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Biomedical subjects

Iu A Vladimirov

Publications and source records attributed to Iu A Vladimirov.

At least 19 recordsLinked to original sources
PubMed1977

[Effect of antioxidants and complexons on mitochondrial swelling induced by thyroxine].

The rate of thyroxin-induced swelling of rat liver mitochondria depended but little on the cation compositions of the medium (KCl, NaCl or choline chloride), this indicating that the enhancement of mitochondrial membrane permeability for cations in the presence of thyroxin was of negligible selectivity. The antioxidants alpha-tocopherol and beta-ionol in concentrations completely inhibiting the lipid perioxidation failed to affect the thyroxin-induced mitochondrial swelling; hence the latter could not be attributed to the lipoperoxidation. The kinetics of the swelling and the fact of its inhibition by EGTA imply the necessity of calcium ions in the activation of the process and make possible a postulation that the thyroxin-based mitochondrial swelling was based on the process of activation of the membrane phospholipase in these organellae.

Animals↗
PubMed1977

[Role of mitochondrial membrane lipid hydrolysis in their swelling induced by thyroxine].

The thyroxin-induced mitochondrial swelling was accompanied by an accumulation in organellas of free fatty acids which level was restored after the mitochondria contraction in the ATP presence. EGTA induced mitochondrial contractions as well, but with no free fatty acids utilization. Apparently, the thyroxin-induced mitochondrial swelling is the result of the membrane phospholipase activation and of the increase in the membrane cationic permeability due to the hydrolysis of membrane phospholipids.

Adenosine Triphosphate↗
PubMed1977

[Influence of thyroxine on lipid peroxidation in mitochondrial membranes].

In concentrations above 5.10(-7) M thyroxin brought about a delay in chemifluorescence development and decreased the slope of semilogarythmic plot of chemifluorescence curve at the initial step of the fluorescence slow flash. The antioxidant activity of thyroxin was found to be insignificantly lower than that of the well-known antioxidant alpha-tocopherol. In lower concentrations (about 1.10(-8) M) the hormone can act as prooxidant, the effect being the highest in the case of intact mitochondria incubated in the phosphate-containing medium in the presence of Mg2+ ions, and much less in the mitochondria treated in hypotonic medium containing Ca2+ ions.

Animals↗
PubMed1977

[2 possible mechanisms of action of thyroxine on mitochondrial swelling].

The effect of thyroxin on different types of mitochondrial swelling (induced by calcium, detergents, valinomycine, or lipid peroxidation) was investigated. Under conditions favourable for phospholipase-induced mitochondrial swelling on account of phospholipase activation (low Mg2+ concentration, and Ca2+ present in the incubation medium) the hormone proved to accelerate the swelling of the organellae. When phospholipase-induced mechanism of mitochondrial swelling was inhibited (high Mg2+ concentration) thyroxin depressed considerably the swelling of organellae induced by lipid peroxidation due to its antioxidant action.

Animals↗
PubMedDate not supplied

[Regulation of peroxidation of mitochondrial membrane lipids initiated by Fe2+ ions by antoxidants of the 1,4-dihydropyridine series in experiments in vitro].

Effect of antioxidants on the rate of free radical peroxidation was studied in mitochondria in presence of Fe2+. For this purpose derivatives of 1,4-dihydroxypyridine, their heteroaromatic analogues, NAD-H+ and butyl hydroxytoluene (35 substances) were tested in the system by chemoluminescence. Several 1,4-dihydroxypyridine derivatives were found to be effective reagents in the system and could be compared by the activity with the recognized synthetic antioxidant butyl hydroxytoluene.

Animals↗
PubMedDate not supplied

[Fluorimetric study of phospholipase A-induced efflux of Ca2+ from liposomes].

Artificial vesicles, liposomes, were prepared from the total fraction of phospholipids of rat liver mitochondria. Electron microscopy showed that the structure of liposomes depended on cation composition of the medium in which they were formed. Fluorescence of chlorotetracycline increased in the suspension of liposomes loaded with Ca+2 due to the formation of Ca+2-chlorotetracycline-phospholipid membrane complex. Incubation of liposome suspension with phospholipase A in the presence of EDTA resulted in a decrease of chlorotetracycline fluorescence indicating a break of the integrity of liposome membranes and Ca+2 efflux.

Animals↗
PubMedDate not supplied

[Kinetics of the interaction of ferrous oxide with oxidized lipids and possibility of chiluminescent determination of hydroperoxides].

The theory shows that for lipids containing hydroperoxides of unsaturated fatty acids there exists a verge concentration of Fe2+: at concentrations of Fe2+ lower than the verge one the peroxidation process develops autocatalytically and at higher concentrations it looks pulseshaped. In the second case the amplitude of pulse concentration of peroxide radicals and the square root from the maximum value of chemiluminescence intensity are proportional to the concentration of hydroperoxides present in the system at the time of ferrous ions injection. The former two values do not depend on the concentration of inoxidized fatty acids. In the experiments of chemiluminescence of partially oxidized linoleic acid and lecithin in methanol-benzene solutions (1 : 2) a perfect correlation between the experimental data and theoretical conclusions was revealed.

Ferrous Compounds↗
PubMedDate not supplied

[Distribution of small hydrophobic molecules in membranes. I. Artificial lipid membranes].

A hydrophobic uncharged fluorescent probe of 4-dimethylaminochalcone (DMC) interacted with synthetic phospholipid membranes. Comparison of absorption spectra and fluorescence of DMC in the membranes and organic solvents shows that in the membranes the DMC molecules are located not in the hydrocarbon layer but in the polar regions near the surface. The probe is distributed regularly along the surface forming no dimers and clusters. Polar groups which surround the probe in the membrane are less mobile than the molecules of organic solvents at the same temperature. The evaluation shows that the relaxation time of polar groups in the probe environment is longer than 0.15-10(-9) sec. The DMC molecules may be located in different sites of the membrane surface, which seem to differ from one another in the mobility of polar groups.

Chalcone↗
PubMedDate not supplied

[Permeability of plane bilayer lipid membranes in the presence of sarcoplasmic reticulum vesicles].

Interaction between vesicles of sarcoplasmic reticulum (VSR) and bilayer lipid membranes (BLM) was investigated. VSR were added into the membrane-surrounding solution. For the formation of complex VSR-BLM the surface of BLM was charged positively by adding 10(-6) M acetyltrimethylammonium bromide and the transmembrane electrical potential was applied in the negative direction (the positive direction was chosen from inner section of camera with VSR to outer section). The formation of complex VSR-BLM proceeds via two stages. The second stage is accompanied by the formation of nonselective channels of conductivity, perhaps, aqueous pores.

Electric Conductivity↗
PubMedDate not supplied

[Effect of valinomycin on structural and functional transitions in sarcoplasmic reticulum membranes].

Effect of valinomycin (VAL) on ATPase activity and transport of calcium ions in sarcoplasmic reticulum (SR) vesicles has been studied, as well as the diffusion efflux of calcium ions from liposomes of the total fraction of SR lipids. The studies were carried out in the temperature range of 10 divided by 50 degrees. Changes in the structure of SR membranes were checked with a fluorescent probe of 3-metoxibenzantron. It was shown that at the molar ratios 1:7000-1:70 VAL decreases its ATPase activity and active transport of calcium ions in SR at all temperatures. Besides VAL decreases the rapid efflux of calcium ions from SR and the diffusion efflux of calcium ions from liposomes within the temperature range 10 degrees divided by 35 degrees; it increases the rates of these processes at higher temperatures. Simultaneously the broadening of temperature intervals of structural transitions in the SR membranes takes place.

Adenosine Triphosphatases↗