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Biomedical subjects

V V Lemeshko

Publications and source records attributed to V V Lemeshko.

At least 55 records · Page 3Linked to original sources
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[Structural state of rat liver mitochondrial and microsomal membranes in aging and after treatment with thyroxine].

Rotation mobility of stearic acid spin labelling in mitochondria and microsomes of 24 months old rats is shown to decrease in comparison with that of 1 month rats. This decrease correlates with an increase in the free cholesterol content in membranes. The phospholipid composition is practically unchanged. With age the osmoresistance of organelles decreases and the cryoresistance increases, supporting indirectly the existence of structural changes in membranes with ageing. The most pronounced activation of NADPH-cytochrome C reductase in the microsomal membrane after the treatment with triton X-100 is observed in case of old animals. The thyroxine treatment of old rats causes a "rejuvenative" effect on the structural state of mitochondrial and microsomal membranes, evidencing for the important role of hormonal regulation in mechanisms of their age rearrangement.

Aging↗
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[Variations in ATP synthetase activity of rat liver mitochondria during aging and under the effect of thyroxine].

Experiments with 1-, 3-, 12- and 24-month male rats show a decrease in the rate of ATP synthesis by the liver mitochondria with oxidation of succinate and alpha-glycerophosphate. Administration of thyroxin to animals for 2 and 9 days evokes a more pronounced increase of ATP-synthetase activity in 12- and 24-month rats and an essential decrease of the age differences of the activity. It is suggested that the character of observed variations is caused by age changes in the system of the hormonal metabolism control.

ATP Synthetase Complexes↗
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[Role of the glycerophosphate shunt in regulating oxidation of cytoplasmic NADH and ATP synthesis by liver mitochondria during rat ontogeny].

The activity of alpha-glycerophosphate dehydrogenase rate of alpha-glycerophosphate oxidation and ATP synthesis were determined in the liver mitochondria of 1, 3, 12 and 24-month old rats in norm and two days after thyroxin daily administration in a dose of 0.25 mg per 100 g of body mass. The value of the studied parameters decreases with the age, most considerably--from one to three months and then--from 3 to 24-month age. This evidence for the fact that the role of glycerophosphate shuttle in the energy supply of cells falls with ageing; thyroxin administration evoked almost a two-fold increase of the mentioned parameters in one-month rats and more than three-fold in 12 and 24-month animals. A decrease in the alpha-glycerophosphate dehydrogenase activity with ageing is supposed to be connected with the thyroid gland function.

Adenosine Triphosphatases↗
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[Enzymes of the antioxidant system of rat liver during aging].

It is shown that ageing induces in rats intensification of a GSH-dependent antioxidant effect of the liver cytozole, growth of glutathione-S-transferase activity of cytozole, microsomes and mitochondria, a decrease of the NADPH generation rate in cytozole with malate and glucose-6-phosphate oxidation (the rate remaining at high level with isocytrate oxidation). It is supposed that under definite physiological conditions a lowered rate of NADPH generation in the malate dehydrogenase and glucose-6-phosphate dehydrogenase reactions in old animals may limit the efficiency of the NADPH-GSH-dependent antioxidant system of the liver cells. The peroxidase activity of cytochrome P-450 of microsomes and the glutathione reductase activity (EC 1.6.4.2) of cytozole rise in the liver of rats up to their 12 months and fall considerably with ageing. Cytochrome P-450 in the membranes of endoplasmic reticulum plays the role of an antioxidant.

Aging↗
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[Age variations in ethylmorphine demethylase and benzopyrene hydroxylase activities in rat liver microsomes].

The ethylmorphine demethylase activity of the rat liver microsomes was higher in three-month animals (as compared to one-month), remained at a high level in the 12-month and decreased in old rats. The benzopyrene hydrolase activity increased in three-month animals, decreased in 12-month rats and remained the same with subsequent ageing of the organism. Asynchronicity of variations in the oxidation rate of different xenobiotics with ageing is considered as a result of changes in substrate specificity of the monooxygenase system due to metabolic peculiarities which reflect the age development of the organism and extinction of the reproduction function.

Aging↗
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[Age characteristics of the interaction between fluorescent probes and thyroxine with the membranes of rat liver microsomes].

By means of fluorescent probes, 1-anilino naphthalene-8-sulfonate (ANS), methoxybenzanthrone (MBA) and pyrene, an increase of membrane affinity to ANS, shift of MBA fluorescence maximum to the short-wave spectrum region and a change of the membrane microviscosity were observed in the liver microsome membranes during aging of rats. No significant changes of fluorescent parameters of the probes with rats aging were found in mitochondria. ANS was concurrently displaced by thyroxine, affinity to which significantly increased with aging, and in young animals during hyperthyroidism. The increase of microsome membranes affinity to thyroxine with age is considered as an intracellular mechanism which is involved in the metabolism changes of hypothyroid pattern in rat liver during aging.

Affinity Labels↗
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[Age-related changes in thyroxine regulation of the NADPH-dependent oxidative system in rat liver microsomes].

Age peculiarities of the thyroxin effect on oxidative microsome system are manifested at the level of different links of NADPH-dependent chain of electron transfer and are most pronounced relative to changes in the content of cytochrome P-450 and demethylase activity, which get considerably reduced with hyperthyrosis in the middle age. The aniline hydroxylase activity somehow increases with hyperthyrosis in young immature animals and is practically unchanged in adult and old ones. It is supposed that age peculiarities of the thyroid hormone action on the oxidation system in microsomes are determined to a consideralble extent by the level of androgens and depend on age changes in the reproductive function of the organism.

Aging↗
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[Activation of membrane lipid peroxidation in the liver of young and old rats by thyroxine and actinomycin D].

Thyroxine and actinomycin D evoke activation of enzymatic peroxide oxidation of membrane lipids in the liver mitochondria and microsomes 24 hours after their separate or combined administration to Wistar males rats. In young animals the thyroxine effect is less pronounced than in old ones. Activation of peroxidation of membrane lipids with thyroxine or actinomycin D is not additive. Thyroxine had no essential influence on the glutathione-S-transferase activity of mitochondrial and postmitochondrial fractions of liver homogenates which is higher in old animals.

Aging↗
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[Age characteristics of lipid peroxide oxidation induction in the rat liver during fasting].

The peroxide oxidation of lipids, both spontaneous and NADPH-induced, was studied in incubation of the liver homogenate postnuclear fraction for rats aged 1, 3, 12 and 24 months. Fasting increases significantly the rate of NADPH-dependent accumulation of malonic dialdehyde, the absolute growth value of which was almost the same in 1,3 and 24-month rats and higher than in the middle-aged animals. A relative increase in the lipid peroxide oxidation intensity during fasting as compared to the norm is more sharply pronounced in old rats.

Aging↗
PubMedDate not supplied

[Age-related characteristics of thyroxine action on the cytochrome content in rat liver mitochondria and on body weight].

Content of cytochromes a (a3) was decreased and the ratio c/a/a3/ was increased in rat liver mitochondria depending on animal age. Administration of thyroxine incresased the level of cytochromes. These phenomena were especially distinct in 12- and 24-month old rats. The latent period, manifested as a decrease in body mass, was the characteristic property of the tyroxine effect in the young animals. Age differences in the effect of thyroxine depend also on the dose of the hormone.

Aging↗