[Comparative characteristics of tRNA-methyltransferases from rabbit liver and myocardium under normal conditions and in experimental ischemia]. / Sravnitel'nye kharakteristiki tRNK-metiltransferaz pecheni i miokarda krolikov v norme i pri éksperimental'noi ishemii.

Comparative studies of the state of aggregation and activity of tRNA-methyltransferases in cytosol (105,000 X g supernatant) from normal and ischemic rabbit liver and myocardium were carried out. The optimal conditions (pH, protein concentration, ionic composition of incubation mixture) for the determination of activity of tRNA-methyltransferases were elaborated. The protein fraction precipitated at 55% saturation of ammonium sulfate was shown to inherit the highest activity of tRNA-methyltransferases. In rabbit liver cytosol, the bulk of the tRNA-methyltransferase activity (approximately 50%) was found to be associated with high molecular weight complexes containing aminoacyl-tRNA-synthetases. The tRNA-methyltransferase activity was increased almost 1.4-fold both in the myocardium cytosol under total ischemia of isolated heart (30 min, 37 degrees C) and in liver cytosol under experimental myocardial infarction (EMI, occlusion of anterior coronary artery for 12 hours). Moreover, the labilization of high molecular weight complexes was observed: up to 80% of the tRNA-methyltransferase activity was localized in the fraction of lower molecular weight complexes and free enzyme fraction. In the total set of eight methylated nucleotides (products of submethylated tRNA methylation by liver enzymes), the decreased m1A content and the increased m7G and m1G contents were observed at EMI. It was assumed that the observed changes in the state of aggregation of tRNA-methyltransferases, in particular, their dissociation from the high molecular weight amino-acyl-tRNA-synthetase complexes are prerequisites for the suppression of protein biosynthesis under ischemic conditions.

[Functional changes in the mitochondrial site of adenylate kinase and creatine kinase systems of energy transport induced by myocardial ischemia and adriablastin]. / Funktsional'nye izmeneniia mitokhondrial'nogo uchastka adenilatkinaznoi i kreatinkinaznoi sistem transporta énergii pod vliianiem ishemii miokarda i adriablastina.

Under effects of myocardial ischemia (30 min), the activities of the intermembrane enzymes of rabbit heart mitochondria, i.e., adenylate kinase and creatine kinase, are inhibited by 20% and 23%, respectively. Consequently, the creatine- and AMP-activated respiration of mitochondria diminishes by 52% and 39%, respectively. An inhibitory analysis of ADP-, AMP- and creatine-activated mitochondrial respiration performed in the presence of atractyloside has demonstrated that ischemia (30 min), adriblastin (0.688 mM) and succinate (10 mM) cause alterations in the functional coupling of adenylate kinase and creatine kinase with the adenine nucleotide translocator. These alterations lead to the diminution of the rate and efficiency of energy transfer from mitochondria to hexokinase, as an arbitrary site of energy consumption. An addition of cytochrome c to ischemic heart mitochondria results in an increase in the rate of ATP synthesis; however, the efficiency of this process is lowered. The toxic effect of the anticancer drug--adriblastin on heart mitochondria respiration is enhanced in the presence of creatine in the bathing solution.

[Evaluation of structuro-functional heterogeneity of isolated mitochondria from the normal and the ischemic myocardium]. / Otsenka strukturno-funktsional'noi geterogennosti izolirovannykh mitokhondrii normal'nogo i ishemicheskogo miokarda.

The structural and functional heterogeneity of mitochondria isolated from intact and ischemic (after 60 min exposure at 37 degrees C) rabbit myocardium was evaluated. In the presence of cytochrome c. a relatively high (260 +/- 26 ng at O/min . mg of protein) rate of rotenone-sensitive NADH oxidation was observed, which was increased in ischemia. Cytochrome c stimulated the increase of NADH oxidation in mitochondria of normal and ischemic myocardium by the factors of 3.5 and 3.4, respectively. Succinate oxidation in the presence of bromthymol blue in normal and ischemic myocardium mitochondria was activated by cytochrome c 3.3- and 2.9-fold, respectively. The percentage of mitochondria with both structurally damaged membranes was 15% and 25% in normal and ischemic myocardium preparations, respectively. In the absence of ADP, cytochrome c contributed to the increase of the succinate oxidase activity in ischemic mitochondria; that in the 3rd state was inhibited in ischemia and normalized by cytochrome c. A principle was proposed for estimating the percentage of mitochondria with damaged outer membranes, the indices being equal to 34% in control and to 56% in ischemic myocardium. Evidence was obtained suggesting that this mitochondrial fraction was characterized by lowered coupling and absence of rotenone-sensitive NADH: oxidase activity. The percentage of intact mitochondria, in which succinate oxidation is inhibited by bromthymol blue and does not need exogenous cytochrome c, is 51% in control and 19% in ischemic myocardium mitochondria.

[Effect of energy metabolism inhibitors on the morphometric parameters and 3-dimensional structure of L-cell mitochondria]. / Vliianie ingibitorov énergeticheskogo obmena na morfometricheskie parametry i prostranstvennuiu strukturu mitokhondrii L-kletok.

It has been shown by stereological analysis that the earlier discovered changes in the structure of mitochondria in cyanide treated L-cells (decrease in numerical density of mitochondria, increase in volume density of mitochondria, and surface density of mitochondrial membranes) are prevented by oligomycin, and they do not occur in the presence of oligomycin and protonophorous uncoupler carbonylcyanide m-chlorphenyl hydrazone applied separately. Proceeding from three-dimension reconstructed mitochondrial models it has been shown that cyanide treatment of L-cells for 23 hours causes a transformation of mitochondria as discrete column-like structures into a network of mitochondrial reticulum oriented from the nucleus to the periphery of the cell. After the treatment of L-cells with cyanide together with oligomycin, or with oligomycin and protonophore applied separately, the mitochondria retain the structure of discrete column-like for mations characteristic of the control cells. It is assumed that the functioning ATP-system is a physiological prerequisite of the formation of mitochondrial reticulum under conditions of the inhibited respiratory energy metabolism in the cell.

[Structural changes in L-cell mitochondria exposed to cyanide]. / Izmeneniia struktury mitokhondrii L-kletok pri deistvii tsianida.

Using light and electron microscopy, as well as stereological analysis, a study was made of structural changes in mitochondria of cultured L-cells acted upon with 1 mM cyanide. After 23 hours of incubation, in cells cultured in the presence of cyanide the volume density of mitochondria, the volume of the average mitochondrion and the surface area of its membranes increased nearly twice as much. Concurrently, the number of mitochondria decrease also practically two-fold without any reliable changes in the surface area of membranes per unit of mitochondrion volume. A shorter (7 hours) incubation of L-cells in the presence of cyanide results in a decreased volume density of mitochondria in the cytoplasm, decreased volume of the average mitochondrion, without any significant changes in other above mentioned parameters. It is supposed that the changes in mitochondria under a prolonged cyanide treatment of cells are conditioned by the fusion of mitochondria as well as by a compensatory increase in the total surface of mitochondrial membranes.

[Effect of prostaglandin E2 on energy metabolism in isolated rat liver mitochondria]. / Vliianie prostaglandina E2 na énergeticheskie parametry izolirovannykh mitokhondrii pecheni krysy.

Prostaglandin E2 at concentrations of 5.6 mM and 56 mM, in presence of EDTA 2.2 mM, did not affect the patterns of respiration and coupling, registered by means of polarographic procedure, in isolated rat liver mitochondria. Activation of phosphorylating and uncoupled respiration of mitochondria was noted in incubation mixtures containing EDTA 2.2 microM, Ca2+ 0.2 microM, prostaglandin E2 5.6 microM. In absence of EDTA prostaglandin E2, at concentrations of 5.6 microM and 56 microM, caused uncoupling of the oxidative phosphorylation and in presence of Ca2+--it caused uncoupling and inhibition of mitochondrial respiration, decrease in the rate of phosphorylation and in the ATPase reaction was well as in the efficiency of mitochondrial proton pump, connected with Ca2+ transport. At concentrations 2.8 microM, 5.6 microM, 14 microM protaglandin E2 increased the proton conductivity of the mitochondrial membrane in presence of K+ and valinomycine. The data obtained suggest that the effect of prostaglandin E2 on the energy functions of mitochondria depends on presence of Ca2+ in the incubation mixture.

[Effect of acetylsalicylic and 2,3-dihydroxybenzoic acids on liver mitochondrial respiration in rats]. / Vliianie atsetilsalitsilovoi i 2,3-dioksibenzoinoi kislot na dykhanie mitokhondrii pecheni krys

Acetylsalicylate (2-5 mM) inhibited phosphorylating (condition III) and uncoupled respiration of rat liver mitochondria in vitro, when succinate and glutamate were used as substrates of oxidation. Lower concentrations of acetylsalicylate did not cause the uncoupling effect. Antirheumatic drug 2,3-dihydroxybenzoate activated the phosphorylation in mitochondria, if it was added up to concentrations of 0.5-5.0 mM for succinate and 0.5 mM for glutamate. An increase of 2,3-dihydroxybenzoate concentration was accompanied by gradual inhibition of phosphorylating and uncoupled oxidation of succinate; activation of the respiration was completely abolished by addition of ADP, DNP and 2,3-dihydroxybenzoate (20 mM). The data obtained suggest that the uncoupling effect of salicylate, which is formed by hydrolysis of acetylsalicylate in the organism, might be responsible for the toxic effect of the latter.

[Electrogenic function of submitochondrial particles at the water-octane interphases]. / Elektrogennaia funktsiia submitokhondrial'nykh chastits na granitse razdela faz oktan/voda.

Studies on submitochondrial particles (SMP) preparation showed that in the sourse of the redox reactions at the octane-water interface, catalyzed by SMP enzymes, the charges are transferred from the aqueous to the octane phase. The effects were detected by a shift of the Volta potential, using the vibrating electrode method. In the presence of 2-N-methyl-amino-1,4-naphthoquinone in octane, acting as electron acceptor, the negative charges were transferred from water to octane following the oxidation of NADH, succinate and ascorbate. The charging of the octane phase was sensitive to the inhibitors of the respiratory chain, e. g. rotenone, antimycin and cyanide. In the presence of 2,4-DNP in octane, acting as a proton acceptor, the oxidation of NADH and succinate by ferricyanide, catalyzed by CMP in the presence of antimycin and cyanide correspondingly, was followed by a transfer of positive charges from water to octane. The positive charging of the octane phase, coupled with NADH oxidation, was found insensitive to rotenone, and that coupled with succinate oxidation, was completely inhibited by antimycin. The positive charging of the octane phase was also observed during the reverse transhydrogenase reaction, catalyzed by SMP at the division of the phases. The effect was inhibited by palmitoyl-CoA.

[Halidor, 1-benzyl-1-(3'-dimethylaminopropoxy)-cyclohep tane fumarate as an uncoupler and inhibitor of the respiratory chain]. / Galidor, 1-benzil-1-(3'-dimetilaminopropoksi)-tsiklogeptanfumarat, kak razobshchitel' i ingibitor dykhatel'noi tsepi

Halidor 1-benzyl-1-(3'-dimethylaminopropoxy)-cycloheptane fumarate, activates succinate oxidation in mitochondria and inhibits reverse electron transport from succinate to NAD+ in submitochondrial partides preparations at doses of 2-10(-5)--10(-3) M. At a dose of 5--7-10(-4) M halidor cause a swelling of mitochondria incubated in 0.1 M NH4NO3. At higher concentrations (10(-3)--10(-2) M) halidor practically completely inhibits NADH and succinate oxidase activity of mitochondria and submitochondrial particles. It is suggested that vasodilating effect of halidor is due to the uncoupling of oxidative phosphorylation, thus causing a deficiency of ATP for contracting function of blood vessel muscles.

[Cytochromes b in submitochondrial particles from beef heart in the presence of redox succinate/fumarate buffer]. / Issledovanie tsitokhromov b v submitokhondrial'nykh chastitsakh serdtsa byka v prisutstvii okislitel'no-vosstanovitel'nogo bufera suktinat/fumarat

Aerobic red-ox titration of cytochromes b from submitochondrial particles (SMP) using red-ox succinate/fumarate couple revealed two components, one of them having E'0=80 mv; n=1 and alpha-band absorption maximum at 562 nm (b562); and the other-E'0=-25 mv; n=1 and the absorption maximum at 565 nm. Energisation of SMP, equilibrated with red-ox succinate/fumarate buffer, brought about a increase in absorption at the cytochromes b region (564-565 nm), which was reversed and prevented by an uncoupler. Energy-dependent reverse electrone transport from ascorbate+TMPD resulted in considerable higher reduction of cytochromes b with summary maximum at 563 nm with the same initial reduction level prior to energisation. The data obtained show that energy dependent reduction of cytochromes b of SMP poised with succinate/fumarate red-ox buffer is presumably to the effect of energisation on the red-ox state of cytochrome b566. It is suggested that the transmembrane electric potential difference, generated upon the energisation of the particles, should result in re-distribution of the semi-quinone Q anion (-Q-) across membrane, thus altering the equilibrium redox-state of respiratory carriers, interacting with redox-couples -Q/Q and QH2/-Q- in the mitochondrial membrane.