[Interaction of eukaryotic aminoacyl-tRNA-synthases with polyribosomes]. / Izuchenie vzaimodeistviia éukarioticheskikh aminoatsil-tRNK-sintetaz s poliribosomami.

Properties of rabbit liver tissue aminoacyl-tRNA synthetases, associated with polyribosomes, were studied under conditions of normal state and within 12 hrs after simulation of myocardium infarction. Under conditions of myocardium infarction the activity of some forms of aminoacyl-tRNA synthetase was decreased in polyribosomes and protein fractions, liberated from polyribosomes by means of washing with buffer containing 0.5 M KCl. Polyribosomes stimulated the synthetases and protected them from heat inactivation. Deterioration of the synthetases interaction with polyribosomes appears to be among the factors responsible for impairment of protein biosynthesis under conditions of myocardium infarction.

[The role of long-chain acyl-CoA in the disturbances of oxidative phosphorylation in the myocardium]. / Rol' dlinnotsepochechnykh atsil-KoA v narushenii okislitel'nogo fosforilirovaniia v miokarde.

The effect of intramitochondrial acyl-CoA on the respiration of rabbit heart mitochondria in different metabolic states was studied. Acyl-CoA inhibited O2 consumption by 11% in State 4 and by 6% in State 3. However, the effect of acyl-CoA was more pronounced (20%) in the intermediate state of respiration between State 4 and State 3. The data obtained suggest that acyl-CoA can regulate oxidative phosphorylation in heart mitochondria in vivo.

[Study of the properties of leucyl-tRNA synthetase from porcine myocardium in a normal state and in experimental ischemia]. / Izuchenie svoistv leitsil-tRNK-sintetazy iz miokarda svin'i v norme i pri éksperimentalnoi ishemii.

Catalytic properties and thermostability of leucyl-tRNA-synthetase were studied both in free form and in the form of high molecular complexes, isolated from pig myocardium under normal state and after 15 min and 30 min ischemia. Km values of free and associated forms of leucyl-tRNA-synthetase were similar either in normal state or after 15-30 min ischemia. Complex-formation protected the enzyme from thermic inactivation under normal and ischemic conditions. Reverse redistribution of the leucyl-tRNA-synthetase activity was found in the fractions of free enzyme and high molecular complex depending on duration of ischemia.

[Distribution of aminoacyl-t-RNA-synthetase activity in rabbit liver cells during disruption of protein biosynthesis in experimental myocardia infarct]. / Raspredelenie aminoatsil-t-RNK-sintetaznoì aktivnosti v kletkakh pecheni krolikov pri narushenii biosinteza belka v usloviiakh éksperimental'nogo infarkta miokarda.

Distribution of the aminoacyl-tRNA synthetase activity has been studied in the normal rabbit liver cells and in the model of protein synthesis damage, i.e. under experimental myocardial infarction (EMI). The activity of a number of aminoacyl-tRNA synthetases in postmitochondrial and postribosomal extracts from rabbit liver homogenate has been determined to increase 12 h after EMI. Gel filtration of the postribosomal extract on Sepharose 6B shows that the activity of aminoacyl-tRNA synthetases is distributed among the fractions with Mr 1.82 x 10(6), 0.84 x 10(6) and 0.12 = 0.35 x 10(6). The first two fractions (high-molecular-weight aminoacyl-tRNA synthetase complexes) contain arginyl-, glutamyl-, isoleucyl-, leucyl-, lysyl- and valyl-tRNA synthetases, whereas the low-molecular-weight fraction contains alanyl-, arginyl-, glycyl-, phenylalanyl-, seryl-, threonyl-, tryptophanyl- and tyrosyl-tRNA synthetases. In a case of EMI all the aminoacyl-tRNA synthetases translocate from the complexes with Mr 1.82 x 10(6) into the complexes with Mr 0.84 x 10(6), what provided evidence for the possibility to regulate protein synthesis by changes in compartmentalization of aminoacyl-tRNA synthetases.

[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.

[The state of membrane structures of heart cells during ischemia]. / Izuchenie tselostnosti membrannykh struktur kletok serdtsa pri ishemii.

Under conditions of perfusion of isolated rabbit heart in aerobic medium and, especially, during ischemia, cytochrome c was liberated from heart cells into perfusate, thus indicating that integrity of mitochondrial outer membrane and of cell membrane was impaired. In situ developed deficiency of cytochrome c was distinctly less as compared with isolated mitochondria (50%, 3 hrs perfusion in ischemia), which appears to occur in response to ultrastructural impairments of mitochondria arising during their isolation and to other reasons.

[Participation of the adenine nucleotide translocator in the regulation of pyruvate oxidation in heart mitochondria]. / Uchastie perenoschika adeninnukleotidov v reguliatsii okisleniia piruvata v mitokhondriiakh serdtsa.

A regulatory role of adenine nucleotide translocator (ANT) was determined by titration of mitochondrial respiration (state 3) with carboxyatractyloside. It was shown that ANT regulates pyruvate oxidation: the control strength is more pronounced after depletion of endogenous substrates or after the increase in extramitochondrial ATP/ADP. The rate of succinate oxidation is controlled mainly by succinate dehydrogenase, while ANT does not participate in its regulation.

[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.

[Biological activity of tRNA and aminoacyl-tRNA-synthetases from the swine myocardium in anoxia and subsequent reoxygenation]. / Biologicheskaia aktivnost' tRNK i aminoatsil-tRNK-sintetaz miokarda svin'i pri anoksii i posleduiushchei reoksigenatsii.

Distinct decrease in the rate of aminoacylation of tRNAs, specific to alanine, glutamic acid, leucine and serine, was found after 20 min anoxia of perfused pig heart. In the anoxia activity of aminoacyl-tRNA synthetases of the same amino acid specificity was increased. Reduction of these macromolecules activity was observed in reoxygenation of the anoxic myocardium. Biological activity of tRNA and aminoacyl-tRNA synthetases in pig myocardium appears to depend on the supply of heart with oxygen.

[Dynamics of the accumulation of nonesterified fatty acids in the rabbit myocardium in total ischemia]. / Dinamika nakopleniia neéterifitsirovannykh zhirnykh kislot v miokarde krolika pri total'noi ishemii.

Isolated rabbit hearts were perfused within 30 min under conditions of adequate oxygenation in presence and absence (control perfusion) of monoiodacetate prior to total ischemia. Content of nonesterified fatty acids (NEFA) in rabbit hearts was determined under conditions of adequate oxygenation and total ischemia. The total NEFA content in control myocardium was 174 +/- 25 nanomoles per gram of wet weight. Ischemia within 30 min significantly enhanced concentration of NEFA, especially of stearic and arachidonic acids. Prolongation up to 120 min of ischemia caused nonspecific progressive increase in content of NEFA in myocardium. Monoiodacetate increased the concentration of NEFA both in ischemic and in oxygenated myocardium.

[The role of adenylate kinase in the regulation of the rate and effectiveness of energy transfer from mitochondria to hexokinase in vitro]. / Issledovanie roli adenilatkinazy v reguliatsii skorosti i éffektivnosti peredachi énergii ot mitokhondrii k geksokinaze in vitro.

The effect of adenylate kinase activity on the rate and efficiency of energy transport from mitochondria to hexokinase was studied in a system containing isolated rabbit heart mitochondria, hexokinase and adenylate kinase at low concentrations of adenine nucleotides. Oxygen consumption by mitochondria and glucose-6-phosphate synthesis by hexokinase were recorded. It was found that with adenylate kinase being active both in mitochondria and in the washing solution, the rate and efficiency of glucose-6-phosphate synthesis considerably increases. The effects of adenylate kinase activity are fully abolished by diadenosine pentaphosphate, an inhibitor of adenylate kinase. The experimental results based on the use of adenylate kinase demonstrate the possibility of increasing the rate and efficiency of energy transfer between two spatially uncoupled biochemical processes in vitro with the aid of an enzymatic system.

[Oxidation of fatty acids in heart mitochondria of the ischemic myocardium]. / Okislenie zhirnykh kislot v mitokhondriiakh serdtsa, podverzhennogo ishemii.

Oxidation of acetate, palmitoyl carnitine and palmitoyl-CoA was studied in isolated rabbit heart mitochondria. The highest rate of respiration was found if acetate was used as a substrate, the other substances studied were less effective. Oxidation of these substrates was gradually decreased after permanent coronary artery occlusion within 1, 4 and 24 hrs; the extent of the oxidation decrease was similar for all the substrates used. Incomplete oxidation of palmitoyl carnitine was observed in mitochondria from ischemic heart. Consumption of acetate in the mitochondria of control and ischemic animals exceeded distinctly its production in total respiration and in beta-oxidation of palmitoyl carnitine. The data obtained suggest that the decrease in coupled respiration, observed in mitochondria under conditions of ischemia, caused rather by lowering in respiratory capacity than by impairment of adenine nucleotides transport.

[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.

[Aminoacyl-tRNA synthetases and their high molecular weight complexes in autolysis of the swine heart]. / Aminoatsil-tRNK-sintetazy i ikh vysokomolekuliarnye kompleksy pri autolize serdtsa svin'i.

In pig myocardial extracts autolyzed within 15 min alanyl-, glycyl-, glutamyl-, leucyl- and seryl-tRNA synthetase activities were increased as compared with controls. The enzymatic activities were decreased after autolysis for 30 min. The 15 min autolysis was shown to decrease the molecular mass of the glycyl-tRNA synthetase complex. Within both 15 min and 30 min autolysis inorganic pyrophosphatase was markedly activated either in myocardium extracts or in high molecular complexes; this phenomenon may be responsible for activation of a number of aminoacyl-tRNA synthetases.

[Reasons for disorders of fatty acid oxidation in isolated heart mitochondria during ischemia]. / O prichinakh narusheniia okisleniia zhirnykh kislot v izolirovannykh mitokhondriiakh serdtsa pri ishemii.

The influence of malate and cytochrome c on fatty acid oxidation under control and ischemic conditions was investigated. In the medium without malate, cytochrome did not make fatty acid oxidation decreased during ischemia return to normal. Oxidation in the media containing malate and cytochrome did not differ from control only when it was measured after preliminary oxidation of endogenous substrates. The ratio of palmitoyl-CoA and palmitoyl carnitine to the respiration rates at state 3 was unchanged at 60 min ischemia. Apparently, no changes in carnitine acyltransferase playing a role in oxidation of palmitoyl-CoA took place. Thus, the decrease of fatty acid oxidation at early periods of ischemia is largely caused by a reduction in the content of cytochrome c and intermediates of Krebs cycle in the mitochondria.

[Lipid metabolism of the heart in ischemia and postischemic reperfusion]. / Lipidnyi obmen serdtsa pri ishemii i postishemicheskoi reperfuzii.

Content of unesterified fatty acids (FFA), phospholipids and triglycerides was studied in myocardium of control rabbits, of rabbits with ischemia (1 hr and 4 hrs) of myocardium and in postischemic reperfusion. In the ischemic myocardium content of phospholipids was gradually decreased; FFA increased within the first hour of ischemia. In reperfusion and prolongation of ischemia up to 4 hrs FFA were not altered. The data obtained suggest that a decrease in the ratio between the rates of FFA consumption and of lipid hydrolysis was responsible for an increase in the FFA content and in the phospholipid concentration.

[Fatty acid composition of mitochondrial phospholipids of the ischemic heart]. / Zhirnokislotnyi sostav fosfolipidov mitokhondrii ishemizirovannogo serdtsa.

Gas liquid chromatography was used to study fatty acid (FA) composition of lysophosphatidylcholine (lyso-PC) and phosphatidylcholine in isolated rabbit heart mitochondria. In control, lyso-PC and PC were found to contain 95 and 66% of unsaturated FA, respectively. At 1 hour of ischemia (autolysis at 37 degrees C) the percentage of saturated FA in lyso-PC noticeably increased whereas FA composition remained unchanged. It is concluded that changes in FA composition of lyso-PC are caused by phospholipase A2 action.

[Protein-synthesizing function of the liver of rabbits in experimental myocardial infarct]. / Beloksinteziruiushchaia funktsiia pecheni krolikov pri éksperimental'nom infarkte miokarda.

The content of serum albumin in rabbit blood was found to be lowered within the first day after reproduction of experimental myocardial infarction. The rate and the level of translation of endogenous mRNA were studied in cell-free systems from normal rabbit liver and 6-12-24 h after experimental myocardial infarction. The decrease of the total protein synthesis in the crude cell-free system from the liver of experimental animals was shown to depend on the lack of energy supply rather than on the reduced activity of the protein-synthesizing apparatus. The relative drop of protein synthesis in the cell-free system with saturating concentration of ATP, GTP and creatine phosphate is likely to be connected with a decrease in the proportion of membrane-bound polysomes.

[Kinetic differences in the oxidative phosphorylation system of control and ischemia-damaged heart mitochondria]. / O kineticheskikh razlichiiakh sistemy okislitel'nogo fosforilirovaniia kontrol'nykh i povrezhdennykh ishemiei mitokhondrii serdtsa.

Rabbit heart mitochondria isolated with or without rotenone (M + R and M -R, respectively) were studied. It was shown with the use of pHmetry that the Vmax of oxidative phosphorylation decreased during ischemia (autolysis for 0.5 h at 37 degrees C) in both preparations of the mitochondria to the same extent. The Km for ADP was unchanged in M - R, but rose significantly in M + R. Carnitine reduced the ischemia -increased Km value. The data suggest the inhibition of adenine nucleotide translocase by longchain acyl-Co A, whose level was found to be elevated by 52% in M + R during ischemia.

[Estimation of intact outer and inner membranes of heart mitochondria]. / Opredelenie intaktnosti naruzhnoi i vnutrennei membran mitokhondriiserdtsa.

A simple procedure is developed for estimation of the damage rate of inner membrane of heart mitochondria. In the assay the rate of succinate oxidation was measured using bromthymol blue as an inhibitor of succinate transport. Bromthymol blue at low concentration (12 microM) functioned as a mixed type inhibitor of succinate oxidation, whereas at high concentrations--as uncompetitive inhibitor. Polarographic registration of cytochrome c content and of the rate of ascorbate oxidation in the samples containing Triton X-100 and free of the detergent was more sensitive procedure as compared with spectrophotometric measurement of reduced cytochrome c oxidation in estimation of the damage rate of outer mitochondrial membranes. The damage rates of outer and inner membranes of heart mitochondria isolated by a procedure which included the treatment with trypsin were equal to 8.43 +/- 0.74% and 8.04 +/- 1.9%, respectively, while in those isolated without the trypsin treatment--12.8 +/- 1.5% and 13.3 +/- 1.8%, respectively.