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PubMed1994

Nitric oxide production by activated human neutrophils exposed to sodium azide and hydroxylamine: the role of oxygen radicals.

The occurrence of a nitric oxide-generating system in human neutrophils has been controversial and the detection of nitric oxide rendered more difficult due to the capacity of oxygen radicals and other compounds to scavenge this molecule. Our results demonstrate that human neutrophils, when stimulated by adherence or by phorbol myristate acetate generate nitrite upon exposure to NaN3 or hydroxylamine. NaN3-dependent nitrite production was further increased by the addition of superoxide dismutase (SOD). The generation of nitrite was also stimulated by exogenous added H202 in resting neutrophils and could be induced in a cell-free system containing heme-enzymes, H202 and NaN3, suggesting a requirement for H202-mediated oxidation of NaN3 in nitrite formation by the stimulated cells. Treatment of the neutrophils with hydroxylamine led to the production of even larger quantities of nitrite (> 25 nmol/h.10(6) cells), an effect that was prevented by SOD, pointing to superoxide as a metabolite possibly involved in nitrite formation. These results emphasize the importance of oxygen radicals or other intermediates in the generation of nitrite by stimulated neutrophils exposed to the above compounds.

Azides↗
PubMed1991

Topology of the chloroperoxidase active site: regiospecificity of heme modification by phenylhydrazine and sodium azide.

Chloroperoxidase (CLP) from Caldariomyces fumago is rapidly and irreversibly inactivated by phenylhydrazine and H2O2 but not by H2O2 alone. Inactivation is characterized by a phenylhydrazine-to-CLP partition ratio of approximately 15, formation of trans-azobenzene, and formation of a sigma-bonded phenyl-iron heme complex with a characteristic absorption maximum of 472 nm. Anaerobic extraction of the heme complex from the protein, followed by exposure to dioxygen under acidic conditions, shifts the phenyl group from the iron to the porphyrin nitrogens and yields the four possible N-phenylprotoporphyrin IX regioisomers. Oxidation of the iron-phenyl complex within the intact protein by ferricyanide or high peroxide concentrations results in protein-directed phenyl migration to give exclusively the N-phenylprotoporphyrin IX regioisomers with the phenyl group on pyrrole rings A and C. CLP also catalyzes the H2O2-dependent oxidation of azide to the azidyl radical and is inactivated by azide in the presence of H2O2. Inactivation of CLP by azide and H2O2 results in loss of heme Soret absorbance and formation of delta-meso-azidoheme. These results suggest a topological model for the CLP active site and indicate that the tertiary structure of the enzyme permits substrates to interact with both the delta-meso heme edge and catalytic ferryl (FeIV = O) species, in agreement with the fact that CLP catalyzes both H2O2-dependent peroxidation and monooxygenation reactions.

Animals↗
PubMedDate not supplied

[The use of sodium azide as a fecal preservative for studying the eggs of Schistosoma mansoni and of other helminths by the Kato-Katz method: a study in an endemic area].

In two aliquots of 208 samples of stool, tests have been made by the Kato-Katz method, one being made after the use of 0.2mg of sodic azide for 200mg, and the other without the aforesaid conservant. The resulted percentages with or without the conservant were, respectively, for Ancylostomideos: 12.5 and 25.9; for Ascaris lumbricoides: 71.6 and 72.5; for Schistosoma mansoni: 7.6 and 17.7, and for Trichuris trichiura: 86 and 85. The count of the eggs with and without the conservant was, respectively, 264 and 539 for Ancylostomideos, 13186 and 33751 for A. lumbricoides, 55.5 and 63.5 for S. mansoni, and 1345 and 2068 for T. trichiura. The authors did not confirm the advantage of using sodic azide for study in endemic areas. They suggest that the exsiccation of the stool and the low intensity of infections can explain the unfavourable results of the present clinical trial.

Animals↗
PubMed1998

Sodium azide enhances neutrophil migration and exocytosis: involvement of nitric oxide, cyclic GMP and calcium.

Azide, in the absence of other stimuli, enhanced neutrophil migration in a chemotactic way. The effect of azide on migration was significant at concentrations > or = 1 microM and maximal at 10 microM azide. Although azide itself could not induce exocytosis, at concentrations > or = 10 microM azide enhanced exocytosis induced by a combination of the chemotactic peptide f-methionyl-leucyl-phenylalanine (fMLP) and cytochalasin B (CB). Azide can be oxidized by catalase and myeloperoxidase in the presence of H2O2, resulting in the generation of nitric oxide (NO). Formation of NO from azide was detected by ESR spectroscopy with carboxy-PTIO as a NO-selective probe, and by measurement of nitrite formation. Azide-induced migration, and the enhancement by azide of fMLP/CB-induced exocytosis, were blocked by pre-incubating cells with aminotriazole, an inhibitor of catalase and myeloperoxidase, suggesting that the effect of azide was mediated by NO. Azide-induced migration, but not the enhancement by azide of fMLP/CB-induced exocytosis, was inhibited to a large extent by inhibitors of soluble guanylate cyclase and by inhibitors of cGMP-dependent protein kinase. These observations suggest that azide-induced migration is mediated via cGMP and cGMP-dependent protein kinase, while the enhancement of fMLP/CB-induced exocytosis is not. Azide caused a sustained elevation of the intracellular Ca2+-concentration of neutrophils stimulated with fMLP/CB, which was not affected by inhibitors of the cGMP-signalling cascade. Since neutrophil exocytosis has been shown to be closely correlated with increases in intracellular Ca2+, a further increase by azide of the intracellular Ca2+-level of cells stimulated with fMLP/CB provides a likely mechanism for the enhancement of fMLP/CB-induced exocytosis by azide.

Animals↗
PubMed2004

[Organelle redistribution during PK cell spreading in normal conditions and in the presence of sodium azide].

Cell detachment from solid substratum results in a changed arrangement of cytoplasmic organelles and, primarily, in disruption of the centrosome and Golgi complex colocalization. In the course of cell spreading, reorganization of intracellular compartments occurs by stages. At first, mitochondria disperse in the cytoplasm volume, then the centrosome and Golgi complex unite, and finally collapse of intermediate filaments disappears. In the presence of Na azide the establishment of intracellular compartments during cell spreading proceeds in a similar manner. However, unlike the normal conditions, here atypical intracellular compartments appear: some of these containing lysosomes and lipid inclusions and located in the perinuclear area, and others with extended cisterns of endoplasmic reticulum on the cell periphery. Addiitionally, in the presence of Na azide the density of microtubules and intermediate filaments increases. It has been suggested that changes in the cytoskeleton organization lead to an enhanced cell spreading.

Animals↗
PubMed1976

Appearance of magnesium guanylate cyclase activity in rat liver with sodium azide activation.

Native soluble and particulate guanylate cyclase from several rat tissues preferred Mn2+ to Mg2+ as the sole cation cofactor. Wtih 4mM cation, activities with Mg2+ were less than 25% of the activities with Mn2+. The 1 mM NaN3 markedly increased the activity of soluble and particulate preparations from rat liver. Wtih NaN3 activation guanylate cyclase activities wite similar with Mn2+ and Mg2+. Co2+ was partially effective as a cofactor in the presence of NaN3, while Ca2+ was a poor cation with or without NaN3. Activities with Ba, Cu2+, or Zn2+ were not detectable without or with 1 mM NaN3. With soluble liver enzyme both manganese and magnesium activities were dependent upon excess Mn2+ or Mg2+ at a fixed MnGTP or MgGTP concentration of 0.4 mm; apparent Km values for excess Mn2+ and Mg2+ were 0.3 and 0.24 mM, respectively. After NaN3 activation, the activity was less dependent upon free Mn2+ and retained its dependence for free Mg2+, at 0.4 mM MgGTP the apparent Km for excess Mg2+ was 0.3 mM. The activity of soluble liver guanylate cyclase assayed with Mn2+ or Mg2+ was increased with Ca2+. After NaN3 activiation, Ca2+ had no effect or was somewhat inhibitory with either Mn2+. After NaN activation, Ca2+ had no effect or was somewhat inhibitory with either Mn2+ or Mg2+. The stimulatory effect of NaN2 on Mn2+-and Mg2+-dependent guanylate cyclase activity from liver or cerebral cortex supernatant fractions required the presence of the sodium azide-activator factor. With partially purified soluble liver guanylate cyclase and azide-activator factor, the concentration (1 mjM) of NaN3 that gave half-maximal activation with Mn2+ or Mg2+ was imilar. Thus, under some conditions guanylate cyclase can effectively use Mg2+ as a sole cation cofactor.

Adrenal Glands↗
PubMedDate not supplied

[Sodium azide as indirect nitric oxide donor: researches on the rat aorta isolated segments].

A comparative investigations of heme-containing enzymes inhibitors NaN3 and NaCN effects on the rat aorta isolated segments tone has shown that NaN3 in the range of very low concentrations from 10(-9) to 10(-6) M displays pharmacological activity characteristic of nitric oxide (NO) donors, which is inhibited by NaCN. The value of vasodilatation, caused by NaN3, was also decreased in the presence of soluble guanylate cyclase inhibitor ODQ (10(-5) M). It was found that H2O2 injection to physiological solution containing NaN3 and horseradish peroxidase or catalase lead to NO2- accumulation in it, which was blocked by NaCN. The nonenzymic NaN3 oxidization by hydrogen peroxide was not found in control experiments. NaN3 physiological activity dependent on NO-donating properties of this traditional inhibitor of heme-containing enzymes is discussed.

Animals↗
PubMed1977

Effects of sodium nitroprusside, nitroglycerin, and sodium azide on levels of cyclic nucleotides and mechanical activity of various tissues.

Three agents that activate guanylate cyclase, sodium nitroprusside, nitroglycerin and sodium axide, were examined for their effects on cyclic GMP and cyclic AMP accumulation and muscle motility with several tissues. All of these agents, except nitroglycerin with ventricle preparations, increased cyclic GMP levels and did not alter cyclic AMP in incubations of preparations of bovine tracheal smooth muscle, guinea pig tracheal chains, taenia cecum, atria and ventricle, and rat liver and cerebral cortex. Increases in cyclic GMP with these agents occurred with relaxation of smooth muscle preparations and without alteration in the contractility of atrial preparations. These observations support the hypothesis that cyclic GMP accumulation in smooth muscle may be related to relaxation rather than contraction as proposed previously. Relaxation with these agents is not associated with alterations in cyclic AMP levels. Increases in cyclic GMP levels in atrial preparations can also occur without changes in contractile force or rate of contraction.

Animals↗
PubMed1985

Quenching of carbohydrate reactions by azide.

Sodium azide, at concentrations that prevent development of microorganisms, interferes with the anthrone and phenol sulfuric acid reactions for carbohydrates, and with the glucose oxidase reaction. It does not affect copper reduction and the ortho-toluidine reaction.

Azides↗