[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 xanthine oxidase in the cytotoxic action of nitrates and nitrites].

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.

[Nitric oxide synthesis in rats after BCG vaccination].

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.

[Role of xanthine oxidase and xanthine dehydrogenase systems in thymocyte apoptosis, induced by papaverine].

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.

[Effect of exogenous and endogenous nitrosation factors on formation of N-nitrosodimethylamine in rats depending on the status of purine catabolism].

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.

[Effect of some metabolites on the synthesis of nitric oxide by rat peritoneal macrophages].

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].

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.

[Use of chloroplasts for herbicide detection after thin layer chromatography].

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.

[N-demethylation and denitrosation activity of the rat liver, thymus lymphocytes and spleen after exposure to simazine and sodium nitrite].

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.

[The role of adenine nucleotide catabolism in the interphase death of thymocytes, caused by papaverine and dipyridamole].

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.

[Metabolism of adenosine, AMP and ATP in rats].

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.

[Metabolism of extracellular adenine nucleotides and adenosine uptake by rat thymocytes; the effect of concanavalin 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].

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.

[The creatine kinase system in rat thymus and thymocytes].

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.

[Characteristics of adenosine activity on adenine nucleotide metabolism of rat thymocytes].

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.

[Effect of papaverine on the absorption and metabolism of 14C- adenosine and 14C-adenine in thymocytes].

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.

[Effect of adenosine, AMP and papaverine on the cAMP content in thymocytes prelabelled with 14C-adenine].

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.

[Adenylate cyclase from rat thymus and spleen lymphocytes].

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.

[Creatine kinase of rat lymphocytes and its activity as affected by adenosine, cAMP, AMP and products of their transformation].

Creatine kinase is found in the thymus and spleen lymphocytes of rats. Its activity in the spleen lymphocytes is considerably higher than in the thymocytes. The data of enzyme-electrophoresis chromatography on DEAE-Sephadex A-50, thermostability and pH optimum indicate that lymphocyte creatine kinase is a "cerebral" isoenzyme.

[Application of sucrose density gradient in disk electrophoresis of proteins].

The methods are suggested when either fluid with the sucrose density gradient or the combination of sucrose with polyacrylamide gel are used as a zonal carrier in disk electrophoresis. Possibility is shown and conditions are selected for concentration and subsequent separation of proteins in the fluid with the sucrose density gradient in disk electrophoresis as narrow zones with clear boundaries. By the methods proposed the sarcoplasmic proteins of the rat myocardium and incorporated creatine kinase isoenzymes were separated.

[Determination of creatine kinase isoenzymes in rat tissues].

A method is developed for detection and quantitative determination of the creatine kinase isoenzymes during electrophoresis in agar gel. They are found in the agar gel block by formation of fluorescent sites due to combination of the isoenzymes reaction product: creatine with ninhydride in the alkaline medium followed by fluorophore quantitative elution. The method is specific, simple, highly sensitive.

[Properties of adenylate cyclase of rabbit skeletal muscle sarcolemma].

The sarcolemma fraction with a considerable adenylate cyclase activity sensitive to adrenalin is isolated from the rabbit skeletal muscles. Some its properties are established: pH-optimum of the activity, stability in storage and resistance to the effect of different pH and temperature. Acetylcholine and ruthenium red do not affect the adenylate cyclase activity of the sarcolemma.