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PubMed2006

Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon.

The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.

Adsorption↗

PubMed1994

Enzymatic properties, metal composition and SH-group reactivity of the light and heavy sarcoplasmic reticulum vesicles.

Light (LT) and heavy (TTC) microsomes were isolated from the fragmented sarcoplasmic reticulum (FSR) of rabbit skeletal muscle by sucrose gradient centrifugation. The amount of the protein components (ATPase, "feet proteins", calsequestrine) showed substantial differences between the light and heavy fractions. The amounts of calcium, magnesium and zinc were about 2-4 times higher in the TTC fraction, then those of the LT fraction. The activities of the Ca2+ + Mg2+ activated para-nitrophenyl-phosphatase and acetylcholin-esterase were (about 1.5 times) also higher in the TTC fraction compared to the LT fraction. The ratio of the Ca-transport vs. ATP was 2.1 in case of the LT and 0.6 in case of the TTC fraction. The number of titerable SH-groups of the LT fraction, measured in EGTA-medium containing Ca2+, was higher than those measured in the absence of Ca2+, while for the TTC fraction this number was higher when determined in the absence of Ca2+. We suppose that due to the higher amount of Ca2+ and Zn2+ in the TTC fraction those SH-groups which were present as Ca- or Zn-thiolates became titerable in EGTA-medium in the absence of Ca2+.

4-Nitrophenylphosphatase↗

PubMed1991

Hypochlorous acid mobilizes cellular zinc.

Neutrophil oxidants, in particular hypochlorous acid (HOCl), can cause injury to healthy tissues at sites of inflammation. Some of this injury may be caused by oxidant-induced mobilization of metals. We examined the ability of HOCl to mobilize Zn2+ in target tissues. Arterial endothelial cell cultures and heart tissue sections were incubated for 90 s in buffered saline, pH 7.3, containing a suspension of N-(6-methoxy-8-quinolyl)-p-toluenesulfonamide (100 nmol/mL), a Zn(2+)-specific fluorescent chelator, and were subsequently exposed to 200 microM HOCl for 5 min. The cellular fluorescence was analyzed histologically and showed a marked increase in intensity after HOCl treatment, which was indicative of an increase in cellular free Zn2+ concentration. Incubation of HOCl-treated tissues with dithiothreitol, a membrane-permeable metal chelator, caused a sharp decline in cellular fluorescence. This study shows for the first time that HOCl can mobilize cellular Zn2+. In view of the multiple cellular roles played by Zn2+, its mobilization by oxidants at sites of inflammation may contribute to the observed injury. The ability of dithiothreitol to chelate the mobilized Zn2+ suggests that it may be able to reverse Zn(2+)-mediated injury.

Aminoquinolines↗

PubMed1993

Zinc-specific N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide as a selective nontoxic fluorescence stain for pancreatic islets.

Separation of the endocrine from the exocrine pancreatic tissue by fluorescence activated sorting has been limited by the lack of an ideal fluorescent label for islet tissue. Our studies indicates the zinc-specific stain N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ), has characteristics ideal for use as a fluorescent label for islet tissue. Dispersed rat pancreas cells stained with TSQ produced bright blue fluorescence when excited by UV light (peak emission wavelength at 480 nm, maximal excitation at 365 nm). The fluorescence was specific for islet tissue as confirmed by counterstaining with the islet-specific stain dithizone and there was minimal background staining of exocrine tissue. Stained tissue remained brightly fluorescent for 2 hr, with some fading by 4 hr. Injection of TSQ into rats at a concentration sufficient to produce staining of islets produced no toxicity discernible at 4 months. The viability of isolated rat islets stained with TSQ was maintained as shown by supravital staining, in vitro secretion of insulin, and reversal of diabetes after transplantation of stained islets into diabetic syngeneic recipients.

Aminoquinolines↗

PubMed2002

Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes.

Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers.

Catalysis↗

PubMed2000

Zinc-enriched (ZEN) terminals in mouse spinal cord: immunohistochemistry and autometallography.

The general distribution of zinc-enriched (ZEN) terminals in mouse spinal cord was investigated at light microscopic level by means of zinc transporter-3 immunohistochemistry (ZnT3(IHC)) and zinc selenium autometallography (ZnSe(AMG)). Staining for ZnT3(IHC) corresponded closely to the ZnSe(AMG) staining. Both appeared as dense grains of variable sizes and densities in the gray matter with a characteristic segmental laminar pattern. The white matter was unstained but contained rows of stained terminals radiating from the gray matter. In the dorsal horn, laminae I, III and IV were heavily stained, whereas lamina II appeared as the least stained area in the gray matter. Moderate staining was seen in laminae V and VI. In the ventral horn, large ZnT3(IHC) and ZnSe(AMG) grains, known from previous papers to represent ZEN terminals, were observed related in particular to motor neuronal somata and big dendrites. These ZEN terminals in the ventral horn were in general larger than those in the dorsal horn. This is the first description of the pattern of ZEN terminals in mouse spinal cord.

Animals↗

PubMed2005

Modulation of cadmium-induced oxidative stress in Ceratophyllum demersum by zinc involves ascorbate-glutathione cycle and glutathione metabolism.

To understand the interaction between Zn, an essential micronutrient and Cd, a non-essential element, Cd-10 microM and Zn supplemented (10, 50, 100, and 200 microM) Cd 10 microM treated Ceratophyllum demersum L. (Coontail), a free floating freshwater macrophyte was chosen for the study. Cadmium at 10 microM concentration decreased thiol content, enhanced oxidation of ascorbate (AsA) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively, a clear indication of oxidative stress. Zinc supplementation to Cd (10 microM) treated plants effectively restored thiols, inhibited oxidation of AsA and GSH maintaining the redox molecules in reduced form. Cd-10 microM slightly induced ascorbate peroxidase (APX, E.C. 1.11.1.11) but inhibited monodehydroascorbate reductase (MDHAR, E.C. 1.6.5.4), dehydroascorbate reductase (DHAR, E.C. 1.8.5.1) and glutathione reductase (GR, E.C. 1.6.4.2), enzymes of ascorbate-glutathione cycle (AGC). Zn supplementation restored and enhanced the functional activity of all the AGC enzymes (APX, MDHAR, DHAR and GR). Gamma-glutamylcysteine synthetase (gamma-GCS, E.C. 6.3.2.2) was not affected by Cd as well as Zn, but Zn supplements increased glutathione-S-transferase (GST, E.C. 2.5.1.18) activity to a greater extent than Cd and simultaneously restored glutathione peroxidase (GSH-PX, E.C. 1.11.1.9) activity impaired by Cd toxicity. Zn-alone treatments did not change above investigated parameters. These results clearly indicate the protective role of Zn in modulating the redox status of the plant system through the antioxidant pathway AGC and GSH metabolic enzymes for combating Cd induced oxidative stress.

Ascorbic Acid↗

PubMed1996

Metal coordination environment and dynamics in 113cadmium bleomycin: relationship to zinc bleomycin.

The 13C chemical shifts of Cd- and ZnBlm A2 are almost identical throughout the entire molecule, suggesting that these structures adopt similar conformations. Nuclear magnetic resonance experiments with 113Cd-bleomycin have defined part of the metal-ligand environment of the molecule. Nitrogen atoms from the primary amine, pyrimidine, and imidazole are bound to 113Cd according to 13C spectra showing 113Cd-13C spin-spin couplings. Bound and free forms of the secondary amine nitrogen may be in equilibrium, as suggested by temperature-dependent 13C studies with Cd-bleomycin. In addition, a number of other carbon resonances are in chemical exchange over the temperature range 5-54 degrees C. The temperature dependence of the line widths of carbon atoms of Zn-bleomycin strongly resembles that of Cd-bleomycin. Examination of the 113Cd resonance as a function of temperature also supports the presence of at least two differently coordinated forms of cadmium in the molecule. According to the position of the 113Cd chemical shift, at most four nitrogen atoms are bound to Cd at low temperature. Titrations of 113Cd-bleomycin with chloride or acetate demonstrate that these anions can bind to major and minor forms of the structure and that a minor species exists which does not associate with chloride.

Antibiotics, Antineoplastic↗

PubMed2005

Stabilization of the non-canonical adenine-adeninium base pair by N(7) coordination of Zn(II).

A new zinc (II) compound with 9-ethyladenine (9-EtA) of formula [Zn(9-EtA-N7)Cl(3)](9-EtAH) has been synthesized and characterized by X-ray diffraction. Its X-structure consists of an Zn(II) anionic complex and 9-ethyladeninium as counteranion. The Zn(II) complex shows a distorted tetrahedral geometry in which three Cl and an 9-EtA coordinates through N(7) position are the ligands. An indirect chelation via intramolecular H-bond between N(6)H and an Cl ligand is present in the complex. The network of [Zn(9-EtA-N7)Cl(3)](9-EtAH) shows interesting features. Thus, self-association of coordinated adenine-adeninium takes place by H-bonding of N(6)-H...N(1) and N(6)-H...N(7), leading to a polymeric ribbon-like 1D supramolecular arrangement. Ab initio calculations have been applied in order to study the stability of the adenine-adeninium interaction due to the coordination of the Zn(II) to the N(7) position and to compare experimental and theoretical structural data.

Adenine↗

PubMed2003

Regulation of phytochelatin synthesis by zinc and cadmium in marine green alga, Dunaliella tertiolecta.

Although Cd(2+) is a more effective inducer of phytochelatin (PC) synthesis than Zn(2+) in higher plants, we have observed greater induction of PC synthesis by Zn(2+) than Cd(2+) in the marine green alga, Dunaliella tertiolecta. To elucidate this unique regulation of PC synthesis by Zn(2+), we investigated the effects of Zn(2+) and Cd(2+) on the activities of both phytochelatin synthase (PC synthase) and enzymes in the GSH biosynthetic pathway. PC synthase was more strongly activated by Cd(2+) than by Zn(2+), but the difference was not very big. On the other hand, gamma-glutamylcysteine synthetase (gamma-ECS) and glutathione synthetase (GS) were activated by both heavy metals, but their activities were higher in Zn-treated cells than in Cd-treated cells. Dose-dependent stimulation of intracellular reactive oxygen species (ROS) production was observed with Zn(2+), but not Cd(2+) treatment. These results suggest that Zn(2+) strongly promotes the synthesis of GSH through indirect activation of gamma-ECS and GS by stimulating ROS generation. This acceleration of the flux rate for GSH synthesis might mainly contribute to high level PC synthesis.

Aminoacyltransferases↗

PubMed2004

Dual opposite injection electrokinetic chromatography: nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias.

Dual opposite injection capillary electrophoresis (DOI-CE) is a family of CE techniques in which the sample is introduced into both ends of the capillary. For the analysis of compounds with widely varying pKa values using a voltage-driven separation scheme, DOI-CE is superior to conventional CE with sample introduction at only one end of the capillary due to DOI-CE's broader elution window. To enhance the DOI-CE separation, a running buffer with a microemulsion system was developed. Since DOI-CE works best under conditions of low electroosmotic flow (EOF), the suppression of EOF via the addition of a multiply charged cation (e.g., Zn2+) to the buffer was investigated, and was found to suppress the EOF effectively at moderate concentrations (2.5-10 mM). Three different dual opposite injection modes were studied: simultaneous electrokinetic injection, sequential electrokinetic injection, and sequential hydrodynamic injection. The injection bias in the first two electrokinetic injection modes was compared with the sequential hydrodynamic injection. Corrections in the bias of the electrokinetic injections were discussed, and an improved approach was suggested. Finally, the effect of the relative concentration of the multiply charged cation in the sample plug and running buffer on the peak shape of co-electroosmotic and counter-electroosmotic ions was examined, and found to be much more influential on the latter.

Anions↗

PubMed2002

Understanding ship-grounding impacts on a coral reef: potential effects of anti-foulant paint contamination on coral recruitment.

The 184 m cargo ship Bunga Teratai Satu collided with Sudbury Reef, part of the Great Barrier Reef and remained grounded for 12 days. The ship was re-floated only 3 days prior to the November 2000 mass coral spawning. No cargo or fuel was lost but the impact resulted in significant contamination of the reef with anti-foulant paint containing tributyltin (TBT), copper (Cu) and zinc (Zn). Larvae of the reef-building scleractinian coral Acropora microphthalma were exposed to various concentrations of sediment collected from the grounding site in replicated laboratory experiments. Two experiments were performed, both of which used varying ratios of contaminated and control site sediment in seawater as treatments. In the first experiment, the influence of contaminated sediment on larval competency was examined using metamorphosis bioassays. In the second, the effect of contaminated sediment upon larval recruitment on pre-conditioned terracotta tiles was assessed. In both experiments, sediment containing 8.0 mg kg(-1) TBT, 72 mg kg(-1) Cu and 92 mg kg(-1) Zn significantly inhibited larval settlement and metamorphosis. At this level of contamination larvae survived but contracted to a spherical shape and swimming and searching behaviour ceased. At higher contamination levels, 100% mortality was recorded. These results indicate that the contamination of sediment by anti-fouling paint at Sudbury Reef has the potential to significantly reduce coral recruitment in the immediate vicinity of the site and that this contamination may threaten the recovery of the resident coral community unless the paint is removed.

Animals↗

PubMed1994

Induction of AP-1 (Fos/Jun) by chemical agents mediates activation of glutathione S-transferase and quinone reductase gene expression.

A regulatory element, EpRE, was found to be responsible for the induction of mouse glutathione S-transferase (GST) Ya gene expression by a variety of chemical agents such as planar aromatic hydrocarbons, diphenols, phorbol ester, phenobarbital and electrophilic compounds. The EpRE is composed of two adjacent AP-1-like binding sites and was recently found to be activated by Fos/Jun heterodimeric complex (AP-1). In this report we show that regulatory elements ARE, previously demonstrated to mediate the chemical induction of rat GST Ya and quinone reductase genes, have a similar structure with EpRE and are activated by Fos/Jun complex. The activation of GST Ya and quinone reductase genes by a variety of chemical inducers is found to be associated with an increase in AP-1 binding activity. We present evidence that chemical agents induce expression of c-fos and c-jun proto-oncogenes and an enhanced synthesis of protein components of AP-1 complex. We suggest that the increased synthesis of AP-1 complex followed by an AP-1-mediated transcriptional activation of GST Ya and quinone reductase genes may provide a molecular mechanism for the induction of these drug-metabolizing enzymes by chemical agents.

Arsenates↗

PubMed1994

Flux of intracellular labile zinc during apoptosis (gene-directed cell death) revealed by a specific chemical probe, Zinquin.

BACKGROUND: The transition metal Zn(II) is thought to regulate cell and tissue growth by enhancing mitosis (cell proliferation) and suppressing the counterbalancing process of apoptosis (gene-directed cell death). To investigate the role of Zn(II) further, we have used a UV-excitable Zn(II)-specific fluorophore, Zinquin. The ester group of Zinquin is hydrolyzed by living cells, ensuring its intracellular retention; this allows the visualization and measurement of free or loosely-bound (labile) intracellular Zn(II) by fluorescence video image analysis or fluorimetric spectroscopy. RESULTS: Here we show that in cells undergoing early events of apoptosis, induced spontaneously or by diverse agents, there is a substantial increase in their Zinquin-detectable Zn(II). This increase occurred in the absence of exogenous Zn(II) and before changes in membrane permeability, consistent with a release of Zn(II) from intracellular stores or metalloproteins rather than enhanced uptake from the medium. We propose that there is a major redistribution of Zn(II) during the induction of apoptosis, which may influence or precipitate some of the later biochemical and morphological changes. CONCLUSIONS: The phenomenon of Zn(II) mobilization, revealed by Zinquin, presents a new element in the process of apoptosis for investigation and may permit rapid and sensitive identification of apoptotic cells, particularly in those tissues where their frequency is low.

Animals↗

PubMed2000

Triethoxysilyl-substituted aminoethanethiol ligands for zinc and cadmium complexes and aminoethanethiol-modified silica gel. Evaluation of the corresponding supported molecular trap for metallic pollutant uptake (Cd2+, Hg2+ and Pb2+).

The reaction of 2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, a) and 1-methyl-2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, b) with ZnX2 and CdX2 (X = Cl, Br, I, NO3) in tetrahydrofuran (THF) or CH2Cl2 gives several complexes depending on the experimental conditions. Elemental analyses, IR, Raman, 13C[1H], 1H NMR and mass spectroscopies indicated the formation of mononuclear and dinuclear complexes. In the absence of NEt3 as proton quencher, the protonated ligands react in their zwitterionic form giving dinuclear [M(LH)X2]2 [M = Zn (1), Cd (2); LH = a, b; X = Cl, Br, I] or mononuclear M(NO3)2(LH)2 [M = Zn (5), Cd (6); LH = a] complexes. In both cases, coordination occurs through the S atoms, the ligands acting as terminal and bridging species. With NEt3, the deprotonated ligands are chelated through their N and S atoms and bridging occurs through the S atoms in [MLX]2 [M = Zn (3), Cd (4); LH = a; X = Cl, Br] complexes. The LH ligand is chemically grafted onto silica, the procedure optimized and the resulting material characterized by 13C and 29Si cross-polarization, magic-angle spinning (CP-MAS) NMR and DRIFT. This material is evaluated as a supported molecular trap for binding heavy metals (Cd2+, Hg2+, Pb2+) in aqueous solution. In both batch and column processes, it appears that Hg2+ and Pb2+ are trapped more than Cd2+, but in all cases values lower than those allowed were obtained.

Cadmium↗

PubMed1995

Heterogenous binding of 3H-remoxipride to membranes of rat liver and brain.

The binding of the antipsychotic agent 3H-remoxipride to membranes of rat liver and brain (whole brain and cerebellum) was studied with filtration technique. Saturable high affinity binding was obtained for all three types of tissue preparations. Heterogenous binding sites were found since various types of compounds inhibited the binding of 3H-remoxipride with shallow dose-response curves. In the liver preparation it was possible to differentiate between two different binding sites. One site, called rem1, was defined with 100 nM alaproclate and bound sigma 2 ligands with high affinity, e.g. haloperidol, GBR 12909, DTG and (+)-3-PPP. High correlation (r = 0.93) was obtained between the inhibition of the binding of 3H-remoxipride to the rem1 site and the inhibition of the binding of the sigma ligand 3H-DTG reported previously (Ross 1991), indicating that the rem1 site is identical to a sigma 2-like binding site. The other 3H-remoxipride binding site in the rat liver, rem2 appears to be identical to the site binding alaproclate, proadifen and cocaine with high affinity. Cd2+ and Zn2+ were potent inhibitors of both binding sites, Cd2+ particularly of rem2 binding and Zn2+ preferably of rem1 binding. The apparent Bmax (pmol/g original tissue) and KD (nM) values for rem1 binding were 441 +/- 43 and 80 +/- 14, and for rem2 binding 727 +/- 116 and 95 +/- 6. The binding of 3H-remoxipride to the brain preparations was also inhibited with shallow dose-response curves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2005

Arsenite binding to synthetic peptides based on the Zn finger region and the estrogen binding region of the human estrogen receptor-alpha.

We selected the estrogen receptor protein for study because of prior results indicating that arsenite is a "potential nonsteroidal environmental estrogen". We utilized radioactive (73)As-labeled arsenite and vacuum filtration methodology to determine the binding affinity of arsenite to synthetic peptides. A zinc finger region containing four free sulfhydryls and the hormone binding region containing three free sulfhydryls based on the human estrogen receptor-alpha were studied. Peptide 15 (RYCAVCNDYASGYHYGVWSCEGCKA) bound arsenite with a K(d) of 2.2 microM and B(max) (maximal binding capacity) of 89 nmol/mg protein. Peptide 10 (LECAWQGKCVEGTEHLYSMKCKNV) had a K(d) of 1.3 microM and B(max) of 59 nmol/mg protein. In contrast, the monothiol peptide 19 (LEGAWQGKGVEGTEHLYSMKCKNV) bound arsenite with a higher K(d) of 124 microM and a B(max) of 26 nmol/mg protein. In our studies, amino acids other than cysteine (including methionine and histidine) did not bind arsenite at all. Peptides modeled on the estrogen receptor with two or more nearby free sulfhydryls (two or five intervening amino acids) had low K(d) values in the 1-4 microM range. Peptides containing single sulfhydryls or two sulfhydryls spaced 17 amino acids apart had higher K(d) values in the 100-200 microM range, demonstrating lower affinity. With the exception of peptide 24 which had an unusually high B(max) value of 234 nmol/mg, the binding capacity of the studied peptides was proportional to the number of free cysteines. Binding of trivalent arsenicals to peptides and proteins can contribute to arsenic toxicity and carcinogenicity via altered peptide/protein structure and enzyme function.

Arsenites↗

PubMed2000

Routes of zinc entry in mouse cortical neurons: role in zinc-induced neurotoxicity.

Exposure of central neurons to Zn2+ triggers neuronal death. The routes of Zn2+ entry were investigated in living cortical neurons from the mouse using the specific Zn2+ fluorescent dye N-(6-methoxy-8-quinolyl)-p-toluene sulphonamide (TSQ), which preferentially detects membrane-bound Zn2+. Exposure of cortical neurons to increasing concentrations of Zn2+ (1-100 microM) induced a progressive increase in the fluorescence of TSQ. This fluorescence signal was not attenuated by the permeation of plasma membrane with digitonin. Accordingly, the major part of TSQ fluorescence (two-thirds) was associated to the particulate fraction of cortical neurons exposed to Zn2+. These results suggest that Zn2+ detected with TSQ in neurons is mainly bound to membranes. TSQ fluorescence measured in neurons exposed to 3 microM Zn2+ was enhanced by Na+-pyrithione, a Zn2+ ionophore, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), N-methyl-D-aspartate (NMDA) or KCl-induced depolarization. However, in the absence of any treatment, TSQ labelling of neurons exposed to 3 microM Zn2+ was only decreased by NMDA receptor antagonists, whereas it remained unaltered in the presence of antagonists of AMPA receptors or L-type voltage-gated Ca2+ channels. Zn2+ entry through NMDA receptors did not contribute to Zn2+-induced neuronal death, as it was prevented by antagonists of NMDA receptors only when they were added after the Zn2+ exposure. Finally, Zn2+ induced a delayed accumulation of extracellular glutamate which might be responsible for the delayed NMDA receptor activation that leads to neuronal death.

Adenosine Triphosphate↗