[Change in localization of cellular vesicular apparatus during differentiation of myoblasts into myotubules in cell culture].

The study of changes in the intracellular processes during differentiation of myoblasts into myotubules is of great importance for understanding several fundamental problems of cell biology. At first, this concerns the spatial organization of vacuolar apparatus that reflects the alterations in the properties of cell membranes, cytoskeleton elements and dynamics of vesicular transport in the course of differentiation. The distribution of acidic membrane organelles (lysosomes, late endosomes, Golgi cisternae) during the myotubule formation was revealed. It was shown that perinuclear localization of acidic organelles in myoblasts was replaced by diffuse distribution of these structures in the whole volume of myotubules. Using lipophilic fluorescent dyes, RH 414 and di-8-ANEPPS, the process of formation and dynamics of endocytic vesicles in myoblasts and myotubules was investigated. In the present work, semiconductive nanocrystals, quantum dots (QDs), conjugated with TAT-peptide, which belongs to cell-penetrating peptides, were used to characterize nonspecific endocytosis. It was shown that QDs--TAT complexes penetrate myoblasts but do not penetrate myotubules even after 24 h incubation, which might be connected with plasma membrane changes during the process of skeletal muscle differentiation.

[Untargeted quantum dots in confocal microscopy of living cells].

The problem of non-specific binding of quantum dots (QDs) with cells is very important but not fully understood taking into account the possible application of QDs in medical and fundamental studies. The interactions of untargeted CdSe/ZnS QDs with isolated frog muscle fibres, HeLa cells and J774 cells were investigated. The observations were performed on living cells using laser confocal microscopy (Leica TCS SL). The QDs covered with polyethylenglycol without any functional reactive groups with emission maximum at 565 nm were used in the study. This type of QDs is suggested to prevent an interaction of QDs with biological molecules. It has been shown that QDs do not enter HeLa cells, T-system and sarcoplasm of skeletal muscle fibres. However, during long-term incubation J774 cells can uptake QDs. The data obtained has demonstrated the diversity of interactions of untargeted QDs with different cell types and are important for understanding of the problems of non-selective uptake and cytotoxicity of QDs.

[AO distribution and fluorescence spectra in myoblasts and single muscle fibres].

Using spectral scanning regime of Leica TCS SL confocal microscope, acridine orange (AO) fluorescence spectra in nuclei and cytoplasms of living myoblasts L6J1 and frog single muscle fibres have been studied. AO fluorescence spectra in salt solutions dependent on free AO concentrations and in AO complexes with DNA have also been obtained for comparison. Myoblasts nuclei fluoresced in green spectral region with maximum at approximately 530 nm (corresponding AO monomers fluorescence), nucleoli fluoresced most brightly. Nuclear chromatin fluoresced not uniformly in these cells. We saw similar to myoblasts AO emission in nucleoli and nuclei of frog single muscle fibres. The uniformed weak green fluorescence was observed for myoblast cytoplasm. As to the muscle fibres sarcoplasm, we saw also AO green fluorescence in A-discs. In myoblasts and muscle fibre cytoplasm we saw the fluorescent red, yellow and green granules which were acidic organelles. The comparison of AO fluorescence spectra in living cells with fluorescence spectra of different AO concentrations and complexes of AO with DNA in buffer solutions allows estimation of AO concentration in acidic granules which is of interest in the investigation of cellular organelles functions in the processes of intracellular transport, adaptation, apoptosis and a number of pathological conditions.

[Confocal-microscopic study of skeletal muscle fibre membrane organelles during Zenker's (spreading) necrosis].

The changes of T-system and cellular acidic organelles during spreading (Zenker's) necrosis of frog skeletal muscle fibres have been investigated using laser confocal microscopy and several vital fluorescent dyes acridine orange, RH 414, DiOC6(3), rhodamine 123, fluorescein dextran. The formation of numerous vacuoles as a result of local T-system swelling is most characteristic for initial steps of Zenker's necrosis. Vacuoles can attain tens microns in length. They are located both near nuclear poles and between myofibres. Vacuoles maintain connections with the extracellular space up to the moment of contraction knot rejection, and under definite conditions (glycerol influx to fibre) vacuoles are reversible. They deform nuclei and sarcoplasmic reticulum cisternae. Cellular acidic organelles, accumulating acridine orange (lysosomes, late endosomes, Golgi apparatus cisternae) are situated in direct vicinity with normal and vacuolated T-system. The increase in acidic organelles number and size occur during the pathological process development, and tendency to vacuoles clusterization may be seen. Vacuolation of T-system during necrosis is not followed by vacuole content acidification. The role of cellular acidic organelles and of T-system vacuolation in the development of different muscle pathological changes is discussed.

[Effect of alkaloid sanguinarine and a pharmaceutical preparation ukrain on modulation of vesicular membrane fusion and actin cytoskeleton of macrophages].

A study was made of modulations of lysosome-phagosome fusion process and of fibrillar actin content in mouse peritoneal macrophages by an antitumor alkaloid sanguinarine and a derivative drug Ukrain. In addition, effects of these substances on in vitro polymerization of monomeric globular actin from rabbit muscle were investigated. Sanguinarine and Ukrain stimulated lysosome-phagosome fusion and increased the content of polymerized fibrillar form of actin in mouse macrophages. Effects of these substances were enhanced at their higher concentrations. Both sanguinarine and Ukrain induced in vitro polymerization of globular actin from rabbit muscle. A possible role of sanguinarine and Ukrain in changing vesicular membrane states during intracellular membrane interaction in lysosome-phagosome fusion process was discussed. The influence of these substances on actin polymerization and actin cytoskeleton rearrangement was evaluated. It could be supposed that sanguinarine and Ukrain may alter intracellular membrane transport.

[Localization of acid organelles in frog skeletal muscle fibers]. / Lokalizatsiia kislykh organoidov v skeletnykh myshechnykh voloknakh liagushki.

By means of fluorescent and phase-contrast microscopy the distribution of acid membrane organelles in normal and vacuolated frog skeletal muscle fibers has been studied. The vacuolation of the T-system was produced by loading and subsequent removal of glycerol (80-110 mM), or it appeared as a result of Zenker's necrosis. Acridine orange (AO) was used as a marker for acid intracellular compartments. AO accumulated in granules localized near the nuclear poles (more seldom around the nucleus)' and in the intermyofibrillar spaces. Typically the AO granules make up short longitudinal chains or regular pairs, where the distances between neighboring granules are short-dated to sarcomere lengths. Almost all granules emit in red, but about one third of them simultaneously emit in green, which is characteristic of AO monomers. In the vicinity of necrotic boundary or under the influence of brefeldin A, a green component of fluorescence appears in most granules. Treatment with monensin leads to granule disappearance. Vacuoles accompanying the glycerol treatment or developing of necrosis do not accumulate AO and exert no effect on the localization of AO-granules. The nature of cellular organelles accumulating AO in skeletal muscle fibers is discussed.

[Effects of cationic vectors complexed with plasmid DNA on the phagosome-lysosome fusion in murine peritoneal macrophages and J744 macrophages]. / Vliianie kationnykh vektorov transfektsii v komplekse s plazmidnoi DNK na sliianie lizosom s fagosomami v peritoneal'nykh makrofagakh myshi i v makrofagakh linii J774.

Polyethylenimine (PEI) and cationic polypeptides complexed with plasmid DNA are the most efficient nonviral vectors for gene therapy. It is believed that endocytosis is the major pathway for cell entering by PEI/DNA or cationic peptides/DNA complexes. Effects of plasmid DNA complexed with PEI, poly-L-lysine (PLL), poly-D-lysine (PDL) and polyarginine (PA) on the phagosome-lysosome fusion (P-LF) were studied in murine peritoneal macrophages and J774 macrophages. Cationic polypeptide PLL can be hydrolysed by cellular peptidases, but its stereoisomer, PDL, cannot be split by these enzymes. PEI, PDL, and PA have been shown to inhibit P-LF. PLL showed a low effect on the P-LF. On the basis of these studies, we assume that lysosomotropic agents able to change functions of lysosomes in the cell may affect transfection efficiency and thus be used for gene therapy.

[Effect of polyamine synthesis inhibitors separately and in combination with epidermal growth factor on fusion of lysosomes with phagosomes and F-actin level in mouse peritoneal macrophages]. / Vliianie ingibitorov sinteza poliaminov razdel'no i v sochetanii s épidermal'nym faktorom rosta na sliianie lizosom s fagosomami i na soderzhanie F-aktina v peritoneal'nykh makrofagakh myshi.

Effects of polyamine (PA) synthesis inhibitors--alpha-difluoromethylornithinchloride (DFMO) and alpha-methylornithinchloride (MO)--separately or in combination with the epidermal growth factor (EGF)--on lysosome-phagosome fusion (P-LF) and F-actin content in murine peritoneal macrophages were studied using fluorescent dye Acridine orange for lysosome labelling, FITC-phalloidin for F-actin, and yeast cells as a target. DFMO and MO significantly inhibited P-LF and decreased F-actin content in murine peritoneal macrophages. A combination of DFMO and MO with EGF failed to inhibit P-LF or to decrease F-actin content in these cells. The results obtained with DFMO and MO suggested new cellular targets of their effects. These results may be extended to cancer research to provide a rationale for clinical trials using combinations of EGF with DFMO or MO.

[Tartrate-sensitive and tartrate-resistant acid phosphatases in Amoeba proteus]. / Tartrat-chuvstvitel'naia i tartrat-rezistentnaia kislye fosfatazy u ameb Amoeba proteus.

In free-living Amoeba proteus (strain B), acid phosphatase (AcP) was examined by disc-electrophoresis in polyacrylamide gel. The tartrate-sensitive amebian AcP was greatly inhibited by dithiothreitol and Cu2+, and only partly inhibited by sodium orthovanadate, ammonium molybdate, EDTA, disodium salt and Mg2+, Ca2+, Zn2+ and Mn2+. On the contrary, it appeared to be resistant to sulfhydryl reagents--4(hydroxymercury) benzoic acid, sodium salt and N-ethylmaleimide. Unlike the tartrate-sensitive enzyme, the tartrate-resistant AcP was greatly inhibited by EDTA and partly inhibited by dithiothreitol, Mg2+ and Cu2+ (Mn2+ > Cu2+), being activated by orthovanadate, molybdate, sulfhydryl reagents, Mg2+, Ca2+ and Zn2+. Both tartrate-sensitive and tartrate-resistant AcPs lack apparently free SH-groups necessary for their catalytic activities. Using 2-naphthyl phosphate as a substrate at pH 4.5, six AcP electromorphs were revealed in cytosol and sediment, four of these being most frequently localized in the former, and two in the latter. Two other AcP electromorphs were confined to the sediment only. Depending on the quantity of sedimented amoebae making a homogenate (0.5 or 2.0 cm3), that was added to Percoll solution, the lysosomal AcP fraction in polyacrylamide gel was represented by one or two tartrate-sensitive electromorphs. Therefore, tartrate-resistant AcP in A. proteus may be a lysosomal enzyme, while tartrate-resistant AcP may correspond to serine/threonine protein phosphatase.

[Effect of some DNA-intercalators and antioxidants on the phagosome- lysosome fusion and F-actin content in murine peritoneal macrophages]. / Vliianie nekotorykh DNK-interkaliatorov a antioksidantov na sliianie fagosom s lizosomami i na soderzhanie F-aktina v peritoneal'nykh makrofagakh myshi.

Effect of DNA-intercalators ethidium bromide (EB, 0.005 and 0.015 mM) and dimidium bromide (DB, 0.005 and 0.010 mM) and antioxidative compounds acetylsalicylic acid (ASA, 0.05 and 0.50 mM) and beta-carotene (0.01, 0.02, 0.05 mM) on the phagosome-lysosome (P-L) fusion and F-actin content in murine peritoneal macrophages were studied. EB, DB, ASA and beta-carotene were found to stimulate P-L fusion and the effect depending on the concentration of compounds tested. The strongest influence as evoked by 0.5 mM of ASA and 0.05 mM of beta-carotene. The compounds tested enhanced the F-actin content in macrophages, especially by the action of beta-carotene (0.05 mM). The obtained data indicate a correlation between P-L fusion stimulation and F-actin content under the influence of compounds tested in murine peritoneal macropheages.

[Sanguinarine and ellipticine cytotoxic alkaloids isolated from well-known antitumor plants. Intracellular targets of their action]. / Sangvinarin i elliptitsin: tsitotoksicheskie alkaloidy, vydelennye iz izvestnykh protivoopukholevykh rastenil, i vnutrikletochnye misheni ikh delstviia.

Common molecular and cellular targets for alkaloids sanguinarine and ellipticine, isolated from well-known antitumor plants (as well as from their various natural and synthetic derivatives), have been studied and described. Sanguinarine and ellipticine are characterized by significant biological activities including a high antitumor potential. Among the important targets of their action the following are to be noted. 1. DNA and other double helical polynucleotides. Due to the ability of DNA-intercalation sanguinarine, ellipticine and some of their derivatives can modify the double helical structures and topological forms of polynucleotides. The results of these modifications in intercalative complexes manifest themselves in the inhibition of numerous enzymatic reactions, dependent on the structures and topological forms of DNA and other polynucleotides. 2. ATP synthesis in mitochondria. Most of DNA-intercalators, including sanguinarine and ellipticine, belong to a group of penetrating (hydrophobic) cations, which are accumulated near the external side of inner mitochondrial membranes during the membrane energization. They neutralize negative charges, arising just as the inner mitochondrial membranes become energized. By this neutralization of membrane charges the ATP synthesis in inhibited and the oxidative phosphorylation renders to be uncoupled. All studied DNA-intercalators under certain conditions uncouple the mitochondrial oxidative phosphorylation. Apparent correlation between the agents' ability for DNA-intercalation and for mitochondrial ATP synthesis inhibition seems to be determined by the importance for both types of reactions of molecule hydrophobicity and positive charges. 3. Cholinesterase systems. Sanguinarine, ellipticine and some of their derivatives, like other DNA-intercalators studied, inhibit also the enzymatic activities of cholinesterase systems due to hydrophobicity and positive charges of their molecules. 4. Sanguinarine (and chelerythrine), are also capable of inhibiting the biological activity of SH-dependent enzymes and proteins. Due to the reactivity of iminium groups in sanguinarine and chelerythrine molecules with nucleophilic reagents, e.g. thiol groups of enzymes and other proteins, the activities of SH-enzymes and proteins are inhibited. In particular, sanguinarine and chelerythrine inhibit enzymatic activity of some SH-dependent ATPases, including membrane-bound cation-transport ATPases. The earlier accumulated experience of the application in medicine of plant saps and extracts containing these alkaloids, and of the treatment of many diseases (including benign and malignant tumors) by isolated alkaloids may be explained, to a certain extent, by the inhibition of activities of the above mentioned cellular targets. The selective toxicity of these alkaloids for the number of transformed cells can be explained in the same manner.

[The effect of biologically active compounds on lysosome fusion with phagosomes and the F-actin content in mouse peritoneal macrophages and on the status of the lysosomal membranes in mouse hepatocytes]. / Vliianie biologicheski aktivnykh soedinenii na sliianie lizosom s fagosomami i soderzhanie F-aktina v peritoneal'nykh makrofagakh myshi i na sostoianie lizosomnykh membran gepatotsitov myshi.

Effects of biologically active compounds bilirubin (BR, 0.1 and 0.2 mM), chelerythrine (CR, 0.1 and 0.5 mM) and farmorubicin (FR, 0.6 and 6.0 mM) on the phagosome-lysosome fusion (P-LF) were studied using fluorescent dye acridine orange for lysosomal labelling and yeast cells as a target. To investigate mechanisms of these effects, changes in fluidity of lysosomal membranes from murine liver were studied by measuring of fluorescence intensity, lifetime and polarization of the fluorescent membrane probes: DPH (1,6-diphenyl-1,3,5-hexatriene) and TMA-DPH [1-(4-triphenylamino)-6-phenyl-1,3,5-hexatriene] incorporated in isolated murine liver lysosomes. In order to characterize the induced cytoskeleton changes, the F-actin content in murine peritoneal macrophages was determined. It was found that all three compounds tested enhanced P-LF. Our results demonstrate that BR induces a decrease in DPH and TMA-DPH fluorescence polarization, FR increases DPH and TMA-DPH fluorescence polarization, and CR causes an increase in TMA-DPH fluorescence polarization in lysosomal membranes. All the three compounds increase F-actin content in peritoneal macrophages. Thus, the action of BR extended on P-LF is associated with increasing lysosomal membranes fluidity and cytoskeleton changes. The enhancement of P-LF under the action of FR and CR can be most likely explained by changes of cytoskeleton.

[A disorder in the energy-conversion processes in the liver mitochondria of rats under the action of sanguinarin and AFMA]. / Narushenie protsessov prevrashcheniia énergii v nitokhoindriiakh pecheni krys pod deistviem sangvinarina i AFMA.

Processes of energy transduction were studied in isolated rat liver mitochondria, taken as a possible target for DNA intercalators, which differs from a usual one, associated with nucleic acid metabolism reactions. In the mitochondrial suspension, changes in respiration rates and latent ATPase activity in controlled state were defined in addition to a decrease in respiratory control index (V2/V1) and P/O ratio under the influence of DNA intercalators, benzophenanthridine alkaloid sanguinarine and acridine derivative APhMA. Within the range of examined sanguinarine and APhMA concentrations, the increase in respiration rate and activation of latent ATPase activity of mitochondrial suspension was first determined, with the maxima of these activities at 10(-4) M for both the agents. A further increase in sanguinarine and APhMA concentrations caused the inhibition of these reactions. Such dose-dependent shapes, with a maximum for the curves of mitochondrial respiration rate and ATPase activity "bell-shaped"), are typical for the majority of so far known uncouplers of oxidative phosphorylation in mitochondria. The fall of V2/V1 and P/O, under the influence of sanguinarine and APhMA, evidenced for the inhibition of ATP synthesis in mitochondria. The mechanism of uncoupling by sanguinarine and APhMA was supposed to differ from that by protonophores. It has been suggested that the uncoupling of oxidative phosphorylation by sanguinarine and APhMA was associated with the ability of these organic cations to neutralize negative charges near the external side of energized internal mitochondrial membranes. Correlation between the capacity for DNA intercalation and that for the energy transfer inhibition in mitochondria of these two agents is presumably based on the importance of positive charges and hydrophobic interactions, both for intercalation into polynucleotide double helices and for negative charges neutralization in energized mitochondrial membranes. Among DNA intercalators, so far examined, no agent has been established, which would not disturb the coupling of respiration and phosphorylation in mitochondria. However, there is no strong correlation for the agents between the ability to intercalate into DNA double helix and to disturb the energy transfer processes in mitochondria. Sanguinarine, which is more potent, as a DNA intercalator, than APhMA, is weaker than APhMA as an uncoupler of mitochondrial oxidative phosphorylation. For DNA-intercalation, the steric conformity between sizes of the intercalator molecule and of DNA base pairs is of great importance. On the other hand, for mitochondrial energy transfer disturbance, the agent ability to achieve sites of negative charges in the energized inner membranes is more significant.

[The protein spectrum and thermostability of the lysosomal hydrolases in heat-resistant sublines of Chinese hamster cells]. / Izuchenie spektra belkov i teploustoichivosti lizosomal'nykh gidrolaz v termorezistentnykh subliniiakh kletok kitaiskogo khomiachka.

It has been shown by electrophoresis that the earlier obtained thermoresistant sublines of the CHO-K1 cell line do not accumulate heat shock proteins when cultured at 37 degrees C. The thermostability of two lysosomal proteins--acid lipase and acid phosphatase--were higher in the thermoresistant cells than in the parental cells, whereas no differences in thermostability of galactosidase were found between heat resistant and parental lines. Thus, it is concluded that changes in the level of conformational flexibility of protein molecules may be one of the mechanisms of cell adaptation to growth at higher temperatures.

[DNA intercalators: their interaction with DNA and other cell components and their use in biological research]. / DNK-interkaliatory: vzaimodeistvie s DNK i drugimi kletochnymi komponentami i primenenie v biologicheskikh issledovaniiakh.

DNA intercalators include aromatic heterocyclic compounds of various chemical classes with profound biological activities. The flat molecules of these ligands intercalate between base pairs of DNA right-handed helix, lengthening and unwinding this structure at the intercalation sites. Lerman first postulated the intercalation model for complexes of native DNA with acridine derivatives. The structures of intercalative complexes were further confirmed by the X-ray diffraction method. Besides, other physico-chemical criteria of DNA intercalation are as following: the increase in the contour length of duplex DNA; unwinding of supercoils from natural supercoiled covalently closed duplex DNA; the increase in Tm of DNA in the complexes with ligands. The changes of spectral properties of bounded ligands are also observed for DNA-intercalating agents. Various experimental methods are based on changes in the properties of nucleic acid structures and ligands due to DNA intercalation, including the fluorescent determination of nucleic acid structures and quantities; fluorescent assays of activities of various enzymes involved in nucleic acid metabolism; chromosome identification according to their fluorescent banding patterns; separation of nucleic acid topological forms, and many other methods. The inhibition of reactions of DNA replication, transcription, topoisomerization and of enzymatic degradation by DNA intercalators represents an important consequence of DNA structure modification due to intercalation. Besides, as hydrophobic cations DNA intercalators uncouple the oxidative phosphorylation in mammalian cell mitochondria. There are some other protein and phospholipid targets for DNA-intercalators in vivo. The intracellular distribution of these agents appear to be a very complicated selective process. These data point to the importance of application of DNA intercalators in pharmacology.

[Effect of sanguiritrine on the functional activity of fibroblast lysosomes]. / Deistvie sangviritrina na funktsional'nogo aktivnost' lizosomnogo apparata fibroblastov.

Kinetics of sanguiritrine consumption by L cells of LSM substrain was studied in cell culture. About half of the drug used was absorbed by cells within 20 min. Sanguiritrine inhibited the lysosomal hydrolases (cathepsin D, beta-D-galactosidase and N-acetyl-beta-D-glucosaminidase) activity by 50% at concentration 2.10(-4) M. The drug a concentration 4.10(-4) M inhibited acid lipase by 55% and acid phosphatase by 58%.

[The toxicity of sanguinarine compared to a number of other DNA-tropic compounds for ethidium bromide-sensitive and -resistant transformed murine fibroblasts in culture]. / Toksichnost' sangvinarina v sravnenii s riadom drugikh DNK-tropnykh soedinenii dlia chuvstvitel'nykh i rezistentnykh k bromistomu étidiiu transformirovannykh myshinykh fibroblastov v kul'ture.

A natural DNA-intercalator plant benzo-c-phenanthridine alkaloid sanguinarine is more toxic for mouse transformed fibroblast L-cells in culture than synthetic DNA-intercalator ethidium bromide (EtB) and alkaloid berberine. Dimidium bromide is also an inhibitor of the L-cell growth. In assay conditions, growth of L-cells is stopped by 1.5 x 10(-5) M of sanguinarine. Lebr-625 cells, resistant to 25 micrograms/ml of EtB, have sanguinarine sensitivity close to that of L-cells, but Lebr-625 cells are resistant to dimidium bromide. Sanguinarine is more toxic for L-cells in culture than the anticancer drug cis-PtNH3)2Cl2. Trans-Pt(NH3)2Cl2 is less toxic for these cells. The strong toxicity of sanguinarine for L- and Lebr-625 cells in culture, as compared to other DNA-complexing drugs, seems to be associated with the wide range of potential cell targets for sanguinarine influence. Besides the inhibition of nucleic acid metabolism reactions, characteristic of DNA-intercalators, and disruption the mitochondrial ATP synthesis, also characteristic of organic heterocyclic cationic molecules of DNA-intercalators, sanguinarine can modify the thiol groups of enzymes including SH-sensitive membrane-bound Na+, K(+)-ATPase of cerebral cortex and Ca2(+)-ATPase of skeletal muscle sarcoplasmic reticulum fragments.

[Inhibition of the activity of membrane-bound Ca2+-ATPase in the sarcoplasmic reticulum fragments of rabbit skeletal muscles by the alkaloid sanguinarine]. / Ingibirovanie aktivnosti membranosviazyvannoi Ca2+-ATFazy fragmentov sarkoplazmaticheskogo retikuluma skeletnykh myshts krolika alkaloidom sangvinarinom.

Sanguinarine, a plant DNA-intercalator, is shown to inhibit the enzyme activity of the membrane-bound Ca2+-ATPase of rabbit skeletal muscle sarcoplasmic reticulum fragments. This inhibition could be interpreted by the well known ability of this alkaloid to interact with sulphydryl groups of the enzymes. Sanguinarine is a weaker inhibitor of this reaction than a sulphydryl group poison Ag+. The I50 is 3.10(-6) M for Ag+ and 7.10(-5) M for sanguinarine in the reaction medium with NO3- substituted for Cl-. In the standard reaction medium containing Cl-, the I50 for sanguinarine is 1.8.10(-4) M. In this case sanguinarine activates Ca2+-ATPase at low concentrations presumably because of uncoupling ATP hydrolysis from Ca2+ transport through membrane. Other agents studied are: DNA-intercalators--ethidium bromide, acriflavine, acridine orange; DNA-complexing antibiotics--actinomycin D, and olivomycin, alkaloids, quinine, morphine, berberine and an uncoupler of oxidative phosphorylation 2,4-dinitrophenol. These were found not to inhibit Ca2+-ATPase activity up to the concentrations of 10(-3)-10(-4) M.

[Effect of a number of biologically active substances on the activity of membrane-bound Na+,K+-ATPase from the bovine brain]. / Vliianie riada biologicheski aktivnykh veshchestv na aktivnost' membranosviazannoi Na+,K+-ATFazy mozga byka.

Cellular Na+, K+-transport ATPase appears to be more resistant to the influence of DNA intercalators and other agents than ATP-synthetase complex of inner mitochondrial membrane. Neither synthetic intercalators, nor antibiotics olivomycin and actinomycin D, some uncouplers of oxidative phosphorylation, alkaloids and inorganic bivalent cations selectively (up to 10(-4) M) inhibit Na+, K+-ATPase activity. Besides ouabain, alkaloid sanguinarine and cation Ag+ (the latter in the absence of anion Cl-) cause a significant decrease of Na+, K+-ATPase activity. Ag+ is most potent as inhibitor, while sanguinarine is weaker than ouabain. Inhibition of Na+, K+-ATPase by sanguinarine may result presumably from modification of SH-groups of the enzyme.