[Effect of per os administration of dihydroquercetin aqueous form on energy exchange in blood lymphocytes of rats with experimental cardiomyopathy]

Cardiomyopathies are among the most severe myocardial pathologies, which are characterized by resistance to therapy and high mortality due to increasing heart failure and arrhythmia. Cardiomyocyte pathological changes upon cardiomyopathies are associated with mitochondrial dysfunction, leading to excessive formation of reactive oxygen species and the development of oxidative stress. In this regard, the study of the therapeutic potential of antioxidants in cardiomyopathies, as well as the mechanisms of their action on the functioning of mitochondria, is relevant and of high practical importance. The aim of this study was to determine the effect of oral 14-day administration of dihydroquercetin in a water-soluble form (DHQWF) on the activity of the key marker of mitochondrial respiration [succinate dehydrogenase (SDH)] and the cytoplasmic marker of glycolysis [lactate dehydrogenase (LDH)] in blood lymphocytes, as well as on the serum level of lipid peroxidation (LPO) in control rats and rats with experimental cardiomyopathy. Material and methods. Adult male Wistar rats (body weight 220-240 g) were used for the study. Isoprenaline hydrochloride was used to induce cardiomyopathy (IIC) in animals (twice subcutaneous injection at a dose of 150 mg/kg body weight, with a break of 24 hours). DHQ-WF was added to the drinking water for 14 days at the dose of 15 or 30 mg/kg body weight. SDH and LDH activity in lymphocytes was measured using a highly sensitive cytobiochemical method on a blood smear according to the reduction of nitrotetrazolium blue chloride to diformazan of dark blue color. The content of malone dialdehyde (MDA) in the blood serum, heart and liver mitochondria was determined spectrophotometrically using thiobarbituric acid. Mitochondria were isolated from rat tissues by the conventional method of differential centrifugation. Mitochondrial respiration was recorded using a polarographic method. Results. Experimental cardiomyopathy in rats was accompanied by a twofold increase in blood serum MDA level, as well as by a significant increase in SDH and LDH activity in blood lymphocytes. The oral administration of DHQ-WF in cardiomyopathy at a dose of 15 mg/kg body weight led to a significant decrease in serum MDA level, but did not reduce the activity of SDH and LDH in blood lymphocytes, compared with animals with cardiomyopathy that did not receive DHQ-WF. In the control group of animals, the use of DHQ-WF at a dose of 15 mg/kg body weight significantly increased blood lymphocyte LDH activity, but did not have a statistically significant effect on SDH activity and the parameters of mitochondrial respiration and oxidative phosphorylation, the level of MDA in heart and liver mitochondria. Increasing the dose of DHQ-WF administered to 30 mg/kg had less effect on changes in these parameters in control animals. Conclusion. The data obtained indicate that in experimental cardiomyopathy in rats, the course application of DHQ-WF at a dose of 15 mg/kg of body weight acts as an effective antioxidant that prevents the development of lipid peroxidation in blood serum, and can modulate energy metabolism towards the enhancement of glycolysis in blood lymphocytes in control animals.

Effect of hypoxia on mitochondrial enzymes and ultrastructure in the brain cortex of rats with different tolerance to oxygen shortage

The mitochondrial structure and the contents of subunits (NDUFV2, SDHA, Cyt b, COX1) of mitochondrial respiratory complexes I-IV as well as of the hypoxia-inducible factor (HIF-1α) in the brain cortex (BC) of rats with high resistance (HR) and low resistance (LR) to hypoxia were studied for the first time depending on the severity of hypoxia. Different regimes of 30-min hypobaric hypoxia (pO₂ 14, 10, and 8%) were used. It was found that cortical mitochondria responded to 30-min hypobaric hypoxia of different severity with typical and progressing changes in mitochondrial structure and function of mitochondrial enzymes. Under 14 and 10% hypoxia, animals developed compensatory structural and metabolic responses aimed at supporting the cell energy homeostasis. Consequently, these hypoxia regimes can be used for treatment in pressure chambers. At the same time, decreasing the oxygen concentration in the inhaled air to 8% led to the appearance of destructive processes in brain mitochondria. The features of mitochondrial ultrastructure and the function of respiratory enzymes in the BC of HR and LR rats exposed to normoxic and hypoxic conditions suggest that the two types of animals had two essentially distinct functional and metabolic patterns determined by different efficiency of the energy apparatus. The development of adaptive and destructive responses involved different metabolic pathways of the oxidation of energy substrates and different efficiency of the functioning of mitochondrial respiratory carriers.

Uridine as a protector against hypoxia-induced lung injury

The effect of the activation of the mitochondrial ATP-dependent potassium channel (mitoKATP) on the ultrastructure of rat lung in acute hypoxic hypoxia (7% of oxygen in nitrogen, exposure 30 min) was studied. It was shown that uridine, a precursor of the mitoKATP activator UDP, exerted a protective effect against hypoxic damage to the lung. The administration of uridine to animals prior to hypoxia decreased the number of mitochondria with altered ultrastructure and prevented the hypoxia-induced mitochondrial swelling. Uridine also protected the epithelial, interstitial and endothelial layers of the air-blood barrier from the hypoxia-induced hyperhydration. The protective action of uridine against hypoxia-induced lung injury was eliminated by the selective blocker of mitoKATP 5-hydroxydecanoate. These data suggest that one of the mechanisms of the positive effect of uridine is related to the activation of the mitoKATP channel, which, according to the literature and our data, is involved in the protection of tissues from hypoxia and leads to adaptation to it. A possible role of uridine in the maintenance of the mitochondrial structure upon hypoxia-induced lung injury and the optimization of oxygen supply of the organism is discussed.