[Role of lipid composition in the kinetics of free radical lipid oxidation in photoreceptor membranes]. / O roli lipidnogo sostava v kinetike svobodnoradikal'nogo okisleniia lipidov v membranakh fotoretseptorov.

The initial rate of lipid peroxidation (LPO) in photoreceptor membranes (PRM) of walleye pollock is 1.8--2.3 times higher than in frog PRM. Rhodopsin bleaching leads to an increase of LPO initial rate in PRM while having no effect on LPO in walleye pollack PRM. The content of unsaturated fatty acids in walleye pollock PRM is 1.4 times greater than in frog PRM. It is suggested that differences in LPO kinetics in PRM of walleye pollack and frog are caused by the differences in the lipid composition of the membranes (primarily by a high level of phospholipid molecular species with two unsaturated fatty acid residues in walleye pollock retina rod outer segments).

[Fatty acid composition of aminophospholipids of the protein microenvironment in synaptosome plasma membranes in the rat brain]. / Zhirnokislotnyi sostav aminofosfolipidov mikrookruzheniia belkov v plazmaticheskikh membranakh sinaptosom mozga krysy.

Fatty acid composition of the aminophospholipids present in protein microenvironment of the plasmatic synaptic membranes was studied by covalent binding method. The analysis of fatty acids was carried out by gas liquid chromatography. Aminophospholipid fatty acids in the protein microenvironment were found to be more unsaturated compared to the lipids of the free bilayer. The fatty acids of the aminophospholipids present in the protein microenvironment of the plasmatic synaptic membranes were compared to those of rhodopsin microenvironment in photoreceptor membrane. The obtained results are discussed from the point of view of the signal transmission in the excitable membranes.

[Temperature decolorization of the rhodopsin of bulls and Theragra chalcogramma fish]. / Temperaturnoe obestsvechivanie rodopsinov ryby Theragra chalcogramma i byka

It has been demonstrated that fish rhodopsin is less resistant to thermal treatment and it is more readily bleached as compared to bovine rhodopsin. At 18 degrees C, the stability of both rhodopsins decreased in the following sequence: fragments of the outer segments--digitonin extracts-triton X-100 extracts-cetyltrimethylammonium bromide extracts-At higher temperatures (47-56 degrees), this sequence was the following: fragments of the outer segments-digitonin extracts-cetyltrimethylammonium bromide extracts-triton X-100 extracts. Kinetic and thermodynamic parameters (k, Ea, deltaH, delta S*, delta F*) of rhodopsin bleaching at high temperatures were calculated. It is suggested that at 18 degrees C rhodopsin bleaching includes two steps. Possible causes of idfferent stability of the investigated rhodopsins are discussed.

[Fatty acid composition of the bilayer phospholipids in the photoreceptor membranes and aminophospholipids from the rhodopsin microenvironment of warm-blooded and cold-blooded vertebrates]. / Zhirnokislotnyi sostav fosfolipidov bisloia fotoretseptornykh membran i aminofosfolipidov mikrookruzheniia rodopsina teplokrovnykh i kholodnokrovnykh pozvonochnykh.

Studies have been made on the distribution of phospholipids between rhodopsin and free lipids of photoreceptor membranes of the outer segments of retinal rods from cattle, frog Rana temporaria and fish Teragra chalcogramma. comparative investigation of fatty acid composition of phospholipids from rhodopsin microboundary and lipid bilayer in photoreceptor membranes was made as well. Amino phospholipids from rhodopsin microboundry were revealed using glutaraldehyde. This reagent by means of its aldehyde groups links phospholipid amino groups with amino groups of proteins of photoreceptor membranes. After this treatment, free phospholipids of lipid bilayer were extracted from photoreceptor membranes by methanol-chloroform mixture. It was demonstrated that fatty acid composition of phospholipids of lipid bilayer differs from that of amino phospholipids from rhodopsin microboundary. In the animals investigated, fatty acids of phospholipids from lipid bilayer were found to be more unsaturated than fatty acids of amino phospholipids from rhodopsin microboundary. This difference was more pronounced in photoreceptor membranes from the frog and fish than from cattle.

[Mechanisms of the initiation of lipid peroxidation in the synaptosomes of marine teleosts]. / Issledovanie mekhanizmov initsiirovaniia perekisnogo okisleniia lipidov v sinaptosomakh morskikh kostistykh ryb.

The initial rates of NAD- and NADPH-dependent enzymic and Fe+-ascorbic acid-dependent nonenzymic lipid peroxidation have been measured in synaptosomes from the brain of 4 teleost species. The rates of peroxidation were compared with lipid composition and fatty acid composition of total lipids in order to reveal factors accounting for the intensity of peroxidation in the excitable membranes from the brain of ectotherms. The data obtained indicate that the rates of enzymic lipid peroxidation do not correlate with lipid and fatty acid compositions, depending on the efficiency of production of oxygen in the active form by pyridine nucleotide-dependent enzymic systems. Activation of lipid peroxidation during adaptation of animals to the environment may be considered as one of the mechanisms which account for compensatory changes in fatty acid composition of the membrane lipids.

[Is a change in the microviscosity and asymmetrical distribution of phospholipids in the membrane a necessary condition for signal transmission? A comparison of the mechanisms of signal transmission in the plasma membranes of the brain synaptosomes and retinal photoreceptor membranes]. / Iavliaetsia li izmenenie mikroviazkosti i asimmetrichnoe raspredelenie fosfolipidov v membrane obiazatel'nym usloviem peredachi signala? Sopostavlenie mekhanizmov peredachi signala v plazmaticheskikh membranakh sinaptosom mozga i fotoretseptornykh membranakh stechatki.

The localization of amino phospholipids (phosphatidyl ethanolamine, phosphatidyl serine) and their fatty acid composition in the outer and inner monolayers of plasma membranes from rat brain synaptosomes and retinal photoreceptors in the fish Theragra chalcograma have been studied by chemical modification. The mobility of the lipid components of these membranes was investigated by fluorescent and EPR spin probing techniques after transformation of outer (chemical and physical) signals. The data obtained are discussed in terms of molecular organization of the lipids and of the changes in the mobility of the lipid components of plasma membranes from brain synaptosomes and retinal photoreceptors during transmembrane transmission of the signal.

[The repair of the membrane lipid bilayer in oxidative stress: phosphatidylethanolamine reacylation in synaptosome, photoreceptor and erythrocyte membranes]. / Reparatsiia lipidnogo biosloia membran pri okislitel'nom stresse: reatsilirovanie fosfatidilétanolamina v membranakh sinaptosom, fotoretseptorov i éritrotsitov.

The participation of unsaturated (linoleic and arachidonic) and saturated (palmitic) fatty acids in reacylation of phosphatidylethanolamine (PE) in synaptosomes, photoreceptor membranes and erythrocytes at oxidative stress was studied. Induction of lipid peroxidation (LPO) was found to result in a significant decrease in the content of PE polyenoic fatty acids due to their oxidative destruction. It might be related to both an activation of phospholipase A2 and a decrease in PE reacylation rate. On contrary, under the same conditions an increase in incorporation of palmitic acid into PE was observed. The results of this study suggest that phospholipid deacylation-reacylation reactions comprise an important mechanism of both protection and adaptation of organisms to oxidative stress.

[Structural stabilization of lipids and visual pigment rhodopsin in the photoreceptor membrane by vitamin E]. / Strukturnaia stabilizatsiia lipidov i zritel'nogo pigmenta rodopsina v fotoretseptornoi membrane vitaminom E.

Interaction of alpha-tocopherol with free fatty acids in bovine retinal photoreceptor membranes was studied using ESR spin-probe technique and measurements of rhodopsin thermal denaturation rates. Exogenous alpha-tocopherol incorporated into photoreceptor membranes prevented thermal destabilization of rhodopsin caused by free fatty acids. The efficiency of the stabilizing action of alpha-tocopherol directly depended both on the chain length and the degree of fatty acid unsaturation.

[Regulating and disturbing effects of alpha-tocopherol on lipid bilayers]. / Uporiadochivaiushchee i razuporiadyvaiushchee deistvie alpha-tokoferola na lipidnye bisloi.

Using the high resolution 1H-NMR spectroscopy and spin-probes the influence of alpha-tocopherol on lipid bilayer microviscosity has been studied. It has been established that alpha-tocopherol shows the cholesterol-like action on the physical state of lipid bilayer: alpha-tocopherol increase microviscosity of unsaturated bilayers and decrease microviscosity of saturated bilayers. The character of alpha-tocopherol action is determined by the fatty acidic lipid composition but does not depend on the polar group structure of phospholipid molecule as cholesterol-like action of alpha-tocopherol is found itself in liposomes prepared both from phosphatidylcholine and phosphatidylethanolamine. Analog of alpha-tocopherol without phytol chain 2,2,5,7,8-penthamethyl-6-oxychroman does not show the cholesterol-like action as it is not able to disorder the saturated bilayers.

[Ganglioside-dependent factor inhibiting lipid peroxidation in synaptosomal membranes]. / Gangliozidzavisimyi faktor, ingibiruiushchii perekisnoe okislenie lipidov v membranakh sinaptosom.

The inhibitory effect of exogenous monosialoganglioside GM1 on lipid peroxidation was studied in synaptosomal membranes from rat brain. When this effect was studied over a wide GM1 concentration range, the biphasic kinetics was observed, the highest per cent of inhibition (70%) was found at GM1 concentration of 10(-9)- 10(-8) M. In liposomes made from lipids isolated from rat synaptosomal membranes the inhibition of lipid peroxidation by exogenous GM1 was much less pronounced (25% at maximum) it reached the saturation at ganglioside concentration of 10(-8)-10(-6) M. The thermal denaturation (90 degrees C), storage at 0 degrees C, addition of polymyxin B result in considerable decrease of inhibitory effect of GM1 on lipid peroxidation in synaptosomal membranes. On the contrary phorbol-12-myristate-13-acetate (10(-6)M) or Ca2+ (2.10(-3)M) inhibit lipid peroxidation in synaptosomal membranes, the presence of exogenous GM1 in incubation medium having additional inhibitory effect. Possible mechanisms of ganglioside participation in regulation of functional activity of excitatory membranes are discussed.

[Lipid asymmetry and alpha-tocopherol distribution in outer and inner monolayers of bilayer lipid membranes]. / Asimmetriia lipidov i raspredelenie alfa-tokoferola v naruzhnom i vnutrennem monosloe bisloinykh lipidnykh membran.

Using chemical modification of aminophospholipids (phosphatidylethanolamine, PEA; phosphatidylserin, PS), the location of these phospholipids and their fatty acids has been studied in the inner and outer monolayers of unilayer liposomes. It has been shown that both PEA and PS were located predominantly in the inner monolayer and contained most of the polyenoic fatty acid residues. alpha-tocopherol incorporated into these liposomes was also located predominantly in the inner monolayers. In the liposomes, prepared from a single phospholipid (dioleoylphosphatidylcholine) no asymmetrical distribution of incorporated alpha-tocopherol was observed.

[Transbilayer distribution of alpha-tocopherol and lipid asymmetry in nerve tissue membranes]. / Transbisloinoe raspredelenie alpha-tokoferola i asimmetriia lipidov v membranakh nervnoi tkani.

The alpha-tocopherol content and fatty acid composition of lipids in various types of nervous tissue membranes were studied. The transbilayer distribution of alpha-tocopherol and polyunsaturated fatty acids in liposomes and plasma membranes of synaptosomes was examined. It was shown that both phosphatidylethanolamine and phosphatidylserine are localized predominantly in the inner monolayer and they contain the bulk of polyenoic fatty acid residues. alpha-Tocopherol incorporated into liposomes from synaptosome plasma membrane lipids and present in synaptosome plasma membranes is also predominantly localized in the inner monolayers. No asymmetrical distribution of incorporated alpha-tocopherol was observed in liposomes prepared from a single phospholipid, e.g., dioleoylphosphatidylcholine.

[Some features of rhodopsin regeneration process in the presence of exogenous 11Z-retinal in teleosts]. / O nekotorykh osobennostiakh pritsessa Regeneratsii podopsina morskikh kostistykh ryb v prisutstvii ekzogennogo 11Z-retinalia.

The rate of rhodopsin regeneration in decolorized rod outer segments ROS of pollock and ruff in the presence of exogenous 11Z-retinal is found to depend slightly on the temperature. The Arrhenius curve is linear within 0--20 degrees C and 0--30 degrees C in case of pollock and black ruff ROS respectively. The increase of the regeneration temperature above the upper limit results in both cases in the decrease of the chromophore binding rate due to the temperature denaturation of fish opsin. The rate of opsin regeneration in bovine ROS is temperature-dependent within 0--50 degrees C, the Arrhenius curves having a specific break with the temperature conversion at 12--13 degrees, which indicates a different 11Z-retinal binding rate with bovine opsin at low and high temperatures. Maximal rhodopsin regeneration temperature was observed within 5--10 min. for fish ROS and 1.5 hour for bovine ROS. Trimethylcyclohexene derivatives with a side chain of about 7 carbon atoms and 13Z-retinal competitively inhibited the rhodopsin regeneration in pollock and bovine ROS, while 13E-11, 12-dehydroretinal and all-E-retinal did not effect this process. Some peculiarities of the rhodopsin regeneration process in fish are discussed in connection with the molecular organization of a lipid phase of photoreceptor membrane and chromophore-binding region.

[The antioxidant prevention of disorders in calcium ion metabolism under the action of glutamate on the synaptosomes of the rat cerebral cortex]. / Predotvrashchenie antioksidantami narushenii obmena ionov kal'tsiia pri deistvii glutamata na sinaptosomy kory mozga krys.

An increase of intracellular calcium ion concentration and of the 45Ca2+ entry, a decrease in Na+,K(+)-ATPase activity, and activation of Na+/Ca2+ exchange were shown to be initiated by glutamate in the rat brain cortex synaptosomes. These effects could be prevented with antagonists and blocking agents of the NMDA receptors. Pre-incubation of the synaptosomes with alpha-tocopherol, superoxide dismutase, and ganglioside GM1 was shown to normalise [45Ca2+], the rate of 45Ca2+ entry, and the activity of Na+,K(+)-ATPase in the synaptosomes. The data obtained suggest that calcium ions entering the brain cortex neurones via the NMDA receptors in presence of excessive glutamate, trigger activation of free radical reactions damaging the neurones in ischemia, cerebral lesions, and other pathological conditions.