Functioning of systems of the neutral amino acid transport in enterocyte brush-border membranes of rat small intestine under normal conditions and after ionising radiation.

Peculiarities of neutral amino acid (L-leucine and L-phenylalanine) transport in brush-border membranes of rat small intestine enterocytes under normal conditions and following a 1.0-Gy X-ray irradiation have been studied. The increase of the brush-border membrane permeability for ions and amino acids is considered to be the main reason of the post-irradiation disorders in the transmembrane transport of amino acids. The radiobiological approach made it possible to corroborate the existence of a Na+-dependent L-phenylalanine transport system different from the common system for neutral amino acids.

[The use of nontraditional approaches to the analysis of the effects of radiation on the system of protein phosphorylation in spleen lymphocytes]. / Ispol'zovanie netraditsionnykh podkhodov dlia analiza vliianiia oblucheniia na osobennosti funktsionirovaniia sistem fosforilirovaniia belkov v limfotsitakh selezenki]

Postradiation disturbances in functioning of Ca(2+)- and cyclic nucleotide-dependent protein kinase systems are established. Kinetic index of different protein kinases of spleen lymphocytes under irradiation with doses of 0.5 and 1 Gy are analysed using return-cards-construction and Lyapunov's-coefficient-determination methods. It is shown that determined disturbances can be considered as a part of general unspecific adaptational reaction of lymphocytes to irradiation.

[Effect of ionizing radiation on the structure and functional properties of the basolateral membrane of small intestine enterocytes]. / Vliianie ioniziruiushchei radiatsii na strukturu i funktsional'nye svoistva bazolateral'noi membrany énterotsitov tonkogo kishechnika.

The structural state and transport properties of basolateral membrane of rat small intestine enterocytes after exposure to X-ray irradiation (0.5; 1.0 and 2.0 Gy) were studied. The substantional suppression of the active Ca(2+)-transport process concomitant to versatile changes of the membrane structure involving the surface sites and intramembrane protein-lipid complexes was revealed one day after irradiation. Taking into account the early obtained data on apical membrane functional disorders these results confirm that ionizing radiation in sublethal doses induces the structure-function modification of enterocyte plasma membrane affecting the function of the small intestine epithelial cells.

[Effect of x-irradiation on the properties of cyclic AMP-dependent protein kinases from rat spleen lymphocytes]. / Vliianie rentgenovskogo oblucheniia na svoistva tsAMF-zavisimykh proteinkinaz iz limfotsitov selezenki krys.

It was shown, that in conditions of acute radiation affection in doze 0.5 and 1 Gy, there was a decrease of 32 and 55% in activity of cyclic AMP-dependent protein kinases, isolated from cytosol of lymphocytes. The analysis of cAMP-dependent protein kinases properties has shown, that disturbance in the interaction of the enzyme with protein substrate of phosphotransferase reaction and main modulater enzymes activity--cAMP proceeds of the ionising radiation effect.

[Post-radiation disturbances in the cyclic nucleotide system in rat spleen and thymus lymphocytes]. / Postradiatsionnye narusheniia v sisteme tsiklicheskikh nukeltidov limfotsitov selezenki i timusa krys.

The changes in cAMP and cGMP content in rat spleen and thymus lymphocytes after irradiation in doses of 0.5 and 1 Gy, are determined, indicating to significant disturbances in the system of cyclic nucleotides. Radiation affected the functioning of enzymes both of synthesis and hydrolysis of cAMP and cGMP in spleen lymphocytes. The activity of adenylate cyclase and guanylate cyclase did not change in thymocytes after the exposure, while the activity of phosphodiesterase of cyclic nucleotides slightly increased.

[Release of arachidonate from rat spleen lymphocytes after irradiation]. / Vysvobozhdenie arakhidonata iz limfotsitov selezenki krys posle oblucheniia.

After spleen lymphocytes incubation with 14C-arachidonic acid 14C label was found associated predominantly with phosphatidylethanolamine (PE) and phosphatidylcholine (PC). Addition of 0.5 mkM a 23187 to the incubation media with 2 mM CaCl2 caused a 4-fold increase in release of labeled free arachidonate in lymphocytes of the control animals. A dose-dependent increase in release of free arachidonate and membrane Ca(2+)-dependent phospholipase activity towards exogenous 2-14C-arachidonoyl-PE and -PC take place in a period 6-12 h after animal's irradiation in a doses 0.5 and 1.0 Gy. The maximum arachidonate release in 6h following 1 Gy irradiation correlates with activation of more active phospholipase A2, hydrolyzing PE. Free arachidonate is supposed to be mobilized from different phospholipid pools, depending on the content of Ca2+ in the cells after irradiation.

[Phospholipase A2 in the biochemical mechanisms of spleen lymphocyte reaction to x-ray irradiation of animals]. / Fosfolipaza A2 v biokhimicheskikh mekhanizmakh reaktsii limfotsitov selezenki na rentgenovskoe obluchenie zhivotnykh.

Preincubation of rat splenic lymphocytes with nonspecific mitogens and calcium ionophore A23187 led to the activity of phospholipase A2 which hydrolyzed arachidonoyl phospholipids and to increased cellular levels of free arachidonic acid. The effect of some substances was decreased as follows: A23187 > > lipopolysaccharide > phytohemagglutinin > concanavalin A. Dose-dependent activation of phospholipid hydrolysis and arachidonic acid release were observed within 6-12 hrs after X-ray irradiation of animals in doses of 0.5 and 1.0 Gy. The involvement of phospholipase A2 in deterioration of receptor interactions occurring during transmission of an activation signal in splenic lymphocytes in the early postirradiation period is discussed.

[Second messenger systems and protein kinase activity in rat thymus and liver in the early stages of radiation injury]. / Sistemy vtorichnykh messendzherov i aktivnost' proteinkinaz v timuse i pecheni krys na rannikh étapakh luchevogo porazheniia.

The effect of ionizing radiation (7, 76 Gr) on the content of cyclic nucleotides and Ca2+ ions from rat thymus and liver has been established: it was increased 15, 30 min and 4.6 h and decreased 2, 12 h and 24 h after the irradiation. Changes in activity of cyclic nucleotide-dependent protein kinases and Ca2+, phospholipid-dependent protein kinase correlated with the contents of secondary messengers in the irradiated rats (30 min and 4 h after irradiation) are shown.

[Effects of irradiation on fatty acid structure of membrane lipids of the sarcoplasmic reticulum]. / Deistvie rentgenovskogo izlucheniia na zhirno-kislotnyi sostav lipidov membran sarkoplazmaticheskogo retikuluma.

It has been shown that single local X-irradiation (0.21 C/kg) of the rabbit hind limb in the early period of acute radiation injury (1 and 14 h) causes a decrease in saturation of sarcoplasmic reticulum membrane lipids. It is mainly connected with a decreased saturation of the total fraction of phosphatidyl serine, phosphatidyl inositol and phosphatidyl choline. The above changes can increase permeability of the sarcoplasmic reticulum membranes for Ca(2+)-ion after X-irradiation.

[Phospholipase A2 from rat spleen lymphocytes hydrolyzing arachidonoyl-phospholipids]. / Fosfolipaza A2 limfotsitov selezenki krys, gidrolizuiushchaia arakhidonoil-fosfolipidy.

Phospholipase A2 activity in the postnuclear supernatant of lymphocytes has been studied by measuring 14C arachidonate released from labelled phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) as exogenous substrates. The pH optimum was 7.5-9.0 for PE and 9.0 for PC. Phospholipase A2 was not detected in the presence of 2 mM EGTA. It was optimal with the millimolar calcium concentrations and higher towards PE. Preincubation of lymphocytes with 0.5 M ionophore A-23187 was followed by 2.4 fold stimulation of the phospholipase activity. A stimulatory effect was observed after preincubation of cells with 10 micrograms/ml of phytohemagglutinin, lipopolysaccharide, concanavalin A; it decreased as: lipopolysaccharide greater than phytohemagglutinin greater than concanavalin A. The results obtained have suggested the possibility of existence of different forms of phospholipase A2 in the spleen lymphocytes and participation of the enzyme in the early signalling events.

[The content of cyclic nucleotides, free cytoplasmic Ca2+ and malondialdehyde in the splenic lymphocytes and thymocytes of rats under the action of moderate doses of radiation]. / Soderzhanie tsiklicheskikh nukleotidov, svobodnogo tsitoplazmaticheskogo Ca2+ i malonovogo dial'degida v limfotsitakh selezenki i timotsitakh krys pri deistvii nevysokikh doz radiatsii.

It has been shown that the malonic dialdehyde (MDA) content in spleen lymphocytes of rats increases after whole-body X irradiation with a dose of 0.5 Gy to reach the maximum level in 24 h. Simultaneously, the concentration of cGMP and free cytosol Ca2+ increases. With a dose of 1 Gy MDA content of cells increases 6 h following irradiation. The maximum drop of the release of viable lymphocytes from the spleen and thymus, observed 24 h and 3 days after irradiation respectively, coincides with the appearance of the second peak of the MDA content. The level of cGMP remains decreased throughout the period of about 6 days. The onset of lymphocyte repopulation in the spleen on day 6 coincides with the decrease in the MDA level and increase in the cytosol Ca2+ concentration.

[Lipid peroxidation of rat spleen and thymus lymphocytes treated with x-rays (0-5-1.0 Gy)]. / Perekisnoe okislenie lipidov limfotsitov selezenki i timotsitov krys pri vozdeistvii rentgenovskogo oblucheniia (0.5-1.0 Gr).

It is established, that low doses of X-ray irradiation have affected activation of lipid peroxidation (LPO) in immunocompetent cells of the spleen and thymus. The amount of malonic dialdehyde (MDA) in lymphocytes of spleen and thymocytes increases 2 times twenty-four hours after animals' irradiation by X-rays in a dose of 0.5 Gy; when a dose grows to 1.0 Gy, the MDA content in the spleen lymphocytes increases from the 1st to the 6th days and in thymocytes from the 1st to the 3d days reaching its maximum at the 3d day. MDA accumulation in the immunocompetent cells of irradiated animals varies depending on the method of lipid peroxidation initiation.

[Structural changes in the sarcoplasmic reticulum membrane of skeletal muscles at the early stage of x-ray irradiation]. / Strukturnye izmeneniia membran sarkoplazmaticheskogo retikuluma skeletnykh myshts na rannem étape rentgenovskogo oblucheniia.

A single X-ray irradiation of the rabbit hindlimbs in a dose of 0.24 C/kg evokes a decrease in fluorescence of the ANS probe bound with membranes of the sarcoplasmatic reticulum as a result of the decrease of binding sites, binding constant as well as the quantum output of the probe. A decrease in fluorescence of tryptophan residues of Ca-ATPase localized in membranes and attenuation of interaction of its SH-group with dithionitrobenzoic acid has been also observed at early postradiation terms (1 and 24 h). The obtained results evidence for structural rearrangements occurring in membranes of the sarcoplasmic reticulum under the effect of ionizing radiation. Changes in conformation of CA-ATPase molecules contribute much to this process.

[Increase in free Ca2+ level determined by quin-2 in spleen lymphocytes from irradiated rats]. / Uvelichenie kontsentratsii svobodnogo Ca2+, opredelennoi s pomoshch'iu kvina-2 v limfotsitakh selezenki obluchennykh krys.

The output of lymphocytes, obtained on a ficoll-verografin gradient and intracellular free Ca2+ concentration were studied in the rat spleen 1, 3 and 6 days after X-ray irradiation in a dose of 0.5 Gy. The amount of lymphocytes decreased by 30% a day after irradiation and turned to the control level 3 days after exposure of animals. Free Ca2+ concentration remains abnormally high during all the examined period, increasing to 411 nM a day after irradiation and approaching to the control value 6 days after irradiation.

[The effect of ionizing radiation on Ca 2+-ATPase activity from the sarcoplasmic reticulum of rabbit skeletal muscles]. / Vliianie ioniziruiushchei radiatsii na aktivnost' Ca 2+-ATP-azy sarkoplazmaticheskogo retikuluma skeletnykh myshts krolika.

It is established that a decrease in the Ca2(+)-ATPase activity in the sarcoplasmic reticulum membranes 1 and 24 hours after the local X-ray irradiation of rabbit hind limb by a dose of 0.21 Cl/kg is caused mainly by a change in the enzymic microenvironment and a damage of native protein-lipid interactions essential for the functional activity of Ca2(+)-ATPase.

[Discovery of new sites of CA2+ binding by vesiculated fraction of plasma membranes of the smooth muscle cells in the presence of alameticin]. / Obnaruzhenie novykh uchastkov sviazyvaniia Ca2+ vezikulirovannoi fraktsiei plazmaticheskikh membran gladkomyshechnykh kletok v prisutstvii alametitsina.

A study carried out with plasma membrane vesicular fraction from rabbit intestine smooth muscle demonstrated that a new type of Ca-binding sites with high affinity appear in a Mg2(+)--free medium. Another type of low affinity Ca-binding sites was revealed in ATP-free medium.

[The effect of ionizing radiation on the structure of the hydrophobic fragment of Ca-ATPase in skeletal muscle sarcoplasmic reticulum]. / Vliianie ioniziruiushchei radiatsii na strukturu gidrofobnogo fragmenta Ca-ATFazy sarkoplazmaticheskogo retikuluma skeletnykh myshts.

Early (1 and 24 h) after X-irradiation with a dose of 0.21 C/kg changes occurred in the acceptability of the polypeptide chain parts of sarcoplasmic reticulum Ca-ATPase for the effect of trypsin. The analysis of the results of studying the structural and functional properties of a hydrophobic fragment of this enzyme in the control and after irradiation permitted to define the part of the Ca-ATPase polypeptide chain that provided ion selectivity of the fragment.

[Oxytocin interaction with lipids of artificial and biological membranes]. / Vzaimodeistvie oksitotsina s lipidami iskusstvennykh i biologicheskikh membran.

It is established on the liposomes, lipid and proteolipid monolayers, that the first process of bounding of oxytocin with plasmatic membrane of smooth muscle cells of small intestine is the interaction of hormone molecules with molecules of membrane lipids, adsorption and the instillation of peptide into lipid mono- and bilayer.

[Rat brain catecholamines in the initial period of acute radiation exposure]. / Katekholaminy golovnogo mozga krys v nachal'nyi period ostrogo luchevogo vozdeistviia.

Total X-ray irradiation (0.21 C/kg of rats induces an hour later an increase in the dopamine and norepinephrine content in the grey matter by 11 and 60%, respectively. The spontaneous release of dopamine and norepinephrine from the brain synaptosomes of the irradiated rats falls causing a decrease of the initial rate of the process. Potassium chloride depolarization of synaptosome membranes of the control rat brain increases both the maximal and initial rate of the process of neuromediators' release; in irradiated animals only the maximal rate of the process grows, the initial rate of the dopamine release being unchanged and that of norepinephrine increasing but less that in the control. After irradiation maximal rate of the by synaptosomes dopamine uptake is 2.6 times as high, while that of norepinephrine is 4.6 times as low; Km of the highly specific uptake of norepinephrine decreases.