[Role of interaction of metabolism pathways of formaldehyde and nitric oxide in the mechanism of their toxic effect. 3. Main metabolism sites of formaldehyde and nitric oxide mediating their effect].

Data are presented concerning the basic metabolism sites, the reaction paths crossing in them and regulatory and toxical effect of formaldehyde and nitric oxide being mediated through them. In particular, they include: glutathione-formaldehyde-dependent dehydrogenase path of S-nitrosoglutathione reduction, semi-carbaside-sensitive amino-oxidase (SSAO) and NO-synthase systems; transformation of thioproline and metallothioneines, including nitrosation reactions. Possibilities of hexamethylenetetramine synthesis in the organism as well as its metabolism in conditions of formaldehyde hyperproduction and nitrosative stress are discussed. The role of metabolism sites, common for formaldehyde and nitrogen oxide, in the mechanisms of toxical effect of these compounds and development of pathologic states is considered.

[The role of xanthine oxidase in the cytotoxic action of nitrates and nitrites]. / O roli ksantinoksidazy v tsitotokicheskom deistvii nitratov i nitritov.

It is established, that in rat organism nitrites and nitrates can be restored in nitrogen oxide due to nitrate and nitrite reductase activity of xanthine oxidase system. The rat thymocytes were shown in the experiment in vitro to have nitrate reductase activity, which was activated by hypoxanthine and inhibited by allopurinol. As a result of thymocytes apoptosis, provoked by papaverine, there is an essential increase of nitrate reductase activity of xanthine oxidase. The comparative research of thymocytes destruction character under the action of sodium nitroprusside (NP), N-nitrosodimethylamine (NDMA), NaNO2 and NaNO3 has been revealed, that their cytotoxicity, is dose-dependent and it decreases in order of these compounds mentioning. Synergism is revealed at the action on thymocytes of NP combined with sodium nitrite. These data as the results of investigation of EPR-spectrometry as well as use of thymocytes, containing a trap--complex of diethyldithiocarbamate-iron (DETK-Fe), allow to assume, that cytotoxic effect of NP is caused by the action of liberated from it. Cytotoxic action of nitrate is connected with reducibility to nitrite which influences on the cells independently, and nitrite action doesn't depend on its transformation to NO. The death of thymocytes caused by N-nitrosodimethylamine is not a result of its denitrozation.

[Nitric oxide synthesis in rats after BCG vaccination]. / Sintez oksida azota u krys pri in'ektsii vaktsiny BTsZh.

EPR research with use a trap NO--complex DTC-Fe has shown that NO synthesis increased 6 hours after vaccination and was maximal 10 days. The level of NO has decreased up to the initial significance 20 days after vaccination. Dynamics of EPR signals magnitudes in liver and blood for this period was investigated. We offer use BCG vaccination as a model for study of different factors and chemical substances effects on NO synthesis.

[Effect of exogenous and endogenous nitrosation factors on formation of N-nitrosodimethylamine in rats depending on the status of purine catabolism]. / Izuchenie vliianiia ékzogennykh i éndogennykh nitroziruiushchikh faktorov na obrazovanie N-nitrozodimetilamina u krys v zavisimosti ot sostoianiia purinovogo katabolizma.

Nitrogen dioxide's rats' inhalations with injections per os of pyrazole, amidopyrine and sodium nitrite lead to considerable increasing of endogenic N-nitrosodimethylamine formation, which had been determined by system gas chromatograph-thermal energetic analyser. This increasing essentially didn't depend on the rats' immunisation by vaccine BCG, which leads to the intensification of NO synthesis by peritoneal macrophages and others manifestations of their metabolic activation: increasing of creatine kinase and adenosine desaminase activities. It hadn't been brought to light the obvious dependent between changes of xanthine oxidase and xanthine dehydrogenase activities in the liver and blood serum and intensification of lipids peroxidation and also the amount of N-nitrosodimethylamine in the rats in the conditions of endogenic and exogenic nitrosation factors' influence.

[Role of xanthine oxidase and xanthine dehydrogenase systems in thymocyte apoptosis, induced by papaverine]. / Rol' ksantinoksidaznoi i ksantindegidrogenaznoi sistem v apoptoze timotsitov, indutsirovannom papaverinom.

It has been established that papaverine as well as other xenobiotics (dexamethasone and nitrosodimethylamine) [figure: see text] provoked the thymocyte death like apoptosis. The increase of the quantity of double-strand, single-strand DNA breaks and low molecular weight fragments of DNA preceded cell death. In papaverine-induced process of thymocyte apoptosis the total activity of xanthine oxidase in thymocytes strongly elevated long before their death, the conversion of xanthine dehydrogenase (D-form) to xanthinoxidase (O-form) and accumulation of O-form in the cultural medium took place. Direct stimulating effect of papaverine on O-form of enzyme in thymocyte lysate was revealed. The used digitonin thymocytes were divided into cytoplasmic and structural component fractions. It was shown that about 80% of total xanthinoxidase activity was concentrated in cytoplasma while only 20% of its activity was found in structural components. More higher ratio of xanthinoxidase/xanthindehydrogenase (XO/XDH) was observed and papaverine-induced changes of these enzyme forms activities were expressed more brightly in the structural components, than in the thymocyte cytoplasma. During the process of developing thymocytes apoptosis caused by papaverine the reaction of lipid peroxidation was intensified. XO-hypoxanthin system displaying prooxidant influence on cells increased the cytotoxic effect of papaverine but the presence of allopurinol or catalase and superoxidedismutase decreased it. Besides, cytotoxic action on thymocytes of allopurinol itself as well as hypoxanthin itself was revealed.

[Effect of some metabolites on the synthesis of nitric oxide by rat peritoneal macrophages]. / Izuchenie vliianiia nekotorykh metabolitov na sintez oksidov azota peritoneal'nymi makrofagami krys.

The peculiarities of some purine and energetic metabolites effect on the nitric oxide synthesis by vaccine BCG activated rat peritoneal macrophages has been studied. It was shown, that the glutamine and hypoxanthine caused essential increased of the nitrite level in the cell culture medium, but glutamic acid, adenosine, inosine and ATP did change these parameter. The mechanisms of studied compounds effect on the macrophages Ca(2+)-independent inducible NO-synthase activity are being discussed.

[Determination of DNA damage in nonproliferating animal cells]. / Opredelenie povrezhdenii DNK v neproliferiruiushchikh kletkakh zhivotnykh.

The modification of precipitation method for detecting DNA damage in mammalian cells using fluorimetric assay with 3.5-diaminobenzoic acid has been suggested. This modification allows determining DNA single- and double-strand breaks in mammalian nonproliferating cells and tissues. The influence of ionizing radiation upon the DNA damage in lymphoid cells of rat's spleen and thymus has been studied.

[Use of chloroplasts for herbicide detection after thin layer chromatography]. / Ispol'zovanie khloroplastov dlia detektirovaniia gerbitstidov posle khromatografii v tonkom sloe.

The procedure of spreading of native pea (Pisum sativum L.) chloroplasts and 2,4-dichlorophenolindophenol on thin-layer chromatographical plates is used to detect herbicides. The sensitivity of photosystem 2 inhibitors detecting ureas and simm-triazines, is 10 ng. Dinitroaniline, thiocarbamate and chloroacetamide herbicides may be detected on 100 ng level. The method may by used for the screening of new physiologically active compounds for phototoxicity.

[N-demethylation and denitrosation activity of the rat liver, thymus lymphocytes and spleen after exposure to simazine and sodium nitrite]. / N-demetiliruiushchaia i denitroziruiushchaia aktivnost' pecheni, limfotsitov timusa i selezenki krys pri vozdeistvii simazina i nitrita natriia.

Simazine and NaNO2 have been studied for their effect on cytochrome P-450-binding N-demethylation and denitrosation activity in the rat liver and lymphocytes in the subchronic (two-month-long) experiment. N-demethylation in lymphocytes of the thymus and spleen was higher than in the liver; denitrosation in the lymphocytes was not observed. Effects of simazine and NaNO2 being injected separately in most of cases have different directions. Combined injection of these substances exceeded the total effect.

[The role of adenine nucleotide catabolism in the interphase death of thymocytes, caused by papaverine and dipyridamole]. / Rol' katabolizma adeninnukleotidov v interfaznoi gibeli timotsitov, vyzvannoi papaverinom i dipiridamolom.

Papaverine and dipyridamole induce the interphase death of thymocytes rapidly growing four hours later and reaching its maximum by the seventh-eighth hour of the cell incubation. To induce death of thymocytes no constant presence of these preparations in the incubation medium is needed, a definite (for each of preparations) time of the contact with cells being enough. The interphase death of thymocytes induced by papaverine and dipyridamole is preceded by acceleration of the release of adenine nucleotide catabolism products from cells mainly as hypoxanthine and inosine, respectively. These both processes are induced by papaverine for a shorter period of its incubation with cells than by dipyridamole and the joined use of these substances intensifies the above processes. The analysis of the data obtained indicates that thymocytes under the effect of papaverine die rather from the exhaustion of the adenine nucleotide pool, than from a decrease in the adenylate charge of cells. Exogenous adenosine essentially removes the toxic effect of papaverine but not of dipyridamole. Addition of adenine and inosine to thymocytes does not affect their survival rate in the presence of the preparations under study.

[Metabolism of adenosine, AMP and ATP in rats]. / Metabolizm adenozina, AMP i ATP u krys.

Metabolism of [14C]adenosine in a dose of 100 mg per 1 kg of mass and [14C]ATP in the equimolar quantity was studied in rats after intraperitoneal administration. Adenosine is shown to enter tissues of the liver, spleen, thymus, heart and erythrocytes where it phosphorylates into adenine nucleotides (mainly ATP) and deaminates into inosine. The content of adenosine increases for a short period in the above tissues, except for erythrocytes and plasma. The latter accumulates a considerable amount of inosine and hypoxanthine, but only traces of uric acid, xanthine and adenine nucleotides. ATP administered to rats catabolizes through the adenosine formation. The exogenic adenosine and ATP replace in tissues and erythrocytes only a slight part (1-12%) of their total adenine nucleotide pool. The content of these metabolites and ADP in the blood plasma does not change essentially under the effect of adenosine, ATP and AMP. It is shown on rats whose adenine nucleotide pool of cells is marked by the previous administration of [14C]adenine that injections of adenosine, ATP and inosine do not accelerate catabolism of adenine nucleotides in tissues and erythrocytes as well as do not increase the level of catabolism products in the blood plasma. Adenosine enhances and ATP lowers the content of cAMP in spleen and myocardium, respectively.

[Metabolism of extracellular adenine nucleotides and adenosine uptake by rat thymocytes; the effect of concanavalin A]. / Metabolizm vnekletochnykh adeninnukleotidov i pogloshchenie adenozina timotsitami krysy; vliianie konkanavalina A.

Thymocytes under cultivation conditions are established to catabolyze rapidly extracellular ATP and AMP which do not penetrate through the plasma membrane. Thymocytes uptake adenosine produced from adenosine nucleotides. Concanavalin A inhibits the extracellular hydrolysis of AMP and adenosine uptake by thymocytes.

[Effect of dipyridamole and papaverine on adenosine absorption by the lymphocytes]. / Vliianie dipiridamola i papaverina na pogloshchenie adenozina limfotsitami.

It was shown that dipyridamole and papaverine induce concentration-dependent inhibition of the absorption of [14C] adenosine by thymocytes. This action is different in lymphocytes from different lymphoid organs and blood. Dipyridamole enhances the effect of various papaverine concentrations on the absorption of adenosine by thymocytes, but it does not exceed the maximal effect, achieved by the latter in high doses. It is supposed, that dipyridamole inhibits the cell transport of adenosine and papaverine influences the adenine-nucleotide metabolism.

[The creatine kinase system in rat thymus and thymocytes]. / Issledovanie kreatinkinaznoi sistemy timusa i timotsitov krysy.

The content of creatine phosphate, creatine and creatine kinase activity in thymus is shown to be 17.6, 5 and 4 times respectively higher, than in thymocytes isolated from this organ, both the level of adenine nucleotides and adenylate energy charge being practically the same. The creatine phosphate content in thymocytes decreases with addition of papaverine and remains unchanged under the influence of adenosine and concanavalin A. The creatine kinase activity increases considerably during the concanavalin A-induced thymocyte blasttransformation reaction. Creatine inhibits blasttransformation of thymocytes stimulated by this mitogen.

[Characteristics of adenosine activity on adenine nucleotide metabolism of rat thymocytes]. / Osobennost' deistviia adenozina na adeninnukleotidnyi metabolizm timotsitov krysy.

The effects of adenosine on adenine nucleotide metabolism in [14C]adenine-labeled rat thymocytes were studied. It was shown that adenosine increases the intracellular pool of adenine nucleotides, predominantly ATP, which is accompanied by marked acceleration of their catabolism and a release of labeled products (especially inosine, hypoxanthine and adenosine) from the thymocytes. The effect of adenosine depends on its concentration and manifests itself already at 10(-6) M. 2-Deoxycoformycin partly relieves the effect of adenosine on adenine nucleotide metabolism. Exogenous deoxyadenosine, inosine, hypoxanthine and adenine, unlike adenosine, do not significantly affect the adenine nucleotide catabolism and the label release from the cells. All the effectors under study strongly increase inosine transport from the thymocytes, and inhibit, with the exception of adenosine, the hypoxanthine release from the cells.

[Effect of adenosine, AMP and papaverine on the cAMP content in thymocytes prelabelled with 14C-adenine]. / Vliianie adenozina, AMF i papaverina na soderzhanie tsAMF v timotsitakh, predvaritel'no mechennykh 14C-adeninom.

A study was made of the effects of adenosine, AMP and papaverine on the content and specific radioactivity of cAMP and ATP in rat thymocytes prelabeled with 14C-adenine. It was established that each of the substances under study increases approximately 2-fold the intracellular cAMP content. Adenosine or AMP combined with papaverine raises the cAMP level more powerfully than it might be expected as a result of such an ordinary summation. Being cAMP precursors adenosine or AMP increase its level in thymocytes. However in the presence of papaverine they exercise their action via adenylate cyclase. Thymocytes demonstrate two ATP compartments prelabeled mainly with 14C-adenine relative to the general cellular ATP and are used for cAMP formation. The compartment with a greater specific radioactivity gives rise to cAMP in thymocytes incubated in the absence of effectors or upon addition of papaverine. The compartment having a lesser specific radioactivity serves as ATP source for adenosine or AMP-sensitive adenylate cyclase and rapidly catabolizes under the effect of papaverine.

[Effect of papaverine on the absorption and metabolism of 14C- adenosine and 14C-adenine in thymocytes]. / Vliianie papaverina na pogloshchenie i metabolizm [14C]adenozina i [14C]adenina v timotsitakh.

Some peculiarities of adenosine and adenine nucleotide metabolism in rat thymocytes were investigated. It was shown that the uptake of labelled adenosine or adenine by thymocytes is markedly inhibited by papaverine due to the decrease of the adenylate kinase activity, on the one hand, and to the acceleration of ATP catabolism and inosine and hypoxanthine release into the environment, on the other. ATP catabolism occurs in a special compartment which in [14C] adenosine and [14C] adenine prelabelled thymocytes has a higher specific radioactivity as compared with the whole cell. In [14C] adenine-prelabelled thymocytes and extracellular medium, papaverine does not influence the content but increases the specific radioactivity of adenosine.

[Adenylate cyclase from rat thymus and spleen lymphocytes]. / Izuchenie adenilattsiklazy limfotsitov timusa i selezenki krys.

It was found that adenylate cyclase from spleen lymphocytes is more active as compared to that from thymocytes, but is less sensitive to the activating effect of epinephrine and NaF. Adenylate cyclase from different subcellular fractions of thymocytes has different sensitivity to NaF. In the microsomal and mitochondrial fractions the enzyme is inhibited by NaF 7- and 2-fold, while in cell lysate and nuclear-cellular fractions it is activated 3- and 9-fold, respectively. In the presence of NaF adenosine, AMP, PPi and methylene diphosphonic acid inhibit the enzyme activity both in thymus and spleen lymphocytes. Creatine and CrP also significantly decrease the enzyme activity. NH4+ and concanavalin A have no effect and phytohemagglutinin stimulates the enzyme from both sources.