indicating an increase in the coupling of oxidation and phosphorylation processes. At the same time, in the old rat heart mitochondria, calcium ions, even at low concentrations (10-7 mol/l), did not significantly increase the rate of respiration and the ADP/O ratio. 10-5 and 10-4 mol/l Ca2+ resulted in a partial reduction of the activity of the respiratory chain in adult animals and significantly reduced the ADP-stimulated respiration, and the coefficients of RCR after Chance and Lardy in the elderly. +/At also tended to fall. Key words: mitochondria; Ca2+; oxidative phosphorylation; respiratory chain; heart; aging. [ABSTRACT FROM AUTHOR]

We studied the parameters of mitochondrial respiration in the suspension of isolated heart mitochondria from old rats using glutamate and succinate - the substrates for the I and II respiratory chain complexes, as well as the dependence of this process on the action of calcium ions. It was shown that Ca2+ influx dynamics in old rat heart mitochondria is different from that in adult control organelles, and the maximum of fluorescence of the calcium-sensitive dye Fluo-4 AM at Ca2+ concentration 100 μmol/l was observed at 3rd minute and was 27% higher than in the control. Consequently, in older rats, we observed a more sharp increase in intramitochondrial calcium. Despite the moderate increase (using succinate) or no different from that in adult animals (using glutamate) of the V2 indicator in the 24-month rats, ADP-stimulated respiration rate decreased, which led to a decrease in respiratory control ratio (RCR) by Chance and Lardy 1.18 and 1.6 times (with oxidation of succinate) and 1.18 and 1.4 times (in the presence of glutamate). However, the efficiency of phosphorylation of ATP, which is characterized by the ratio of ATP synthesis and oxygen absorption (ADP/O), did not change, nor did the velocity of phosphorylation of ATP (ADP/Δt). The effect of calcium ions on mitochondrial respiration in adult rats was dose dependent. At low concentrations of cation (10-7 mol/l), the Lardy's RCR did not change, and Chance's RCR and ADP/O ratio significantly increased, indicating an increase in the coupling of oxidation and phosphorylation processes. At the same time, in the old rat heart mitochondria, calcium ions, even at low concentrations (10-7 mol/l), did not significantly increase the rate of respiration and the ADP/O ratio. 10-5 and 10-4 mol/l Ca2+ resulted in a partial reduction of the activity of the respiratory chain in adult animals and significantly reduced the ADP-stimulated respiration, and the coefficients of RCR after Chance and Lardy in the elderly. +/Δt also tended to fall. [ABSTRACT FROM AUTHOR]