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Sample records for calcium-and-magnesium ion-dependent adenosine

  1. Effects of calcium and magnesium on strontium distribution coefficients

    USGS Publications Warehouse

    Bunde, R.L.; Rosentreter, J.J.; Liszewski, M.J.; Hemming, C.H.; Welhan, J.

    1997-01-01

    The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K(d)'s) using simulated wastewater solutions prepared at pH 8.0??0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K(d)'s ranged from 12??1 to 85??3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment.

  2. Automatic photometric titrations of calcium and magnesium in carbonate rocks

    USGS Publications Warehouse

    Shapiro, L.; Brannock, W.W.

    1955-01-01

    Rapid nonsubjective methods have been developed for the determination of calcium and magnesium in carbonate rocks. From a single solution of the sample, calcium is titrated directly, and magnesium is titrated after a rapid removal of R2O3 and precipitation of calcium as the tungstate. A concentrated and a dilute solution of disodium ethylenediamine tetraacetate are used as titrants. The concentrated solution is added almost to the end point, then the weak solution is added in an automatic titrator to determine the end point precisely.

  3. Stability and broad-sense heritability of mineral content in potato: calcium and magnesium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium and magnesium are two minerals with prominent roles in animal and plant metabolism. Advanced potato breeding lines were found to contain between 266 and 944 µg per gram fresh weight of calcium and between 705 1089 µg per gram fresh weight of magnesium. All trials had significant genotype b...

  4. Split ejaculation study: semen parameters and calcium and magnesium in seminal plasma

    PubMed Central

    Valsa, James; Khan, Pulikkal Sahab; Sumangala, Balakrishnan; Gondalia, Meenaxi

    2012-01-01

    Objectives Male infertility is on the rise. Artificial insemination is an option in many cases like oligozoospermia or oligoasthenozoospermia. Homologous insemination is helpful for some couples in whom sperm count is low. This study was aimed to understand the most suitable portion of split ejaculate for insemination and also the level of calcium and magnesium in each split. Materials and methods A total number of 31 normal and clinically healthy adults participated in this study. They were instructed to maintain abstinence for 2-5 days prior to sample collection in three splits. Each split was evaluated as if it were a whole sample, following WHO criteria. Seminal plasma was separated. Calcium and magnesium levels were measured in seminal plasma and spermatozoa of each split. Results The split ejaculate study revealed that the first portion contained a higher number of spermatozoa with better motility than the 2nd and 3rd splits. Similarly, the level of calcium and magnesium in seminal plasma and spermatozoa was greater in the first split, followed by 2nd and 3rd splits. Conclusion The presented split ejaculate study has shown the first ejaculate as superior in quality in terms of total sperm count and percentage of active motility. The first split of ejaculation is recommended for homologous artificial insemination in case of oligozoospermia and oligoasthenozoospermia. This study has also shown that a major portion of two important elements, calcium and magnesium, is contributed by the prostate gland. PMID:24578965

  5. Comparison of Serum Calcium and Magnesium Between Preeclamptic and Normotensive Pregnant Nigerian Women in Abakaliki, Nigeria

    PubMed Central

    Ugwuja, EI; Famurewa, AC; Ikaraoha, CI

    2016-01-01

    Background: Evidence suggests the involvement of calcium and magnesium metabolism in the pathophysiology of preeclampsia. However, findings from studies are heterogenous and inconsistent. Aim: The study aimed to compare the total serum calcium and magnesium levels in preeclamptic women with that of normotensive pregnant women. Subjects and Methods: A cross-sectional subjects of eighty pregnant women living in Abakaliki, Ebonyi state, South-East Nigeria, were recruited into the study. The present study compared serum calcium and magnesium in forty preeclamptic (cases) and forty normotensive (control) pregnant women matched for age, parity, and socioeconomic status. Serum calcium and magnesium levels were measured using atomic absorption spectrophotometer. Statistical analysis was done using SPSS Version 20 statistical software. Differences between means were compared using Student's t-test with P < 0.05 considered as statistically significant. Results: While the mean serum calcium was comparable between preeclamptic and normotensive pregnant women (13.99 [3.29] vs. 14.02 [5.68] μg/dl), the preeclamptic pregnant women have significantly (P < 0.001) lower serum magnesium in comparison to their normotensive counterparts (3.22 [1.05] vs. 4.15 [0.78]). Conclusion: It may be concluded that serum magnesium seems to play a crucial role in the pathophysiology of preeclampsia in this environment. PMID:27144074

  6. Impact of Testosterone, Zinc, Calcium and Magnesium Concentrations on Sperm Parameters in Subfertile Men

    NASA Astrophysics Data System (ADS)

    Aydemir, Birsen; Kiziler, Ali Riza; Onaran, Ilhan; Alici, Bülent; Özkara, Hamdi; Akyolcu, Mehmet Can

    2007-04-01

    To investigate the impact of testosterone, zinc, calcium and magnesium concentrations in serum and seminal plasma on sperm parameters. There were significant decrease in sperm parameters, serum and seminal plasma zinc levels in subfertile males. It indicates zinc has a essential role in male infertility; the determination the level of zinc during infertility investigation is recommended.

  7. A field method for the determination of calcium and magnesium in limestone and dolomite

    USGS Publications Warehouse

    Shapiro, Leonard; Brannock, Walter Wallace

    1957-01-01

    The method is an adaptation of a procedure described by Betz and Noll1 in 1950. Calcium and magnesium are determined by visual titration using Versene (disodium ethylenediamine tetraacetate) with Murexide (ammonium purpurate) as the indicator for calcium and Eriochrome Black T as the indicator for magnesium.

  8. Metabolism of calcium and magnesium in liver during acute thioacetamide intoxication.

    PubMed

    Anghileri, L J

    1976-09-01

    The metabolism of calcium and magnesium in liver of thioacetamide treated rats has been studied. A change in the semipermeability of the cell membrane to calcium, magnesium, sodium and potassium was observed. The variations in the concentration of extra- and intracellular cations indicates that an undiscriminated in- and outflux of those ions takes place at the time of highest calcium deposition. This change in the cell membrane permeability seems to be related to modifications in the phospholipid metabolism. An increased incorporation of 32P into the acidic phospholipids (phosphatidyl ethanolamine and phosphatidyl serine) suggests their involvement in the physiological changes of the cell membrane. The results also point out the existence of a hormonally determined susceptibility of the cell membrane to undergo those changes. PMID:1002347

  9. Simultaneous determination of inorganic anions, calcium and magnesium by suppressed ion chromatography.

    PubMed

    García-Fernández, Ruben; García-Alonso, J Ignacio; Sanz-Medel, Alfredo

    2004-04-01

    Suppressed conductimetric detection ion chromatography (IC) was investigated for the separation and detection of common inorganic anions, calcium and magnesium by anion-exchange chromatography using a sodium carbonate-EDTA mobile phase. The formation of anionic Ca2+ -EDTA and Mg2+ -EDTA complexes allowed its separation from other inorganic anions opening the way for their simultaneous determination in a single chromatographic run. The effect of the pH, carbonate and EDTA concentrations in the eluent and the previous addition of EDTA to the samples has been studied. The optimised experimental conditions were applied to the determination of Ca2+ and Mg2+ in mineral waters with results in agreement with alternative ICP-MS methodologies. PMID:15072297

  10. Continental weathering following a Cryogenian glaciation: Evidence from calcium and magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Kasemann, Simone A.; Pogge von Strandmann, Philip A. E.; Prave, Anthony R.; Fallick, Anthony E.; Elliott, Tim; Hoffmann, Karl-Heinz

    2014-06-01

    A marked ocean acidification event and elevated atmospheric carbon dioxide concentrations following the extreme environmental conditions of the younger Cryogenian glaciation have been inferred from boron isotope measurements. Calcium and magnesium isotope analyses offer additional insights into the processes occurring during this time. Data from Neoproterozoic sections in Namibia indicate that following the end of glaciation the continental weathering flux transitioned from being of mixed carbonate and silicate character to a silicate-dominated one. Combined with the effects of primary dolomite formation in the cap dolostones, this caused the ocean to depart from a state of acidification and return to higher pH after climatic amelioration. Differences in the magnitude of stratigraphic isotopic changes across the continental margin of the southern Congo craton shelf point to local influences modifying and amplifying the global signal, which need to be considered in order to avoid overestimation of the worldwide chemical weathering flux.

  11. STUDYING THE EFFECTS OF CALCIUM AND MAGNESIUM ON SIZE-DISTRIBUTED NITRATE AND AMMONIUM WITH EQUISOLV II. (R823186)

    EPA Science Inventory

    Abstract

    A chemical equilibrium code was improved and used to show that calcium and magnesium have a large yet different effect on the aerosol size distribution in different regions of Los Angeles. In the code, a new technique of solving individual equilibrium equation...

  12. Chronic dietary fiber supplementation with wheat dextrin does not inhibit calcium and magnesium absorption in premenopausal and postmenopausal women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This placebo-controlled, randomized, crossover clinical study examined the effect of chronic wheat dextrin intake on calcium and magnesium absorption. Forty premenopausal and post menopausal women (mean +/- SD age 49.9 +/- 9.8 years)consumed wheat dextrin or placebo (15 g/day) for 2 weeks prior to 4...

  13. Fully automated spectrophotometric procedure for simultaneous determination of calcium and magnesium in biodiesel.

    PubMed

    Shishov, Andrey Y; Nikolaeva, Larisa S; Moskvin, Leonid N; Bulatov, Andrey V

    2015-04-01

    An easily performed stepwise injection (SWIA) procedure based on on-line dilution of biodiesel samples and the formation of color-forming calcium (II) and magnesium (II) complexes with Eriochrome Black T (EBT) in an organic medium followed by spectrophotometric determination is presented. A sample of biodiesel was placed at the bottom of a mixing chamber connected to an automatic SWIA manifold. Isopropyl alcohol was used as the diluent under bubbling. The solution was submitted for on-line spectrophotometric simultaneous determination of calcium and magnesium based on the classic least-square method. The linear ranges were from 2 to 20 μg g(-1) and from 1.2 to 12 μg g(-1), and the detection limits, calculated as 3 s for a blank test (n=5), were found to be 0.6 μg g(-1) for calcium and 0.4 μg g(-1) for magnesium. The sample throughput was 30 h(-1). The method was successfully applied to the analysis of biodiesel samples. PMID:25640136

  14. Dynamical behaviors of structural, constrained and free water in calcium- and magnesium-silicate-hydrate gels

    DOE PAGESBeta

    Le, Peisi; Fratini, Emiliano; Ito, Kanae; Wang, Zhe; Mamontov, Eugene; Baglioni, Piero; Chen, Sow-Hsin

    2016-01-28

    We present the hypothesis that the mechanical properties of cement pastes depend strongly on their porosities. In a saturated paste, the porosity links to the free water volume after hydration. Structural water, constrained water, and free water have different dynamical behavior. Hence, it should be possible to extract information on pore system by exploiting the water dynamics. With our experiments we investigated the slow dynamics of hydration water confined in calcium- and magnesium-silicate-hydrate (C-S-H and M-S-H) gels using high-resolution quasi-elastic neutron scattering (QENS) technique. C-S-H and M-S-H are the chemical binders present in calcium rich and magnesium rich cements. Wemore » measured three M-S-H samples: pure M-S-H, M-S-H with aluminum-silicate nanotubes (ASN), and M-S-H with carboxyl group functionalized ASN (ASN-COOH). A C-S-H sample with the same water content (i.e. 0.3) is also studied for comparison. We found that structural water in the gels contributes to the elastic component of the QENS spectrum, while constrained water and free water contribute the quasi-elastic component. The quantitative analysis suggests that the three components vary for different samples and indicate the variance in the system porosity, which controls the mechanical properties of cement pastes.« less

  15. Calcium and magnesium levels in isolated mitochondria from human cardiac biopsies.

    PubMed

    Saetersdal, T; Engedal, H; Røli, J; Myklebust, R

    1980-01-01

    A non-enzymatic method is presented for isolating mitochondria from small-sized human cardiac samples, including ventricular needle biopsies of 15-25 mg of wet weight. Electron microscopy demonstrates that these fractions are rich in structurally well preserved mitochondria. Calcium and magnesium levels of fractions are determined by atomic absorption flame spectroscopy. Comparative analyses are made in similar fractions of the mouse ventricle. Calcium concentrations of mitocondria isolated in the presence of ruthenium red do not differ significantly between the human auricle and ventricle, averaging 61 nmol Ca/mg protein and 68 nmol Ca/mg protein, respectively. Mitochondrial calcium level is lower in the mouse ventricular fractions, averaging 7 nmol Ca/mg protein. Mitochondrial magnesium amounts to slightly less than 60% of the calcium levels in the human heart, while it exceeds the calcium level by more than 100 per cent in the mouse heart. There is no significant difference of mitochondrial calcium between normal auricles, and, auricles of patients with increased right atrial mean pressure and/or volume overload. PMID:7410123

  16. Dynamical behaviors of structural, constrained and free water in calcium- and magnesium-silicate-hydrate gels

    SciTech Connect

    Le, Peisi; Fratini, Emiliano; Wang, Zhe; Mamontov, Eugene; Baglioni, P; Chen, Sow-Hsin

    2016-01-01

    Hypothesis: The mechanical properties of cement pastes depend strongly on their porosities. In a saturated paste, the porosity links to the free water volume after hydration. Structural water, constrained water, and free water have different dynamical behavior. Hence, it should be possible to extract information on pore system by exploiting the water dynamics. Experiments: We investigated the slow dynamics of hydration water confined in calcium- and magnesium-silicate-hydrate (C-S-H and M-S-H) gels using high-resolution quasi-elastic neutron scattering (QENS) technique. C-S-H and M-S-H are the chemical binders present in calcium rich and magnesium rich cements. We measured three M-S-H samples: pure M-S-H, M-S-H with aluminum-silicate nanotubes (ASN), and M-S-H with carboxyl group functionalized ASN (ASN-COOH). A C-S-H sample with the same water content (i.e. 0.3) is also studied for comparison. Findings: Structural water in the gels contributes to the elastic component of the QENS spectrum, while constrained water and free water contribute the quasi-elastic component. The quantitative analysis suggests that the three components vary for different samples and indicate the variance in the system porosity, which controls the mechanical properties of cement pastes. (C) 2016 Elsevier Inc. All rights reserved.

  17. Self-association of calcium and magnesium complexes of dentin phosphophoryn.

    PubMed

    Marsh, M E

    1989-01-10

    Self-association of rat dentin phosphophoryn in the presence of calcium and magnesium ions was examined by chemical cross-linking and electron microscopy. Highly phosphorylated phosphophoryn (HP) binds a maximum of 1.33 calcium ions or 1.07 magnesium ions per organic phosphate residue at pH 7.4-8.0. The Ca-HP complexes are predominantly linear when the calcium content of the complex is less than about 65% of the saturation level. At higher calcium levels, the protein has a folded conformation, and transient protein-protein interactions occur. The equilibrium mixture of monomers and oligomers is predominantly monomeric unless the protein is saturated with calcium. The saturated Ca-HP complex forms discrete high molecular weight particles about 25 nm in diameter. The particles are electrically neutral and generally occur in clusters. Mg-HP complexes appear predominantly linear by electron microscopy at all concentrations of bound magnesium up to about 99% of the saturation level; however, protein-protein interaction is measurable when the magnesium content is as little as 65% of the saturation level. At saturation, Mg-HP complexes form high molecular weight particles which are negatively charged. Because of the negative charge, these particles form a stable colloidal suspension and have a rather stellate configuration. PMID:2706258

  18. Dietary calcium and magnesium in the development of hypertension in the spontaneously hypertensive rat

    SciTech Connect

    Evans, G.; Weaver, C.M.; Harrington, D.D.; Babbs, C.F.

    1986-03-01

    The role of dietary calcium and magnesium in attenuation of hypertension was studied in 9 groups of 9 spontaneously hypertensive rats ages 8 to 31 weeks. The animals were fed AIN 76 semipurified diets altered in calcium (0.075%, 0.5%, and 2.5%) and magnesium (0.01%, 0.05%, and 0.75%) using a 3 x 3 factorial design. An inverse relationship between dietary calcium and systolic blood pressure as determined by the photoelectric tail cuff method became significant (p<0.05) after 12 weeks. Repeated measures analysis of variance indicated that dietary magnesium had no effect on systolic blood pressure; no calcium x magnesium interaction was observed. Total and ultrafiltrable serum calcium had a significant inverse correlation with blood pressure (-0.4642, p = .001 and -0.5568, p = .001 respectively). Total and ultrafiltrable serum magnesium reflected dietary magnesium concentration. Magnesium deficiency signs, deposition of calcium in kidneys, and histological lesions were observed in high calcium fed groups receiving normal and low levels of magnesium. Thus, a lowering of blood pressure by calcium supplementation without concomitant magnesium supplementation was accompanied by biochemical and histologic abnormalities in this animal model.

  19. Calcium and magnesium interference studies for the binding of heavy metal ions in solution by Medicago sativa (alfalfa)

    SciTech Connect

    Gardea-Torresdey, J.L.; Tiemann, K.J.; Gonzalez, J.H.; Henning, J.A.; Townsend, M.S.

    1996-12-31

    Previous batch laboratory experiments performed to determine the potential ability of seven different varieties of Medicago sativa (alfalfa) revealed that the African shoots population was able to efficiently bind copper(II) and nickel(II) from aqueous solutions. Batch laboratory interference studies were performed with various calcium and magnesium concentrations (0.1 mM to 1 M) in order to ascertain the effects of these ions on the heavy metal binding ability of African alfalfa shoots. Results from these studies have shown that calcium and magnesium did not seriously reduce the binding of copper(II) and lead(II) to African alfalfa shoots. However, high concentrations of calcium and magnesium significantly reduced chromium(III), cadmium(II), nickel(II), and zinc(II) binding to African shoots. In addition, all these experiments were repeated maintaining the ionic strength constant, and similar results were obtained. Interference studies were also conducted in order to determine the effects of hard cations under flow conditions with silica-immobilized African alfalfa shoots. The information obtained from these studies will be useful for an innovative method of heavy metal ion removal and recovery from contaminated waters.

  20. Dietary calcium and magnesium intakes and the risk of type 2 diabetes: the Shanghai Women's Health Study123

    PubMed Central

    Villegas, Raquel; Gao, Yu-Tang; Dai, Qi; Yang, Gong; Cai, Hui; Li, Honglan; Zheng, Wei; Shu, Xiao Ou

    2009-01-01

    Background: Diet plays a key role in the development of type 2 diabetes (T2D), but little is known about the contributions of specific nutrients in populations in which dietary patterns differ from Western populations. Objective: We examined associations between calcium and magnesium intakes and the risk of T2D in a Chinese population. Design: We used data from a population-based, prospective study of 64,191 women who were free of T2D or other chronic diseases at study recruitment and were living in urban Shanghai, China. Dietary intake, physical activity, and anthropometric measurements were assessed through in-person interviews. A Cox regression model was used to evaluate the association of the exposures under study with the risk of T2D. Results: An inverse association between calcium and magnesium intakes and T2D risk was observed. The relative risks for the lowest to the highest quintiles of calcium intake were 1.00, 0.82, 0.73, 0.67, and 0.74 (P for trend < 0.001), and for magnesium they were 1.00, 0.84, 0.84, 0.79, and 0.86 (P for trend < 0.001). Milk intake was also inversely associated with the risk of T2D. Conclusion: Our data suggest that calcium and magnesium intakes may protect against the development of T2D in this population. PMID:19225116

  1. Effect of Calcium and Magnesium Ions on the Susceptibility of Pseudomonas Species to Tetracycline, Gentamicin Polymyxin B, and Carbenicillin

    PubMed Central

    D'Amato, Richard F.; Thornsberry, Clyde; Baker, Carolyn N.; Kirven, Linda A.

    1975-01-01

    The effect of calcium and magnesium on the susceptibility of 13 species of Pseudomonas to tetracycline, gentamicin, polymyxin B, and carbenicillin was measured. The majority of the minimum inhibitory concentrations (MICs) of these antibiotics was increased if these cations were added to the test media. The increases in MICs caused by calcium or magnesium were similar, but the combination of both ions generally caused a greater change than either alone. Although the MIC of polymyxin B was most affected by calcium and magnesium, its interpretive susceptibilities (i.e., whether susceptible or resistant) were least changed. Susceptibility tests on Pseudomonas species probably should be done with Muller-Hinton broth supplemented with physiological concentrations of calcium and magnesium to better approximate the in vivo activity of these antibiotics. When the susceptibility tests were performed with Mueller-Hinton agar, the MICs were slightly less than those obtained with Mueller-Hinton broth supplemented with both cations but greater than those obtained with Mueller-Hinton broth supplemented with individual cations. PMID:167658

  2. Synthesis and Structural Studies of Calcium and Magnesium Phosphinate and Phosphonate Compounds

    NASA Astrophysics Data System (ADS)

    Bampoh, Victoria Naa Kwale

    The work presented herein describes synthetic methodologies leading to the design of a wide array of magnesium and calcium based phosphinate and phosphonates with possible applications as bone scaffolding materials or additives to bone cements. The challenge to the chemistry of the alkaline earth phosphonate target compounds includes poor solubility of compounds, and poorly understood details on the control of the metal's coordination environment. Hence, less is known on phosphonate based alkaline earth metal organic frameworks as compared to transition metal phosphonates. Factors governing the challenges in obtaining crystalline, well-defined magnesium and calcium solids lie in the large metal diameters, the absence of energetically available d-orbitals to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray quality crystals of the reaction products to allow for structural elucidation of the novel compounds. Various methodologies to aid in crystal growth including hydrothermal methods and gel crystallization were employed. We have used phosphinate and phosphonate ligands with different number of phosphorus oxygen atoms as well as diphosphonates with different linker lengths to determine their effects on the overall structural features. An interesting correlation is observed between the dimensionality of products and the increasing number of donor oxygen atoms in the ligands as we progress from phosphinic acid to the phosphorous acids. As an example, monophosphinate ligand only yielded one-dimensional compounds, whereas the phosphonates crystallize as one and two-dimensional compounds, and the di- and triphosphonate based compounds display two or three-dimensional geometries. This thesis provides a selection of calcium and magnesium compounds with one-dimensional geometry, as represented in a calcium phosphinate to novel

  3. Dissolved Calcium and Magnesium Carbonates Promote Arsenate Release From Ferrihydrite in Flow Systems

    NASA Astrophysics Data System (ADS)

    Saalfield, S. L.; Bostick, B. C.

    2007-12-01

    Field data from water systems around the world have shown that arsenic can reach toxic concentrations in dynamic groundwater systems. This is generally in contrast to analogous static systems at circumneutral pH, where arsenic is strongly retained by sorption to iron (hydr)oxides. Our research examines the effect of calcium and magnesium carbonates on As(V) mobility. In both dynamic flow and static experiments, arsenate was pre- sorbed to poorly crystalline iron hydroxides (1-10% sorption capacity), with varying aqueous compositions including calcium, magnesium, carbonate, sulfate, lactate, and other common groundwater species (pH 7.5-8). Thus we investigated how the dissolution of common carbonate minerals, specifically CaCO3 and MgCO3, affect arsenic behavior in the context of groundwater solutions. Under static (batch) conditions, no measurable arsenic (<10 μg/L) is released into solutions containing alkaline earth metals (AEMs) and carbonates. When elevated concentrations of AEMs and carbonate are introduced by dynamic flow, however, arsenic is mobilized at up to 500 μg/L, releasing significant proportions the total arsenic present. This is only the case when both of these species are present; with other common ion pairs, little to no arsenic is released. These results indicate that arsenate adsorption is kinetically controlled under flow conditions, resulting in very different mobility relative to otherwise equivalent static systems. Furthermore, the combination of alkaline earth metals and carbonates promotes As(V) mobility in column-based systems. We propose that these phenomena indicate a combination of physical and chemical effects by which diffusion limitation becomes dominant in limiting arsenic sorption in flow systems. Many carbonate-buffered aquifers, as well as those undergoing rapid mineralization of organic matter, could be affected by these processes of AEM-carbonate-limited sorption and increased arsenic mobility.

  4. Calcium and magnesium in exocrine secretion--an X-ray microanalytical study

    SciTech Connect

    Roomans, G.M.; Barnard, T.

    1982-01-01

    Calcium and magnesium distribution in mammalian exocrine glands under resting, stimulated and pathological conditions was investigated by X-ray microanalysis of thick and ultrathin cryosections. Ultrathin sections were cut from tissue frozen in the presence of a polymer cryoprotectant, dextran. The effect of this treatment on isolated rabbit pancreas. Dextran caused a disturbance in water and ion transport, partly due to an osmotic effect and the impermeability of the pancreatic epithelium to dextran; this does, however, not necessarily invalidate intracellular measurements on frozen-dried sections. Cholinergic stimulation of the rat pancreas caused a change of Ca distribution from the basal to the apical part of the cell; this may be a component of the secretory Ca flux. Kinetic considerations make a significant Ca movement via the ER-Golgi endomembrane space less likely. The mitochondrial Ca concentration is low, and not significantly changed by cholinergic stimulation. X-ray microanalysis was carried out on submandibular glands of rats after chronic treatment with reserpin and/or isoproterenol (an animal model for cystic fibrosis, CF). The acinar cells had elevated Mg and Ca and lowered K concentrations. Analysis of ultrathin cryosections showed high levels of Ca and Mg in secretory granules, mucus globules and the ER. Ca and Mg in the ER may be transported intracellularly with secretory proteins to secretion granules or mucus globules. The decrease in cell K may be due to efflux of K caused by elevated cytoplasmic Ca levels. A similar decrease in cell K was caused by incubation of rat salivary glands with diluted serum from CF patients, a treatment which has been reported to mimic the effect of a rise in cytoplasmic Ca.

  5. Chelatometric determination of calcium and magnesium in iron ores, slags, anorthosite, limestone, copper-nickel-lead-zinc ores and divers materials.

    PubMed

    Hitchen, A; Zechanowitsch, G

    1980-03-01

    Chelatometric methods for the determination of calcium and magnesium in iron ores, slags, anorthosite, copper-nickel-lead-zinc ores and various other materials are described. Potential interfering elements are masked with triethanolamine and potassium cyanide. In one aliquot calcium is titrated at pH > 12, with calcein and thymolphthalein mixed indicator and in another aliquot calcium and magnesium are titrated in ammonia buffer, with o-cresolphthalein complexone screened with Naphthol Green B as indicator. The results compare favourably with certified values for reference materials of diverse nature. PMID:18962661

  6. Measurement and calculation of the Stark-broadening parameters for the resonance lines of singly ionized calcium and magnesium.

    NASA Technical Reports Server (NTRS)

    Jones, W. W.; Sanchez, A.; Greig, J. R.; Griem, H. R.

    1972-01-01

    The electron-impact-broadened profiles of the resonance lines of singly ionized calcium and magnesium have been measured using an electromagnetically driven shock tube and a rapid-scanning Fabry-Perot spectrometer. For an electron density of 10 to the 17th power per cu cm and a temperature of 19,000 K, we found the Lorentzian half-width of the Ca+ line to be 0.086 A plus or minus 10% and of the Mg+ line to be 0.044 A plus or minus 10%. Using the quantum-mechanical theory of Barnes and Peach and our semiclassical calculation for the calcium lines, we found that the temperature dependence of the theoretical curves is close to that measured, although both theories predict actual values which are somewhat large.

  7. TRPM7 is involved in angiotensin II induced cardiac fibrosis development by mediating calcium and magnesium influx.

    PubMed

    Yu, Yang; Chen, Shaorui; Xiao, Chuyao; Jia, Yanyan; Guo, Jinlei; Jiang, Jianmin; Liu, Peiqing

    2014-05-01

    Cardiac fibrosis is involved in a lot of cardiovascular pathological processes. Cardiac fibrosis can block conduction, cause hypoxia, strengthen myocardial stiffness, create electrical heterogeneity, and hamper systolic ejection, which is associated with the development of arrhythmia, heart failure and sudden cardiac death. Besides the initial stimulating factors, the cardiac fibroblasts (CFs) are the principal responsible cells in the fibrogenesis cascade of events. TRPM7, a member of the TRPM (Melastatin) subfamily, is a non-selective cation channel, which permeates both Ca(2+) and Mg(2+). Here we demonstrated TRPM7 expression in CFs, and 2-APB (TRPM7 inhibitor), inhibited Ang II-induced CTGF, α-SMA expression and CFs proliferation. Besides, knocking down TRPM7 by shRNA, we proved that TRPM7 mediated both calcium and magnesium changes in cardiac fibroblasts which contribute to fibrosis progress. This study suggested that TRPM7 should play a pivotal role in cardiac fibroblast functions associated to cardiac fibrosis development. PMID:24680379

  8. Changes in Sodium, Calcium, and Magnesium Ion Concentrations That Inhibit Geobacillus Biofilms Have No Effect on Anoxybacillus flavithermus Biofilms

    PubMed Central

    Somerton, B.; Lindsay, D.; Palmer, J.; Brooks, J.

    2015-01-01

    This study investigated the effects of varied sodium, calcium, and magnesium concentrations in specialty milk formulations on biofilm formation by Geobacillus spp. and Anoxybacillus flavithermus. The numbers of attached viable cells (log CFU per square centimeter) after 6 to 18 h of biofilm formation by three dairy-derived strains of Geobacillus and three dairy-derived strains of A. flavithermus were compared in two commercial milk formulations. Milk formulation B had relatively high sodium and low calcium and magnesium concentrations compared with those of milk formulation A, but the two formulations had comparable fat, protein, and lactose concentrations. Biofilm formation by the three Geobacillus isolates was up to 4 log CFU cm−2 lower in milk formulation B than in milk formulation A after 6 to 18 h, and the difference was often significant (P ≤ 0.05). However, no significant differences (P ≤ 0.05) were found when biofilm formations by the three A. flavithermus isolates were compared in milk formulations A and B. Supplementation of milk formulation A with 100 mM NaCl significantly decreased (P ≤ 0.05) Geobacillus biofilm formation after 6 to 10 h. Furthermore, supplementation of milk formulation B with 2 mM CaCl2 or 2 mM MgCl2 significantly increased (P ≤ 0.05) Geobacillus biofilm formation after 10 to 18 h. It was concluded that relatively high free Na+ and low free Ca2+ and Mg2+ concentrations in milk formulations are collectively required to inhibit biofilm formation by Geobacillus spp., whereas biofilm formation by A. flavithermus is not impacted by typical cation concentration differences of milk formulations. PMID:26002898

  9. Calcium and magnesium disorders.

    PubMed

    Goff, Jesse P

    2014-07-01

    Hypocalcemia is a clinical disorder that can be life threatening to the cow (milk fever) and predisposes the animal to various other metabolic and infectious disorders. Calcium homeostasis is mediated primarily by parathyroid hormone, which stimulates bone calcium resorption and renal calcium reabsorption. Parathyroid hormone stimulates the production of 1,25-dihydroxyvitamin D to enhance diet calcium absorption. High dietary cation-anion difference interferes with tissue sensitivity to parathyroid hormone. Hypomagnesemia reduces tissue response to parathyroid hormone. PMID:24980727

  10. Short term spatio-temporal variability of soil water-extractable calcium and magnesium after a low severity grassland fire in Lithuania.

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Martin, David

    2014-05-01

    Fire has important impacts on soil nutrient spatio-temporal distribution (Outeiro et al., 2008). This impact depends on fire severity, topography of the burned area, type of soil and vegetation affected, and the meteorological conditions post-fire. Fire produces a complex mosaic of impacts in soil that can be extremely variable at small plot scale in the space and time. In order to assess and map such a heterogeneous distribution, the test of interpolation methods is fundamental to identify the best estimator and to have a better understanding of soil nutrients spatial distribution. The objective of this work is to identify the short-term spatial variability of water-extractable calcium and magnesium after a low severity grassland fire. The studied area is located near Vilnius (Lithuania) at 54° 42' N, 25° 08 E, 158 masl. Four days after the fire, it was designed in a burned area a plot with 400 m2 (20 x 20 m with 5 m space between sampling points). Twenty five samples from top soil (0-5 cm) were collected immediately after the fire (IAF), 2, 5, 7 and 9 months after the fire (a total of 125 in all sampling dates). The original data of water-extractable calcium and magnesium did not respected the Gaussian distribution, thus a neperian logarithm (ln) was applied in order to normalize data. Significant differences of water-extractable calcium and magnesium among sampling dates were carried out with the Anova One-way test using the ln data. In order to assess the spatial variability of water-extractable calcium and magnesium, we tested several interpolation methods as Ordinary Kriging (OK), Inverse Distance to a Weight (IDW) with the power of 1, 2, 3 and 4, Radial Basis Functions (RBF) - Inverse Multiquadratic (IMT), Multilog (MTG), Multiquadratic (MTQ) Natural Cubic Spline (NCS) and Thin Plate Spline (TPS) - and Local Polynomial (LP) with the power of 1 and 2. Interpolation tests were carried out with Ln data. The best interpolation method was assessed using the

  11. The functional unit of calcium-plus-magnesium-ion-dependent adenosine triphosphatase from sarcoplasmic reticulum. The aggregational state of the deoxycholate-solubilized protein in an enzymically active form

    PubMed Central

    Jørgensen, Karl E.; Lind, Kirsten E.; Røigaard-Petersen, Hans; Møller, Jesper V.

    1978-01-01

    Vesicles consisting of (Ca2++Mg2+)-dependent ATPase (adenosine triphosphatase), and lipid were prepared from sarcoplasmic reticulum of rabbit skeletal muscle. As with non-ionic detergents [le Maire, Møller & Tanford (1976) Biochemistry 15, 2336–2342] the (Ca2++Mg2+)-dependent ATPase after solubilization by deoxycholate showed a pronounced tendency to form oligomers in gel-chromatographic experiments, when eluted in the presence of deoxycholate and phosphatidylcholine. To evaluate the functional significance of oligomer formation the properties of enzymically active preparations of ATPase, solubilized by deoxycholate, were studied. Such preparations were obtained at a protein concentration of 2.5mg/ml in the presence of a high salt concentration (0.4m-KCl) and sucrose (0.3m) in the solubilization medium. Analytical ultracentrifugation of solubilized ATPase showed one protein boundary moving at the same rate as gel-chromatographically prepared monomeric ATPase (s20,w=6.0S). From simultaneous measurements of the diffusion coefficient an apparent molecular weight of 133000 was calculated, consistent with solubilization of ATPase in predominantly monomeric form. The enzymic activity of deoxycholate-solubilized ATPase when measured directly in the solubilization medium at optimal Ca2+ and MgATP concentrations was about 35–50% of that of vesicular ATPase. The dependence of enzymic activity on MgATP concentration indicated that the solubilized ATPase retained high-affinity binding of MgATP, but the presence of high concentrations of the nucleotide did not stimulate activity further, in contrast with that of vesicular ATPase. The dependence of enzymic activity on the free Ca2+ concentration was essentially the same for both solubilized and vesicular forms, indicating that interaction of ATPase with more than one molecule of Ca2+ is required for enzyme activity. Solubilized enzyme at 20°C was phosphorylated to about the same degree as vesicular ATPase. It is concluded

  12. DETERMINATION OF MATERNAL SERUM ZINC, IRON, CALCIUM AND MAGNESIUM DURING PREGNANCY IN PREGNANT WOMEN AND UMBILICAL CORD BLOOD AND THEIR ASSOCIATION WITH OUTCOME OF PREGNANCY

    PubMed Central

    Khoushabi, Fahimeh; Shadan, Mohammad Reza; Miri, Ali; Sharifi-Rad, Javad

    2016-01-01

    Background: Trace elements and specially minerals are critical for the development of fetus. Many minerals are transferred to the fetus for fetal stores in the latter part of the pregnancy. It has been shown that various trace elements such as Zinc, Iron, Calcium and Magnesium are metabolically interrelated and there is alteration in their concentration during pregnancy. Beyond pregnancy is associated with increased demand of all the nutrients and deficiency of any of these could affect pregnancy, delivery and outcome of pregnancy. Aim: To study the levels of trace elements namely zinc, iron, magnesium and calcium in maternal and umbilical cord blood and their association with pregnancy outcome. Methods: Sixty pregnant women in Zabol, Iran were selected from those who had registered their names for the prenatal care and who had followed up till the 3rd trimester of pregnancy ending in child birth. Biochemical parameters analyzed with help of the biochemical laboratory. Data were analyzed by SPSS software. Results: The mean biochemical profile such, serum calcium, magnesium, zinc and iron in the pregnant women were as follow: in the 1st trimester 8.3, 1.9, 74.9 and 74.4 µg/dl respectively; in the 2nd trimester 8.5, 1.9, 73.1 and 79.3 µg/dl, respectively; in the 3rd trimester 8.6, 1.9, 68.4, and 82.2 µg/dl, respectively. In the umbilical cord blood, the mean serum calcium, magnesium, zinc and iron were 8.5, 1.9, 84.1, and 89.8 µg/dl, respectively. The mean serum calcium and magnesium during the three trimesters of pregnancy were not significantly different from that in the umbilical cord blood, while the mean serum zinc and iron in the umbilical cord blood were significantly different (p<0.05) in the three trimester of pregnancy. The mean birth weight of neonates was 3.1 kg and 12% of neonates showed low birth weight. Our findings showed that, except magnesium, the profile of other biochemical variables, namely, calcium, zinc and iron in the umbilical cord blood

  13. Proliferation of Rous sarcoma virus-infected, but not of normal, chicken fibroblasts in a medium of reduced calcium and magnesium concentration

    PubMed Central

    Balk, Samuel D.; Polimeni, Philip I.; Hoon, Baldev Singh; LeStourgeon, Dana N.; Mitchell, Richard S.

    1979-01-01

    Both normal and Rous sarcoma virus-infected chicken fibroblasts proliferate actively in a culture medium containing physiological concentrations of calcium (1.2 mM) and magnesium (0.7 mM). In the presence of a physiological concentration of magnesium, reduction of the calcium concentration to 0.125 mM resulted in a significant decrease in the proliferation of the normal, but not of the neoplastic, fibroblasts. Reduction of the magnesium concentration to 0.05 mM in the presence of a physiological concentration of calcium had a similar effect. In a culture medium containing reduced concentrations of both calcium (0.20 mM) and magnesium (0.05 mM), the normal fibroblasts were maintained without proliferation, whereas the Rous sarcoma virus-infected fibroblasts continued to proliferate actively. The cytosol concentrations of ionized calcium and magnesium are known to be regulated by a balance between net passive influx and active extrusion and sequestration. On the basis of this consideration and the findings described above it can be hypothesized that: (i) Fibroblast replication is initiated when cytosolic concentrations of calcium, magnesium, or both rise above a critical level. (ii) Autonomous initiation of replication of neoplastic fibroblasts is a result of failure of cytoplasmic divalent cation homeostasis; alternatively, sarcoma virus infection may endow cells with a divalent cation-independent mechanism that bypasses an initiation mechanism that is, normally, divalent cation-dependent. (iii) Proliferation of normal fibroblasts is controlled by extracellular matrix components that interact with cell surfaces in a manner that limits the permeability of plasma membranes to divalent cations or otherwise functions to lower cytosol divalent cation concentrations. PMID:226989

  14. The effects of secular calcium and magnesium concentration changes on the thermodynamics of seawater acid/base chemistry: Implications for Eocene and Cretaceous ocean carbon chemistry and buffering

    NASA Astrophysics Data System (ADS)

    Hain, Mathis P.; Sigman, Daniel M.; Higgins, John A.; Haug, Gerald H.

    2015-05-01

    Reconstructed changes in seawater calcium and magnesium concentration ([Ca2+], [Mg2+]) predictably affect the ocean's acid/base and carbon chemistry. Yet inaccurate formulations of chemical equilibrium "constants" are currently in use to account for these changes. Here we develop an efficient implementation of the MIAMI Ionic Interaction Model to predict all chemical equilibrium constants required for carbon chemistry calculations under variable [Ca2+] and [Mg2+]. We investigate the impact of [Ca2+] and [Mg2+] on the relationships among the ocean's pH, CO2, dissolved inorganic carbon (DIC), saturation state of CaCO3 (Ω), and buffer capacity. Increasing [Ca2+] and/or [Mg2+] enhances "ion pairing," which increases seawater buffering by increasing the concentration ratio of total to "free" (uncomplexed) carbonate ion. An increase in [Ca2+], however, also causes a decline in carbonate ion to maintain a given Ω, thereby overwhelming the ion pairing effect and decreasing seawater buffering. Given the reconstructions of Eocene [Ca2+] and [Mg2+] ([Ca2+]~20 mM; [Mg2+]~30 mM), Eocene seawater would have required essentially the same DIC as today to simultaneously explain a similar-to-modern Ω and the estimated Eocene atmospheric CO2 of ~1000 ppm. During the Cretaceous, at ~4 times modern [Ca2+], ocean buffering would have been at a minimum. Overall, during times of high seawater [Ca2+], CaCO3 saturation, pH, and atmospheric CO2 were more susceptible to perturbations of the global carbon cycle. For example, given both Eocene and Cretaceous seawater [Ca2+] and [Mg2+], a doubling of atmospheric CO2 would require less carbon addition to the ocean/atmosphere system than under modern seawater composition. Moreover, increasing seawater buffering since the Cretaceous may have been a driver of evolution by raising energetic demands of biologically controlled calcification and CO2 concentration mechanisms that aid photosynthesis.

  15. Multiparametric Flow System for the Automated Determination of Sodium, Potassium, Calcium, and Magnesium in Large-Volume Parenteral Solutions and Concentrated Hemodialysis Solutions

    PubMed Central

    Pistón, Mariela; Dol, Isabel

    2006-01-01

    A multiparametric flow system based on multicommutation and binary sampling has been designed for the automated determination of sodium, potassium, calcium, and magnesium in large-volume parenteral solutions and hemodialysis concentrated solutions. The goal was to obtain a computer-controlled system capable of determining the four metals without extensive modifications. The system involved the use of five solenoid valves under software control, allowing the establishment of the appropriate flow conditions for each analyte, that is, sample size, dilution, reagent addition, and so forth. Detection was carried out by either flame atomic emission spectrometry (sodium, potassium) or flame atomic absorption spectrometry (calcium, magnesium). The influence of several operating parameters was studied. Validation was carried out by analyzing artificial samples. Figures of merit obtained include linearity, accuracy, precision, and sampling frequency. Linearity was satisfactory: sodium, r 2 >0.999 ( 0.5 – 3.5 g/L), potassium, r 2 >0.996 (50–150 mg/L), calcium, r 2 >0.999 (30–120 mg/L), and magnesium, r 2 >0.999 (20–40 mg/L). Precision ( s r , %, n=5 ) was better than 2.1 %, and accuracy (evaluated through recovery assays) was in the range of 99.8 %– 101.0 % (sodium), 100.8 – 102.5 % (potassium), 97.3 %– 101.3 % (calcium), and 97.1 %– 99.8 % (magnesium). Sampling frequencies ( h −1 ) were 70 (sodium), 75 (potassium), 70 (calcium), and 58 (magnesium). According to the results obtained, the use of an automated multiparametric system based on multicommutation offers several advantages for the quality control of large-volume parenteral solutions and hemodialysis concentrated solutions. PMID:17671619

  16. Adenosine transporters.

    PubMed

    Thorn, J A; Jarvis, S M

    1996-06-01

    1. In mammals, nucleoside transport is an important determinant of the pharmacokinetics, plasma and tissue concentration, disposition and in vivo biological activity of adenosine as well as nucleoside analogues used in antiviral and anticancer therapies. 2. Two broad types of adenosine transporter exist, facilitated-diffusion carriers and active processes driven by the transmembrane sodium gradient. 3. Facilitated-diffusion adenosine carriers may be sensitive (es) or insensitive (ei) to nanomolar concentrations of the transport inhibitor nitrobenzylthioinosine (NBMPR). Dipyridamole, dilazep and lidoflazine analogues are also more potent inhibitors of the es carrier than the ei transporter in cells other than those derived from rat tissues. 4. The es transporter has a broad substrate specificity (apparent Km for adenosine approximately 25 microM in many cells at 25 degrees C), is a glycoprotein with an average apparent Mr of 57,000 in human erythrocytes that has been purified to near homogeneity and may exist in situ as a dimer. However, there is increasing evidence to suggest the presence of isoforms of the es transporter in different cells and species, based on kinetic and molecular properties. 5. The ei transporter also has a broad substrate specificity with a lower affinity for some nucleoside permeants than the es carrier, is genetically distinct from es but little information exists as to the molecular properties of the protein. 6. Sodium-dependent adenosine transport is present in many cell types and catalysed by four distinct systems, N1-N4, distinguished by substrate specificity, sodium coupling and tissue distribution. 7. Two genes have been identified which encode sodium-dependent adenosine transport proteins, SNST1 from the sodium/glucose cotransporter (SGLT1) gene family and the rat intestinal N2 transporter (cNT1) from a novel gene family including a bacterial nucleoside carrier (NupC). Transcripts of cNT1, which encodes a 648-residue protein, are

  17. Abnormalities of serum calcium and magnesium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neonatal hypocalcemia is defined as a total serum calcium concentration of <7 mg/dL or an ionized calcium concentration of <4 mg/dL (1mmol/L). In very low birth weight (VLBW) infants, ionized calcium values of 0.8 to 1 mmol/L are common and not usually associated with clinical symptoms. In larger in...

  18. Adenosine and Ischemic Preconditioning

    PubMed Central

    Liang, Bruce T.; Swierkosz, Tomasz A.; Herrmann, Howard C.; Kimmel, Stephen; Jacobson, Kenneth A.

    2012-01-01

    Adenosine is released in large amounts during myocardial ischemia and is capable of exerting potent cardioprotective effects in the heart. Although these observations on adenosine have been known for a long time, how adenosine acts to achieve its anti-ischemic effect remains incompletely understood. However, recent advances on the chemistry and pharmacology of adenosine receptor ligands have provided important and novel information on the function of adenosine receptor subtypes in the cardiovascular system. The development of model systems for the cardiac actions of adenosine has yielded important insights into its mechanism of action and have begun to elucidate the sequence of signalling events from receptor activation to the actual exertion of its cardioprotective effect. The present review will focus on the adenosine receptors that mediate the potent anti-ischemic effect of adenosine, new ligands at the receptors, potential molecular signalling mechanisms downstream of the receptor, mediators for cardioprotection, and possible clinical applications in cardiovascular disorders. PMID:10607860

  19. Adenosine and Bone Metabolism

    PubMed Central

    Mediero, Aránzazu; Cronstein, Bruce N.

    2013-01-01

    Bone is a dynamic organ that undergoes continuous remodeling whilst maintaining a balance between bone formation and resorption. Osteoblasts, which synthesize and mineralize new bone, and osteoclasts, the cells that resorb bone, act in concert to maintain bone homeostasis. In recent years, there has been increasing appreciation of purinergic regulation of bone metabolism. Adenosine, released locally, mediates its physiologic and pharmacologic actions via interactions with G-protein coupled receptors and recent work has indicated that these receptors are involved in the regulation of osteoclast differentiation and function, as well as osteoblast differentiation and bone formation. Moreover, adenosine receptors also regulate chondrocyte and cartilage homeostasis. These recent findings underscore the potential therapeutic importance of adenosine receptors in regulating bone physiology and pathology. PMID:23499155

  20. Adenosine receptor interactions and anxiolytics.

    PubMed

    Bruns, R F; Katims, J J; Annau, Z; Snyder, S H; Daly, J W

    1983-12-01

    [3H]-N6-cyclohexyladenosine and [3H]-1,3-diethyl-8-phenylxanthine label the A1 subtype of adenosine receptor in brain membranes. The affinities of methylxanthines in competing for A1 adenosine receptors parallel their potencies as locomotor stimulants. The adenosine agonist N6-(phenylisopropyl) adenosine is a potent locomotor depressant. Both diazepam and N6-(L-phenylisopropyl)adenosine cause locomotor stimulation in a narrow range of subdepressant doses. Combined stimulant doses of the two agents depress motor activity, as do larger doses of either one, given separately. Evidence supporting and against the hypothesis that some of the actions of benzodiazepines are mediated via the adenosine system is reviewed. A number of compounds interact with both systems, probably because of physico-chemical similarities between adenosine and diazepam. It is concluded that of the four classic actions of benzodiazepines, the sedative and muscle relaxant (but not anxiolytic or anticonvulsant) actions could possibly be mediated by adenosine. PMID:6199685

  1. Adenosine in fibrosis

    PubMed Central

    Chan, Edwin S. L.

    2011-01-01

    Adenosine is an endogenous autocoid that regulates a multitude of bodily functions. Its anti-inflammatory actions are well known to rheumatologists since it mediates many of the anti-inflammatory effects of a number of antirheumatic drugs such as methotrexate. However, inflammatory and tissue regenerative responses are intricately linked, with wound healing being a prime example. It has only recently been appreciated that adenosine has a key role in tissue regenerative and fibrotic processes. An understanding of these processes may shed new light on potential therapeutic options in diseases such as scleroderma where tissue fibrosis features prominently. PMID:19949965

  2. Adenosine and sleep

    SciTech Connect

    Yanik, G.M. Jr.

    1987-01-01

    Behavioral and biochemical approaches have been used to determine the relative contribution of endogenous adenosine and adenosine receptors to the sleep-wake cycle in the rat. Adenosine concentrations in specific areas of the rat brain were not affected by 24 hours of total sleep deprivation, or by 24 or 48 hours of REM sleep deprivation. In order to assess the effect of REM sleep deprivation on adenosine A/sub 1/ receptors, /sup 3/H-L-PIA binding was measured. The Bmax values for /sup 3/H-L-PIA binding to membrane preparations of the cortices and corpus striata from 48 hour REM sleep-deprived animals were increased 14.8% and 23%, respectively. These increases were not maintained following the cessation of sleep deprivation and recovered within 2 hours. The results of a 96 hour REM deprivation experiment were similar to those of the 48 hour REM sleep deprivation experiment. However, these increases were not evident in similar structures taken from stress control animals, and conclusively demonstrated that the changes in /sup 3/H-L-PIA binding resulted from REM sleep deprivation and not from stress.

  3. Adenosine kinase inhibitors attenuate opiate withdrawal via adenosine receptor activation.

    PubMed

    Kaplan, G B; Coyle, T S

    1998-11-27

    Previous studies have demonstrated a role for adenosine in mediating opiate effects. This study examines the effects of indirect activation of adenosine receptors, via treatment with adenosine kinase inhibitors, on the expression of opiate withdrawal in mice. Mice receive chronic morphine treatment via implantation of subcutaneous morphine pellets (75 mg) for 72 h. Mice then receive parenteral treatment with adenosine kinase inhibitors, either 5'-amino-5'-deoxyadenosine (2, 5, 20, 40 mg/kg, intraperitoneal or i.p.) or iodotubericidin (1, 2, 5 mg/kg, i.p.), followed by naloxone injection and opiate withdrawal signs are measured over 20 min. Both adenosine kinase inhibitors significantly reduce the following opiate withdrawal signs in a dose-dependent manner compared to vehicle: withdrawal jumps, teeth chattering, forepaw tremors, and forepaw treads. Additionally, 5'-amino-5'-deoxyadenosine significantly reduces withdrawal-induced diarrhea and weight loss. Effects of 5'-amino-5'-deoxyadenosine (40 mg/kg) on opiate withdrawal signs appear to be mediated via adenosine receptor activation as they are reversed by pretreatment by adenosine receptor antagonist caffeine (20 mg, i.p.) but not by selective phosphodiesterase inhibitor Ro 20-1724 (10 mg/kg, i.p.). Adenosine receptor activation via adenosine kinase inhibitor treatment attenuates opiate withdrawal and these agents may be generally useful in the treatment of drug withdrawal syndromes. PMID:9865523

  4. Adenosine receptor desensitization and trafficking.

    PubMed

    Mundell, Stuart; Kelly, Eamonn

    2011-05-01

    As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field. PMID:20550943

  5. Genetics Home Reference: adenosine deaminase 2 deficiency

    MedlinePlus

    ... Health Conditions adenosine deaminase 2 deficiency adenosine deaminase 2 deficiency Enable Javascript to view the expand/collapse ... PDF Open All Close All Description Adenosine deaminase 2 (ADA2) deficiency is a disorder characterized by abnormal ...

  6. Metal Ion Dependence of Cooperative Collapse Transitions in RNA

    SciTech Connect

    Moghaddam, Sarvin; Caliskan, Gokhan; Chauhan, Seema; Hyeon, Changbong; Briber, R.M.; Thirumalai, D.; Woodson, Sarah A.

    2010-10-12

    Positively charged counterions drive RNA molecules into compact configurations that lead to their biologically active structures. To understand how the valence and size of the cations influences the collapse transition in RNA, small-angle X-ray scattering was used to follow the decrease in the radius of gyration (R{sub g}) of the Azoarcus and Tetrahymena ribozymes in different cations. Small, multivalent cations induced the collapse of both ribozymes more efficiently than did monovalent ions. Thus, the cooperativity of the collapse transition depends on the counterion charge density. Singular value decomposition of the scattering curves showed that folding of the smaller and more thermostable Azoarcus ribozyme is well described by two components, whereas collapse of the larger Tetrahymena ribozyme involves at least one intermediate. The ion-dependent persistence length, extracted from the distance distribution of the scattering vectors, shows that the Azoarcus ribozyme is less flexible at the midpoint of transition in low-charge-density ions than in high-charge-density ions. We conclude that the formation of sequence-specific tertiary interactions in the Azoarcus ribozyme overlaps with neutralization of the phosphate charge, while tertiary folding of the Tetrahymena ribozyme requires additional counterions. Thus, the stability of the RNA structure determines its sensitivity to the valence and size of the counterions.

  7. [Adenosine and its role in physiology].

    PubMed

    Novotný, J

    2015-01-01

    Adenosine is not just a major component of adenine nucleotides and ribonucleic acids, but also has its own signaling functions. ExtraceIlular level of adenosine in an organism is strictly maintained through the balance between its formation, degradation and transport. Adenosine is formed by enzymatic degradation of adenosine triphosphate and eliminated by phosphorylation to adenosine monophosphate or by deamination to inosine. Transport of adenosine across the cell membrane is ensured by equilibrative and concentrative nucleoside transporters. All these processes participate in maintenance of adenosine level under normal conditions, but a balanced equilibrium can be disrupted in some pathophysiological situations. Extracellular adenosine as a signaling molecule binds to adenosine receptors, which may trigger via their cognate trimeric G proteins different signaling pathways. In this way, adenosine regulates energy homeostasis and affects the function of various organs. Targeted pharmacological manipulations of specific adenosine receptor subtypes or enzymes involved in its metabolism can potentially be used for therapeutic purposes. PMID:26738245

  8. Spectrophotometric Titration of a Mixture of Calcium and Magnesium.

    ERIC Educational Resources Information Center

    Fulton, Robert; And Others

    1986-01-01

    Describes a spectrophotometric titration experiment which uses a manual titration spectrophotometer and manually operated buret, rather than special instrumentation. Identifies the equipment, materials, and procedures needed for the completion of the experiment. Recommends the use of this experiment in introductory quantitative analysis…

  9. Tropical Andean forest derives calcium and magnesium from Saharan dust

    NASA Astrophysics Data System (ADS)

    Boy, Jens; Wilcke, Wolfgang

    2008-03-01

    We quantified base metal deposition to Amazonian montane rain forest in Ecuador between May 1998 and April 2003 and assessed the response of the base metal budget of three forested microcatchments (8-13 ha). There was a strong interannual variation in deposition of Ca [4.4-29 kg ha-1 a-1], Mg [1.6-12], and K [9.8-30]). High deposition changed the Ca and Mg budgets of the catchments from loss to retention, suggesting that the additionally available Ca and Mg was used by the ecosystem. Increased base metal deposition was related to dust outbursts of the Sahara and an Amazonian precipitation pattern with trans-regional dry spells allowing for dust transport to the Andes. The increased base metal deposition coincided with a strong La Niña event in 1999/2000.

  10. Health Significance of Calcium and Magnesium: Examples from Human Studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is clear that many people do not consume recommended intakes of calcium (Ca) and magnesium (Mg), yet biochemical and/or functional changes indicative of deficiencies in these nutrients have been rare. This prompted two series of studies: one addressing an apparent Ca-deficiency rickets in child...

  11. Purine metabolism in adenosine deaminase deficiency.

    PubMed Central

    Mills, G C; Schmalstieg, F C; Trimmer, K B; Goldman, A S; Goldblum, R M

    1976-01-01

    Purine and pyrimidine metabolites were measured in erythrocytes, plasma, and urine of a 5-month-old infant with adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) deficiency. Adenosine and adenine were measured using newly devised ion exchange separation techniques and a sensitive fluorescence assay. Plasma adenosine levels were increased, whereas adenosine was normal in erythrocytes and not detectable in urine. Increased amounts of adenine were found in erythrocytes and urine as well as in the plasma. Erythrocyte adenosine 5'-monophosphate and adenosine diphosphate concentrations were normal, but adenosine triphosphate content was greatly elevated. Because of the possibility of pyrimidine starvation, pyrimidine nucleotides (pyrimidine coenzymes) in erythrocytes and orotic acid in urine were measured. Pyrimidine nucleotide concentrations were normal, while orotic acid was not detected. These studies suggest that the immune deficiency associated with adenosine deaminase deficiency may be related to increased amounts of adenine, adenosine, or adenine nucleotides. PMID:1066699

  12. Adenosine-Associated Delivery Systems

    PubMed Central

    Kazemzadeh-Narbat, Mehdi; Annabi, Nasim; Tamayol, Ali; Oklu, Rahmi; Ghanem, Amyl; Khademhosseini, Ali

    2016-01-01

    Adenosine is a naturally occurring purine nucleoside in every cell. Many critical treatments such as modulating irregular heartbeat (arrhythmias), regulation of central nervous system (CNS) activity, and inhibiting seizural episodes can be carried out using adenosine. Despite the significant potential therapeutic impact of adenosine and its derivatives, the severe side effects caused by their systemic administration have significantly limited their clinical use. In addition, due to adenosine’s extremely short half-life in human blood (less than 10 s), there is an unmet need for sustained delivery systems to enhance efficacy and reduce side effects. In this paper, various adenosine delivery techniques, including encapsulation into biodegradable polymers, cell-based delivery, implantable biomaterials, and mechanical-based delivery systems, are critically reviewed and the existing challenges are highlighted. PMID:26453156

  13. Extracellular guanosine regulates extracellular adenosine levels

    PubMed Central

    Cheng, Dongmei; Jackson, Travis C.; Verrier, Jonathan D.; Gillespie, Delbert G.

    2013-01-01

    The aim of this investigation was to test the hypothesis that extracellular guanosine regulates extracellular adenosine levels. Rat preglomerular vascular smooth muscle cells were incubated with adenosine, guanosine, or both. Guanosine (30 μmol/l) per se had little effect on extracellular adenosine levels. Extracellular adenosine levels 1 h after addition of adenosine (3 μmol/l) were 0.125 ± 0.020 μmol/l, indicating rapid disposition of extracellular adenosine. Extracellular adenosine levels 1 h after addition of adenosine (3 μmol/l) plus guanosine (30 μmol/l) were 1.173 ± 0.061 μmol/l, indicating slow disposition of extracellular adenosine. Cell injury increased extracellular levels of endogenous adenosine and guanosine, and the effects of cell injury on endogenous extracellular adenosine were modulated by altering the levels of endogenous extracellular guanosine with exogenous purine nucleoside phosphorylase (converts guanosine to guanine) or 8-aminoguanosine (inhibits purine nucleoside phosphorylase). Extracellular guanosine also slowed the disposition of extracellular adenosine in rat preglomerular vascular endothelial cells, mesangial cells, cardiac fibroblasts, and kidney epithelial cells and in human aortic and coronary artery vascular smooth muscle cells and coronary artery endothelial cells. The effects of guanosine on adenosine levels were not mimicked or attenuated by 5-iodotubericidin (adenosine kinase inhibitor), erythro-9-(2-hydroxy-3-nonyl)-adenine (adenosine deaminase inhibitor), 5-aminoimidazole-4-carboxamide (guanine deaminase inhibitor), aristeromycin (S-adenosylhomocysteine hydrolase inhibitor), low sodium (inhibits concentrative nucleoside transporters), S-(4-nitrobenzyl)−6-thioinosine [inhibits equilibrative nucleoside transporter (ENT) type 1], zidovudine (inhibits ENT type 2), or acadesine (known modulator of adenosine levels). Guanosine also increases extracellular inosine, uridine, thymidine, and cytidine, yet decreases

  14. Genetics Home Reference: adenosine monophosphate deaminase deficiency

    MedlinePlus

    Skip to main content Your Guide to Understanding Genetic Conditions Enable Javascript for addthis links to activate. ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions adenosine monophosphate deaminase deficiency adenosine ...

  15. Adenosine Receptors and Membrane Microdomains

    PubMed Central

    Lasley, Robert D.

    2010-01-01

    Adenosine receptors are a member of the large family of seven transmembrane spanning G protein coupled receptors (GPCR). The four adenosine receptor subtypes – A1, A2a, A2b, A3 – exert their effects via the activation of one or more heterotrimeric G proteins resulting in the modulation of intracellular signaling. Numerous studies over the past decade have documented the complexity of GPCR signaling at the level of protein-protein interactions as well as through signaling crosstalk. With respect to adenosine receptors the activation of one receptor subtype can have profound direct effects in one cell type, but little or no effect in other cells. There is significant evidence that the compartmentation of subcellular signaling plays a physiological role in the fidelity of GPCR signaling. This compartmentation is evident at the level of the plasma membrane in the form of membrane microdomains such as caveolae and lipid rafts. This review will summarize and critically assess our current understanding of the role of membrane microdomains in regulating adenosine receptor signaling. PMID:20888790

  16. Xanthines as Adenosine Receptor Antagonists

    PubMed Central

    Jacobson, Kenneth A.

    2013-01-01

    The natural plant alkaloids caffeine and theophylline were the first adenosine receptor (AR) antagonists described in the literature. They exhibit micromolar affinities and are non-selective. A large number of derivatives and analogs have subsequently been synthesized and evaluated as AR antagonists. Very potent antagonists have thus been developed with selectivity for each of the four AR subtypes. PMID:20859796

  17. Regulation of adenosine levels during cerebral ischemia

    PubMed Central

    Chu, Stephanie; Xiong, Wei; Zhang, Dali; Soylu, Hanifi; Sun, Chao; Albensi, Benedict C; Parkinson, Fiona E

    2013-01-01

    Adenosine is a neuromodulator with its level increasing up to 100-fold during ischemic events, and attenuates the excitotoxic neuronal injury. Adenosine is produced both intracellularly and extracellularly, and nucleoside transport proteins transfer adenosine across plasma membranes. Adenosine levels and receptor-mediated effects of adenosine are regulated by intracellular ATP consumption, cellular release of ATP, metabolism of extracellular ATP (and other adenine nucleotides), adenosine influx, adenosine efflux and adenosine metabolism. Recent studies have used genetically modified mice to investigate the relative contributions of intra- and extracellular pathways for adenosine formation. The importance of cortical or hippocampal neurons as a source or a sink of adenosine under basal and hypoxic/ischemic conditions was addressed through the use of transgenic mice expressing human equilibrative nucleoside transporter 1 (hENT1) under the control of a promoter for neuron-specific enolase. From these studies, we conclude that ATP consumption within neurons is the primary source of adenosine in neuronal cultures, but not in hippocampal slices or in vivo mice exposed to ischemic conditions. PMID:23064722

  18. Fluorescent Ligands for Adenosine Receptors

    PubMed Central

    Kozma, Eszter; Jayasekara, P Suresh; Squarcialupi, Lucia; Paoletta, Silvia; Moro, Stefano; Federico, Stephanie; Spalluto, Giampiero; Jacobson, Kenneth A.

    2012-01-01

    Interest is increasing in developing fluorescent ligands for characterization of adenosine receptors (ARs), which hold a promise of usefulness in the drug discovery process. The size of a strategically labeled AR ligand can be greatly increased after the attachment of a fluorophore. The choice of dye moiety (e.g. Alexa Fluor 488), attachment point and linker length can alter the selectivity and potency of the parent molecule. Fluorescent derivatives of adenosine agonists and antagonists (e.g. XAC and other heterocyclic antagonist scaffolds) have been synthesized and characterized pharmacologically. Some are useful AR probes for flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer, and scanning confocal microscopy. Thus, the approach of fluorescent labeled GPCR ligands, including those for ARs, is a growing dynamic research field. PMID:23200243

  19. Adenosine-induced activation of esophageal nociceptors.

    PubMed

    Ru, F; Surdenikova, L; Brozmanova, M; Kollarik, M

    2011-03-01

    Clinical studies implicate adenosine acting on esophageal nociceptive pathways in the pathogenesis of noncardiac chest pain originating from the esophagus. However, the effect of adenosine on esophageal afferent nerve subtypes is incompletely understood. We addressed the hypothesis that adenosine selectively activates esophageal nociceptors. Whole cell perforated patch-clamp recordings and single-cell RT-PCR analysis were performed on the primary afferent neurons retrogradely labeled from the esophagus in the guinea pig. Extracellular recordings were made from the isolated innervated esophagus. In patch-clamp studies, adenosine evoked activation (inward current) in a majority of putative nociceptive (capsaicin-sensitive) vagal nodose, vagal jugular, and spinal dorsal root ganglia (DRG) neurons innervating the esophagus. Single-cell RT-PCR analysis indicated that the majority of the putative nociceptive (transient receptor potential V1-positive) neurons innervating the esophagus express the adenosine receptors. The neural crest-derived (spinal DRG and vagal jugular) esophageal nociceptors expressed predominantly the adenosine A(1) receptor while the placodes-derived vagal nodose nociceptors expressed the adenosine A(1) and/or A(2A) receptors. Consistent with the studies in the cell bodies, adenosine evoked activation (overt action potential discharge) in esophageal nociceptive nerve terminals. Furthermore, the neural crest-derived jugular nociceptors were activated by the selective A(1) receptor agonist CCPA, and the placodes-derived nodose nociceptors were activated by CCPA and/or the selective adenosine A(2A) receptor CGS-21680. In contrast to esophageal nociceptors, adenosine failed to stimulate the vagal esophageal low-threshold (tension) mechanosensors. We conclude that adenosine selectively activates esophageal nociceptors. Our data indicate that the esophageal neural crest-derived nociceptors can be activated via the adenosine A(1) receptor while the placodes

  20. Pyrimidine starvation induced by adenosine in fibroblasts and lymphoid cells: role of adenosine deaminase.

    PubMed

    Green, H; Chan, T

    1973-11-23

    In the presence of 10(-4) to 10(-5) molar adenosine, established cell lines of fibroblastic or lymphoid origin die of pyrimidine starvation. Less than lethal concentrations inhibit cell growth. Over a broad concentration range, the effects of adenosine are prevented by providing a suitable pyrimidine source. We suggest that the recently described immune deficiency disease associated with absence of adenosine deaminase may be the result of pyrimidine starvation induced by adenosine nucleotides in cells of the lymphoid system. PMID:4795749

  1. Partial separation of platelet and placental adenosine receptors from adenosine A2-like binding protein

    SciTech Connect

    Zolnierowicz, S.; Work, C.; Hutchison, K.; Fox, I.H. )

    1990-04-01

    The ubiquitous adenosine A2-like binding protein obscures the binding properties of adenosine receptors assayed with 5'-N-({sup 3}H)ethylcarboxamidoadenosine (({sup 3}H)NECA). To solve this problem, we developed a rapid and simple method to separate adenosine receptors from the adenosine A2-like binding protein. Human platelet and placental membranes were solubilized with 1% 3-((3-cholamidopropyl)dimethylammonio)-1-propanesulfonate. The soluble platelet extract was precipitated with polyethylene glycol and the fraction enriched in adenosine receptors was isolated from the precipitate by differential centrifugation. The adenosine A2-like binding protein was removed from the soluble placental extract with hydroxylapatite and adenosine receptors were precipitated with polyethylene glycol. The specificity of the ({sup 3}H)NECA binding is typical of an adenosine A2 receptor for platelets and an adenosine A1 receptor for placenta. This method leads to enrichment of adenosine A2 receptors for platelets and adenosine A1 receptors for placenta. This provides a useful preparation technique for pharmacologic studies of adenosine receptors.

  2. Enzymatic regeneration of adenosine triphosphate cofactor

    NASA Technical Reports Server (NTRS)

    Marshall, D. L.

    1974-01-01

    Regenerating adenosine triphosphate (ATP) from adenosine diphosphate (ADP) by enzymatic process which utilizes carbamyl phosphate as phosphoryl donor is technique used to regenerate expensive cofactors. Process allows complex enzymatic reactions to be considered as candidates for large-scale continuous processes.

  3. Adenosine Neuromodulation and Traumatic Brain Injury

    PubMed Central

    Lusardi, T.A

    2009-01-01

    Adenosine is a ubiquitous signaling molecule, with widespread activity across all organ systems. There is evidence that adenosine regulation is a significant factor in traumatic brain injury (TBI) onset, recovery, and outcome, and a growing body of experimental work examining the therapeutic potential of adenosine neuromodulation in the treatment of TBI. In the central nervous system (CNS), adenosine (dys)regulation has been demonstrated following TBI, and correlated to several TBI pathologies, including impaired cerebral hemodynamics, anaerobic metabolism, and inflammation. In addition to acute pathologies, adenosine function has been implicated in TBI comorbidities, such as cognitive deficits, psychiatric function, and post-traumatic epilepsy. This review presents studies in TBI as well as adenosine-related mechanisms in co-morbidities of and unfavorable outcomes resulting from TBI. While the exact role of the adenosine system following TBI remains unclear, there is increasing evidence that a thorough understanding of adenosine signaling will be critical to the development of diagnostic and therapeutic tools for the treatment of TBI. PMID:20190964

  4. Effects of adenosine on intrarenal oxygenation.

    PubMed

    Dinour, D; Brezis, M

    1991-11-01

    Although generally a vasodilator, adenosine vasoconstricts cortical vessels in the kidney, reduces glomerular filtration rate (GFR), and increases medullary blood flow, effects likely to improve the medullary O2 deficiency characteristic of mammalian kidneys. To evaluate a possible role of adenosine in medullary O2 balance, we investigated the effect of adenosine upon cortical and medullary tissue PO2. Adenosine was infused into renal interstitium through chronically implanted capsules. Cortical and medullary PO2 were measured using sensitive Clark-type O2 microelectrodes inserted into kidneys of anesthetized rats at the respective depths of 1.8 and 3.7 mm. Infusion of adenosine (0.1-0.5 mumol/min) increased medullary PO2 from 17 +/- 3 (SE) to 40 +/- 5 mmHG (P less than 0.001) and decreased cortical PO2 from 64 +/- 4 to 47 +/- 3 mmHg (P less than 0.001). After the infusion was stopped, PO2 returned to baseline at both sites. Coadministration of adenosine receptor antagonist 8-phenyltheophylline (0.01 mumol/min) prevented both cortical and medullary effects of adenosine. We concluded that adenosine could play an important protective and regulatory role in renal medullary O2 balance. PMID:1951710

  5. Halobacterial adenosine triphosphatases and the adenosine triphosphatase from Halobacterium saccharovorum

    NASA Technical Reports Server (NTRS)

    Kristjansson, Hordur; Sadler, Martha H.; Hochstein, Lawrence I.

    1986-01-01

    Membranes prepared from various members of the genus Halobacterium contained a Triton X-l00 activated adenosine triphosphatase. The enzyme from Halobacterium saccharovorum was unstable in solutions of low ionic strength and maximally active in the presence of 3.5 M NaCl. A variety of nucleotide triphosphates was hydrolyzed. MgADP, the product of ATP hydrolysis, was not hydrolyzed and was a competitive inhibitor with respect to MgATP. The enzyme from H. saccharovorum was composed of at least 2 and possibly 4 subunits. The 83-kDa and 60-kDa subunits represented about 90 percent of total protein. The 60-kDa subunit reacted with dicyclohexyl-carbodiimide when inhibition was carried out in an acidic medium. The enzyme from H. saccharovorum, possesses properties of an F(1)F(0) as well as an E(1)E(2) ATPase.

  6. The partial purification of sodium-plus-potassium ion-dependent adenosine triphosphatase from the gills of Anguilla anguilla and its inhibition by orthovanadate.

    PubMed Central

    Bell, M V; Sargent, J R

    1979-01-01

    1. (Na+ +K+)-dependent ATPase was partially purified from eel gills by a procedure in which the microsomal fraction of crude preparations of chloride cells was selectively extracted with sodium dodecyl sulphate. 2. The microsomal specific activity was increased 2-fold during optimal treatment with detergent. 3. The final preparation (56% pure) had a specific activity of 341 mumol of ATP hydrolysed/h per mg of protein and a turnover number of 3560 min-1. The number of ouabain-binding sties equalled the number of sites phosphorylated by ATP. 4. Both sodium orthovanadate and ouabain inhibited the purified preparation more than the microsomal fraction, vanadate being more effective on an equimolar basis than ouabain. 5. Inhibition by orthovanadate was not enhanced at 28 mM-as compared with 1mM-MgCl2 and was not reversed by beta-adrenergic agonists (cf. Josephson & Cantley (1977) Biochemistry 16, 4572--4578). 6. Of various other metallic oxyanions tested only niobate proved an effective inhibitor of the enzyme although this anion was less effective than orthovanadate. 7. Orthovanadate partially inhibited phosphorylation of the enzyme by ATP in the presence of 28 mM-MgCl2. PMID:39542

  7. Optical Aptasensors for Adenosine Triphosphate

    PubMed Central

    Ng, Stella; Lim, Hui Si; Ma, Qian; Gao, Zhiqiang

    2016-01-01

    Nucleic acids are among the most researched and applied biomolecules. Their diverse two- and three-dimensional structures in conjunction with their robust chemistry and ease of manipulation provide a rare opportunity for sensor applications. Moreover, their high biocompatibility has seen them being used in the construction of in vivo assays. Various nucleic acid-based devices have been extensively studied as either the principal element in discrete molecule-like sensors or as the main component in the fabrication of sensing devices. The use of aptamers in sensors - aptasensors, in particular, has led to improvements in sensitivity, selectivity, and multiplexing capacity for a wide verity of analytes like proteins, nucleic acids, as well as small biomolecules such as glucose and adenosine triphosphate (ATP). This article reviews the progress in the use of aptamers as the principal component in sensors for optical detection of ATP with an emphasis on sensing mechanism, performance, and applications with some discussion on challenges and perspectives. PMID:27446501

  8. Gas-phase protonation thermochemistry of adenosine.

    PubMed

    Touboul, David; Bouchoux, Guy; Zenobi, Renato

    2008-09-18

    The goal of this work was to obtain a detailed insight on the gas-phase protonation energetic of adenosine using both mass spectrometric experiments and quantum chemical calculations. The experimental approach used the extended kinetic method with nanoelectrospray ionization and collision-induced dissociation tandem mass spectrometry. This method provides experimental values for proton affinity, PA(adenosine) = 979 +/- 1 kJ.mol (-1), and for the "protonation entropy", Delta p S degrees (adenosine) = S degrees (adenosineH +) - S degrees (adenosine) = -5 +/- 5 J.mol (-1).K (-1). The corresponding gas-phase basicity is consequently equal to: GB(adenosine) = 945 +/- 2 kJ.mol (-1) at 298K. Theoretical calculations conducted at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) level, including 298 K enthalpy correction, predict a proton affinity value of 974 kJ.mol (-1) after consideration of isodesmic proton transfer reactions with pyridine as the reference base. Moreover, computations clearly showed that N3 is the most favorable protonation site for adenosine, due to a strong internal hydrogen bond involving the hydroxyl group at the 2' position of the ribose sugar moiety, unlike observations for adenine and 2'-deoxyadenosine, where protonation occurs on N1. The existence of negligible protonation entropy is confirmed by calculations (theoretical Delta p S degrees (adenosine) approximately -2/-3 J.mol (-1).K (-1)) including conformational analysis and entropy of hindered rotations. Thus, the calculated protonation thermochemical properties are in good agreement with our experimental measurements. It may be noted that the new PA value is approximately 10 kJ.mol (-1) lower than the one reported in the National Institute of Standards and Technology (NIST) database, thus pointing to a correction of the tabulated protonation thermochemistry of adenosine. PMID:18720985

  9. Adenosine Kinase: Exploitation for Therapeutic Gain

    PubMed Central

    2013-01-01

    Adenosine kinase (ADK; EC 2.7.1.20) is an evolutionarily conserved phosphotransferase that converts the purine ribonucleoside adenosine into 5′-adenosine-monophosphate. This enzymatic reaction plays a fundamental role in determining the tone of adenosine, which fulfills essential functions as a homeostatic and metabolic regulator in all living systems. Adenosine not only activates specific signaling pathways by activation of four types of adenosine receptors but it is also a primordial metabolite and regulator of biochemical enzyme reactions that couple to bioenergetic and epigenetic functions. By regulating adenosine, ADK can thus be identified as an upstream regulator of complex homeostatic and metabolic networks. Not surprisingly, ADK dysfunction is involved in several pathologies, including diabetes, epilepsy, and cancer. Consequently, ADK emerges as a rational therapeutic target, and adenosine-regulating drugs have been tested extensively. In recent attempts to improve specificity of treatment, localized therapies have been developed to augment adenosine signaling at sites of injury or pathology; those approaches include transplantation of stem cells with deletions of ADK or the use of gene therapy vectors to downregulate ADK expression. More recently, the first human mutations in ADK have been described, and novel findings suggest an unexpected role of ADK in a wider range of pathologies. ADK-regulating strategies thus represent innovative therapeutic opportunities to reconstruct network homeostasis in a multitude of conditions. This review will provide a comprehensive overview of the genetics, biochemistry, and pharmacology of ADK and will then focus on pathologies and therapeutic interventions. Challenges to translate ADK-based therapies into clinical use will be discussed critically. PMID:23592612

  10. Potassium ion-dependent trehalose phosphorylase from halophilic Bacillus selenitireducens MLS10.

    PubMed

    Nihira, Takanori; Saito, Yuka; Chiku, Kazuhiro; Kitaoka, Motomitsu; Ohtsubo, Ken'ichi; Nakai, Hiroyuki

    2013-11-01

    We discovered a potassium ion-dependent trehalose phosphorylase (Bsel_1207) belonging to glycoside hydrolase family 65 from halophilic Bacillus selenitireducens MLS10. Under high potassium ion concentrations, the recombinant Bsel_1207 produced in Escherichia coli existed as an active dimeric form that catalyzed the reversible phosphorolysis of trehalose in a typical sequential bi bi mechanism releasing β-D-glucose 1-phosphate and D-glucose. Decreasing potassium ion concentrations significantly reduced thermal and pH stabilities, leading to formation of inactive monomeric Bsel_1207. PMID:24021648

  11. Adenosine triphosphate inhibition of yeast trehalase.

    PubMed

    Panek, A D

    1969-09-01

    Yeast trehalase has been found to be inhibited non-competitively by adenosine triphosphate. Such a biological control could explain the accumulation of trehalose during the stationary phase of the growth curve. PMID:5370287

  12. Role of adenosine receptors in caffeine tolerance

    SciTech Connect

    Holtzman, S.G.; Mante, S.; Minneman, K.P. )

    1991-01-01

    Caffeine is a competitive antagonist at adenosine receptors. Receptor up-regulation during chronic drug treatment has been proposed to be the mechanism of tolerance to the behavioral stimulant effects of caffeine. This study reassessed the role of adenosine receptors in caffeine tolerance. Separate groups of rats were given scheduled access to drinking bottles containing plain tap water or a 0.1% solution of caffeine. Daily drug intake averaged 60-75 mg/kg and resulted in complete tolerance to caffeine-induced stimulation of locomotor activity, which could not be surmounted by increasing the dose of caffeine. 5'-N-ethylcarboxamidoadenosine (0.001-1.0 mg/kg) dose dependently decreased the locomotor activity of caffeine-tolerant rats and their water-treated controls but was 8-fold more potent in the latter group. Caffeine (1.0-10 mg/kg) injected concurrently with 5-N-ethylcarboxamidoadenosine antagonized the decreases in locomotor activity comparably in both groups. Apparent pA2 values for tolerant and control rats also were comparable: 5.05 and 5.11. Thus, the adenosine-antagonist activity of caffeine was undiminished in tolerant rats. The effects of chronic caffeine administration on parameters of adenosine receptor binding and function were measured in cerebral cortex. There were no differences between brain tissue from control and caffeine-treated rats in number and affinity of adenosine binding sites or in receptor-mediated increases (A2 adenosine receptor) and decreases (A1 adenosine receptor) in cAMP accumulation. These results are consistent with theoretical arguments that changes in receptor density should not affect the potency of a competitive antagonist. Experimental evidence and theoretical considerations indicate that up-regulation of adenosine receptors is not the mechanism of tolerance to caffeine-induced stimulation of locomotor activity.

  13. Regulation of Lymphocyte Function by Adenosine

    PubMed Central

    Linden, Joel; Cekic, Caglar

    2014-01-01

    Adenosine regulates the interaction between lymphocytes and the vasculature and is important for controlling lymphocyte trafficking in response to tissue injury or infection. Adenosine can blunt the effects of T cell receptor (TCR) activation primarily by activating adenosine A2A receptors (A2AR) and signaling via cyclic AMP and protein kinase A (PKA). PKA reduces proximal TCR signaling by phosphorylation of C-terminal Src kinase (Csk), nuclear factor of activated T cells (NF-AT) and cyclic AMP response element binding protein (CREB). PKA activation can either enhance or inhibit the survival of T cells depending on the strength and duration of signaling. Inducible enzymes such as CD73 and CD39 regulate adenosine formation and degradation in vivo. The extravasation of lymphocytes through blood vessels is influenced by A2AR-mediated suppression of Intercellular Adhesion Molecule 1 (ICAM) expression on lymphocytes and diminished production of IFNγ and IFNγ-inducible chemokines that are chemotactic to activated lymphocytes. Adenosine also decreases the barrier function of vascular endothelium by activating A2BRs. In sum, adenosine signaling is influenced by tissue inflammation and injury through induction of receptors and enzymes and has generally inhibitory effects on lymphocyte migration into inflamed tissues due to PKA-mediated effects on adhesion molecules, IFNγ production and endothelial barrier function. PMID:22772752

  14. Adenosine receptor agonists attenuate and adenosine receptor antagonists exacerbate opiate withdrawal signs.

    PubMed

    Kaplan, G B; Sears, M T

    1996-01-01

    Previous studies have demonstrated a role for adenosine in mediating opiate effects. Adenosine receptors and their functions have been shown to be regulated by chronic opiate treatment. This study examines the role of adenosine receptors in the expression of opiate withdrawal behaviors. The effects of single doses of parenterally administered adenosine receptor subtype-selective agonists and antagonists on opiate withdrawal signs in morphine-dependent mice were measured. Mice received subcutaneous morphine pellet treatment for 72 h and then underwent naloxone-precipitated withdrawal after pretreatment with adenosinergic agents. Adenosine agonists attenuated different opiate withdrawal signs. The A1 agonist R-N6(phenylisopropyl)adenosine (0, 0.01, 0.02 mg/kg, IP) significantly reduced wet dog shakes and withdrawal diarrhea, while the A2a-selective agonist 2-p-(2-carboxethyl)phenylethylamino-5'-N-ethylcarboxamido adenosine or CGS 21680 (0, 0.01, 0.05 mg/kg, IP) significantly inhibited teeth chattering and forepaw treads. Adenosine receptor antagonists enhanced different opiate withdrawal signs. The adenosine A1 antagonist 1,3-dipropyl-8-cyclopentylxanthine (0, 1, 10 mg/kg, IP) significantly increased weight loss and the A2 antagonist, 3,7-dimethyl-1-propargylxanthine (0, 1 and 10 mg/kg, IP) enhanced wet dog shakes and withdrawal diarrhea. Treatment effects of adenosinergic agents were not due to nonspecific motor effects, as demonstrated by activity monitoring studies. These results support a role for adenosine receptors in the expression of opiate withdrawal and suggest the potential utility of adenosine agonists in its treatment. PMID:8741956

  15. Photoaffinity labeling of A1-adenosine receptors

    SciTech Connect

    Klotz, K.N.; Cristalli, G.; Grifantini, M.; Vittori, S.; Lohse, M.J.

    1985-11-25

    The ligand-binding subunit of the A1-adenosine receptor has been identified by photoaffinity labeling. A photolabile derivative of R-N6-phenylisopropyladenosine, R-2-azido-N6-p-hydroxyphenylisopropyladenosine (R-AHPIA), has been synthesized as a covalent specific ligand for A1-adenosine receptors. In adenylate cyclase studies with membranes of rat fat cells and human platelets, R-AHPIA has adenosine receptor agonist activity with a more than 60-fold selectivity for the A1-subtype. It competes for (TH)N6-phenylisopropyladenosine binding to A1-receptors of rat brain membranes with a Ki value of 1.6 nM. After UV irradiation, R-AHPIA binds irreversibly to the receptor, as indicated by a loss of (TH)N6-phenylisopropyladenosine binding after extensive washing; the Ki value for this photoinactivation is 1.3 nM. The p-hydroxyphenyl substituent of R-AHPIA can be directly radioiodinated to give a photoaffinity label of high specific radioactivity ( SVI-AHPIA). This compound has a KD value of about 1.5 nM as assessed from saturation and kinetic experiments. Adenosine analogues compete for SVI-AHPIA binding to rat brain membranes with an order of potency characteristic for A1-adenosine receptors. Dissociation curves following UV irradiation at equilibrium demonstrate 30-40% irreversible specific binding. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that the probe is photoincorporated into a single peptide of Mr = 35,000. Labeling of this peptide can be blocked specifically and stereoselectively by adenosine receptor agonists and antagonists in a manner which is typical for the A1-subtype. The results indicate that SVI-AHPIA identifies the ligand-binding subunit of the A1-adenosine receptor, which is a peptide with Mr = 35,000.

  16. Metal ion-dependent, reversible, protein filament formation by designed beta-roll polypeptides

    PubMed Central

    Scotter, Andrew J; Guo, Meng; Tomczak, Melanie M; Daley, Margaret E; Campbell, Robert L; Oko, Richard J; Bateman, David A; Chakrabartty, Avijit; Sykes, Brian D; Davies, Peter L

    2007-01-01

    Background A right-handed, calcium-dependent β-roll structure found in secreted proteases and repeat-in-toxin proteins was used as a template for the design of minimal, soluble, monomeric polypeptides that would fold in the presence of Ca2+. Two polypeptides were synthesised to contain two and four metal-binding sites, respectively, and exploit stacked tryptophan pairs to stabilise the fold and report on the conformational state of the polypeptide. Results Initial analysis of the two polypeptides in the presence of calcium suggested the polypeptides were disordered. The addition of lanthanum to these peptides caused aggregation. Upon further study by right angle light scattering and electron microscopy, the aggregates were identified as ordered protein filaments that required lanthanum to polymerize. These filaments could be disassembled by the addition of a chelating agent. A simple head-to-tail model is proposed for filament formation that explains the metal ion-dependency. The model is supported by the capping of one of the polypeptides with biotin, which disrupts filament formation and provides the ability to control the average length of the filaments. Conclusion Metal ion-dependent, reversible protein filament formation is demonstrated for two designed polypeptides. The polypeptides form filaments that are approximately 3 nm in diameter and several hundred nm in length. They are not amyloid-like in nature as demonstrated by their behaviour in the presence of congo red and thioflavin T. A capping strategy allows for the control of filament length and for potential applications including the "decoration" of a protein filament with various functional moieties. PMID:17908326

  17. Nucleoside transporter expression and adenosine uptake in the rat cochlea.

    PubMed

    Khan, Abdul F; Thorne, Peter R; Muñoz, David J B; Wang, Carol J H; Housley, Gary D; Vlajkovic, Srdjan M

    2007-02-12

    Even though extracellular adenosine plays multiple roles in the cochlea, the mechanisms that control extracellular adenosine concentrations in this organ are unclear. This study investigated the expression of nucleoside transporters and adenosine uptake in the rat cochlea. Reverse transcription-polymerase chain reaction revealed the expression of mRNA transcripts for two equilibrative (ENT1 and ENT2) and two concentrative (CNT1 and CNT2) nucleoside transporters. Exogenous adenosine perfused through the cochlear perilymphatic compartment was taken up by cells lining the compartment. Adenosine uptake was sensitive to changes in extracellular Na concentrations and inhibited by nitrobenzylthioinosine (an adenosine uptake blocker). The study suggests that the bi-directional nucleoside transport supports the uptake and recycling of purines and regulates the activation of adenosine receptors by altering adenosine concentrations in cochlear fluid spaces. PMID:17314663

  18. Novel adenosine receptors in rat hippocampus identification and characterization

    SciTech Connect

    Chin, J.H.; Mashman, W.E.; DeLorenzo, R.J.

    1985-05-06

    2-chloro(/sup 3/H)adenosine, a stable analog of adenosine, was used to investigate the presence of adenosine receptors in rat hippocampal membranes that may mediate the depressant effects of adenosine on synaptic transmission in this tissue. Equilibrium binding studies reveal the presence of a previously undescribed class of receptors with a K/sub D/ of 4.7 ..mu..M and a Bmax of 130 pmol/mg of protein. Binding is sensitive to alkylxanthines and to a number of adenosine-related compounds. The pharmacological properties of this binding site are distinct from those of the A1 and A2 adenosine receptors associated with adenylate cyclase. The results suggest that this adenosine binding site is a novel central purinergic receptor through which adenosine may regulate hippocampal excitability. 50 references, 2 figures, 1 table.

  19. Adenosine metabolism in phytohemagglutinin-stimulated human lymphocytes.

    PubMed Central

    Snyder, F F; Mendelsohn, J; Seegmiller, J E

    1976-01-01

    The association of a human genetic deficiency of adenosine deaminase activity with combined immunodeficiency prompted a study of the effects of adenosine and of inhibition of adenosine deaminase activity on human lymphocyte transformation and a detailed study of adenosine metabolism throughout phytohemagglutinin-induced blastogenesis. The adenosine deaminase inhibitor, coformycin, at a concentration that inhibited adenosine deaminase activity more than 95%, or 50 muM adenosine, did not prevent blastogenesis by criteria of morphology or thymidine incorporation into acid-precipitable material. The combination of coformycin and adenosine, however, substantially reduced both the viable cell count and the incorporation of thymidine into DNA in phytohemagglutinin-stimulated lymphocytes. Incubation of lymphocytes with phytohemagglutinin for 72 h produced a 12-fold increase in the rate of deamination and a 6-fold increase in phosphorylation of adenosine by intact lymphocytes. There was no change in the apparent affinity for adenosine with either deamination or phosphorylation. The increased rates of metabolism, apparent as early as 3 h after addition of mitogen, may be due to increased entry of the nucleoside into stimulated lymphocytes. Increased adenosine metabolism was not due to changes in total enzyme activity; after 72 h in culture, the ratios of specific activities in extracts of stimulated to unstimulated lymphocytes were essentially unchanged for adenosine kinase, 0.92, and decreased for adenosine deaminase, 0.44. As much as 38% of the initial lymphocyte adenosine deaminase activity accumulated extracellularly after a 72-h culture with phytohemagglutinin. In phytohemagglutinin-stimulated lymphocytes, the principal route of adenosine metabolism was phosphorylation at less than 5 muM adenosine, and deamination at concentrations greater than 5 muM. In unstimulated lymphocytes, deamination was the principal route of adenosine metabolism over the range of adenosine

  20. Extracellular formation and uptake of adenosine during skeletal muscle contraction in the rat: role of adenosine transporters.

    PubMed

    Lynge, J; Juel, C; Hellsten, Y

    2001-12-01

    1. The existence of adenosine transporters in plasma membrane giant vesicles from rat skeletal muscles and in primary skeletal muscle cell cultures was investigated. In addition, the contribution of intracellularly or extracellularly formed adenosine to the overall extracellular adenosine concentration during muscle contraction was determined in primary skeletal muscle cell cultures. 2. In plasma membrane giant vesicles, the carrier-mediated adenosine transport demonstrated saturation kinetics with Km = 177 +/- 36 microM and Vmax = 1.9 +/- 0.2 nmol x ml(-1) x s(-1) (0.7 nmol (mg protein)(-1) x s(-1)). The existence of an adenosine transporter was further evidenced by the inhibition of the carrier-mediated adenosine transport in the presence of NBMPR (nitrobenzylthioinosine; 72% inhibition) or dipyridamol (64% inhibition; P < 0.05). 3. In primary skeletal muscle cells, the rate of extracellular adenosine accumulation was 5-fold greater (P < 0.05) with electrical stimulation than without electrical stimulation. Addition of the adenosine transporter inhibitor NBMPR led to a 57% larger (P < 0.05) rate of extracellular adenosine accumulation in the electro-stimulated muscle cells compared with control cells, demonstrating that adenosine is taken up by the skeletal muscle cells during contractions. 4. Inhibition of ecto-5'-nucleotidase with AOPCP in electro-stimulated cells resulted in a 70% lower (P < 0.05) rate of extracellular adenosine accumulation compared with control cells, indicating that adenosine to a large extent is formed in the extracellular space during contraction. 5. The present study provides evidence for the existence of an NBMPR-sensitive adenosine transporter in rat skeletal muscle. Our data furthermore demonstrate that the increase in extracellular adenosine observed during electro-stimulation of skeletal muscle is due to production of adenosine in the extracellular space of skeletal muscle and that adenosine is taken up rather than released by the

  1. Adenosine reagent-free detection by co-immobilization of adenosine deaminase and phenol red on an optical biostrip.

    PubMed

    Bartzoka, Foteini; Venetsanou, Katerina; Clonis, Yannis

    2015-01-01

    Adenosine detection in human serum is important because this ribonucleoside has established clinical applications, modulating many physiological processes. Furthermore, a simple and cheap detection method is useful in adenosine production processes. Adenosine can be determined enzymatically using either S-adenosyl-homocysteine hydrolase and (3) [H]-adenosine, or adenosine kinase combined with GTP and luciferase, or an amperometric biosensor carrying adenosine deaminase (ADA), purine nucleoside phosphorylase, and xanthine oxidase. We developed a simple and cheap method relying on a transparent biostrip bearing ADA and the indicator phenol red (PR), co-immobilized to polyacrylamide, itself chemically adhered to a derivatized glass strip. The ADA-catalyzed conversion of adenosine to inosine and ammonia leads to a local pH alteration, changing the absorbance maximum of PR (from 425 to 567 nm), which is measured optically. The biostrip shows an analytical range 0.05-1.5 mM adenosine and is reusable when stored at 4 °C. When the biostrip was tested with serum, spiked with adenosine (70 and 100 μM), and filtered for protein and adenosine phosphates depletion, it showed good adenosine recovery. In summary, we show the proof-of-concept that adenosine can be determined reagent-free, at moderate sensitivity on an easy to construct, cheap, and reusable biostrip, based on commercially available molecular entities. PMID:25293641

  2. A corpora allata farnesyl diphosphate synthase in mosquitoes displaying a metal ion dependent substrate specificity.

    PubMed

    Rivera-Perez, Crisalejandra; Nyati, Pratik; Noriega, Fernando G

    2015-09-01

    Farnesyl diphosphate synthase (FPPS) is a key enzyme in isoprenoid biosynthesis, it catalyzes the head-to-tail condensation of dimethylallyl diphosphate (DMAPP) with two molecules of isopentenyl diphosphate (IPP) to generate farnesyl diphosphate (FPP), a precursor of juvenile hormone (JH). In this study, we functionally characterized an Aedes aegypti FPPS (AaFPPS) expressed in the corpora allata. AaFPPS is the only FPPS gene present in the genome of the yellow fever mosquito, it encodes a 49.6 kDa protein exhibiting all the characteristic conserved sequence domains on prenyltransferases. AaFPPS displays its activity in the presence of metal cofactors; and the product condensation is dependent of the divalent cation. Mg(2+) ions lead to the production of FPP, while the presence of Co(2+) ions lead to geranyl diphosphate (GPP) production. In the presence of Mg(2+) the AaFPPS affinity for allylic substrates is GPP > DMAPP > IPP. These results suggest that AaFPPS displays "catalytic promiscuity", changing the type and ratio of products released (GPP or FPP) depending on allylic substrate concentrations and the presence of different metal cofactors. This metal ion-dependent regulatory mechanism allows a single enzyme to selectively control the metabolites it produces, thus potentially altering the flow of carbon into separate metabolic pathways. PMID:26188328

  3. Quantitative analysis of the ion-dependent folding stability of DNA triplexes

    NASA Astrophysics Data System (ADS)

    Chen, Gengsheng; Chen, Shi-Jie

    2011-12-01

    A DNA triplex is formed through binding of a third strand to the major groove of a duplex. Due to the high charge density of a DNA triplex, metal ions are critical for its stability. We recently developed the tightly bound ion (TBI) model for ion-nucleic acids interactions. The model accounts for the potential correlation and fluctuations of the ion distribution. We now apply the TBI model to analyze the ion dependence of the thermodynamic stability for DNA triplexes. We focus on two experimentally studied systems: a 24-base DNA triplex and a pair of interacting 14-base triplexes. Our theoretical calculations for the number of bound ions indicate that the TBI model provides improved predictions for the number of bound ions than the classical Poisson-Boltzmann (PB) equation. The improvement is more significant for a triplex, which has a higher charge density than a duplex. This is possibly due to the higher ion concentration around the triplex and hence a stronger ion correlation effect for a triplex. In addition, our analysis for the free energy landscape for a pair of 14-mer triplexes immersed in an ionic solution shows that divalent ions could induce an attractive force between the triplexes. Furthermore, we investigate how the protonated cytosines in the triplexes affect the stability of the triplex helices.

  4. Divalent Ion Dependent Conformational Changes in an RNA Stem-Loop Observed by Molecular Dynamics

    PubMed Central

    2016-01-01

    We compare the performance of five magnesium (Mg2+) ion models in simulations of an RNA stem loop which has an experimentally determined divalent ion dependent conformational shift. We show that despite their differences in parametrization and resulting van der Waals terms, including differences in the functional form of the nonbonded potential, when the RNA adopts its folded conformation, all models behave similarly across ten independent microsecond length simulations with each ion model. However, when the entire structure ensemble is accounted for, chelation of Mg2+ to RNA is seen in three of the five models, most egregiously and likely artifactual in simulations using a 12-6-4 model for the Lennard-Jones potential. Despite the simple nature of the fixed point-charge and van der Waals sphere models employed, and with the exception of the likely oversampled directed chelation of the 12-6-4 potential models, RNA–Mg2+ interactions via first shell water molecules are surprisingly well described by modern parameters, allowing us to observe the spontaneous conformational shift from Mg2+ free RNA to Mg2+ associated RNA structure in unrestrained molecular dynamics simulations. PMID:27294370

  5. Divalent Ion Dependent Conformational Changes in an RNA Stem-Loop Observed by Molecular Dynamics.

    PubMed

    Bergonzo, Christina; Hall, Kathleen B; Cheatham, Thomas E

    2016-07-12

    We compare the performance of five magnesium (Mg(2+)) ion models in simulations of an RNA stem loop which has an experimentally determined divalent ion dependent conformational shift. We show that despite their differences in parametrization and resulting van der Waals terms, including differences in the functional form of the nonbonded potential, when the RNA adopts its folded conformation, all models behave similarly across ten independent microsecond length simulations with each ion model. However, when the entire structure ensemble is accounted for, chelation of Mg(2+) to RNA is seen in three of the five models, most egregiously and likely artifactual in simulations using a 12-6-4 model for the Lennard-Jones potential. Despite the simple nature of the fixed point-charge and van der Waals sphere models employed, and with the exception of the likely oversampled directed chelation of the 12-6-4 potential models, RNA-Mg(2+) interactions via first shell water molecules are surprisingly well described by modern parameters, allowing us to observe the spontaneous conformational shift from Mg(2+) free RNA to Mg(2+) associated RNA structure in unrestrained molecular dynamics simulations. PMID:27294370

  6. Internalization and desensitization of adenosine receptors

    PubMed Central

    Klaasse, Elisabeth C.; de Grip, Willem J.; Beukers, Margot W.

    2007-01-01

    Until now, more than 800 distinct G protein-coupled receptors (GPCRs) have been identified in the human genome. The four subtypes of the adenosine receptor (A1, A2A, A2B and A3 receptor) belong to this large family of GPCRs that represent the most widely targeted pharmacological protein class. Since adenosine receptors are widespread throughout the body and involved in a variety of physiological processes and diseases, there is great interest in understanding how the different subtypes are regulated, as a basis for designing therapeutic drugs that either avoid or make use of this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), a process that is followed by binding of arrestin proteins. This prevents receptors from activating downstream heterotrimeric G protein pathways, but at the same time allows activation of arrestin-dependent signalling pathways. Upon agonist treatment, adenosine receptor subtypes are differently regulated. For instance, the A1Rs are not (readily) phosphorylated and internalize slowly, showing a typical half-life of several hours, whereas the A2AR and A2BR undergo much faster downregulation, usually shorter than 1 h. The A3R is subject to even faster downregulation, often a matter of minutes. The fast desensitization of the A3R after agonist exposure may be therapeutically equivalent to antagonist occupancy of the receptor. This review describes the process of desensitization and internalization of the different adenosine subtypes in cell systems, tissues and in vivo studies. In addition, molecular mechanisms involved in adenosine receptor desensitization are discussed. PMID:18368531

  7. Neuroprotective effects of adenosine deaminase in the striatum.

    PubMed

    Tamura, Risa; Ohta, Hiroyuki; Satoh, Yasushi; Nonoyama, Shigeaki; Nishida, Yasuhiro; Nibuya, Masashi

    2016-04-01

    Adenosine deaminase (ADA) is a ubiquitous enzyme that catabolizes adenosine and deoxyadenosine. During cerebral ischemia, extracellular adenosine levels increase acutely and adenosine deaminase catabolizes the increased levels of adenosine. Since adenosine is a known neuroprotective agent, adenosine deaminase was thought to have a negative effect during ischemia. In this study, however, we demonstrate that adenosine deaminase has substantial neuroprotective effects in the striatum, which is especially vulnerable during cerebral ischemia. We used temporary oxygen/glucose deprivation (OGD) to simulate ischemia in rat corticostriatal brain slices. We used field potentials as the primary measure of neuronal damage. For stable and efficient electrophysiological assessment, we used transgenic rats expressing channelrhodopsin-2, which depolarizes neurons in response to blue light. Time courses of electrically evoked striatal field potential (eFP) and optogenetically evoked striatal field potential (optFP) were recorded during and after oxygen/glucose deprivation. The levels of both eFP and optFP decreased after 10 min of oxygen/glucose deprivation. Bath-application of 10 µg/ml adenosine deaminase during oxygen/glucose deprivation significantly attenuated the oxygen/glucose deprivation-induced reduction in levels of eFP and optFP. The number of injured cells decreased significantly, and western blot analysis indicated a significant decrease of autophagic signaling in the adenosine deaminase-treated oxygen/glucose deprivation slices. These results indicate that adenosine deaminase has protective effects in the striatum. PMID:26746865

  8. 2-Substituted adenosine derivatives: affinity and efficacy at four subtypes of human adenosine receptors.

    PubMed

    Gao, Zhan-Guo; Mamedova, Liaman K; Chen, Peiran; Jacobson, Kenneth A

    2004-11-15

    The affinity and efficacy at four subtypes (A(1), A(2A), A(2B) and A(3)) of human adenosine receptors (ARs) of a wide range of 2-substituted adenosine derivatives were evaluated using radioligand binding assays and a cyclic AMP functional assay in intact CHO cells stably expressing these receptors. Similar to previous studies of the N(6)-position, several 2-substituents were found to be critical structural determinants for the A(3)AR activation. The following adenosine 2-ethers were moderately potent partial agonists (K(i), nM): benzyl (117), 3-chlorobenzyl (72), 2-(3-chlorophenyl)ethyl (41), and 2-(2-naphthyl)ethyl (130). The following adenosine 2-ethers were A(3)AR antagonists: 2,2-diphenylethyl, 2-(2-norbornan)ethyl, R- and S-2-phenylbutyl, and 2-(2-chlorophenyl)ethyl. 2-(S-2-Phenylbutyloxy)adenosine as an A(3)AR antagonist right-shifted the concentration-response curve for the inhibition by NECA of cyclic AMP accumulation with a K(B) value of 212 nM, which is similar to its binding affinity (K(i) = 175 nM). These 2-substituted adenosine derivatives were generally less potent at the A(1)AR in comparison to the A(3)AR, but fully efficacious, with binding K(i) values over 100 nM. The 2-phenylethyl moiety resulted in higher A(3)AR affinity (K(i) in nM) when linked to the 2-position of adenosine through an ether group (54), than when linked through an amine (310) or thioether (1960). 2-[2-(l-Naphthyl)ethyloxy]adenosine (K(i) = 3.8 nM) was found to be the most potent and selective (>50-fold) A(2A) agonist in this series. Mixed A(2A)/A(3)AR agonists have been identified. Interestingly, although most of these compounds were extremely weak at the A(2B)AR, 2-[2-(2-naphthyl)ethyloxy]adenosine (EC(50) = 1.4 microM) and 2-[2-(2-thienyl)-ethyloxy]adenosine (EC(50) = 1.8 microM) were found to be relatively potent A(2B) agonists, although less potent than NECA (EC(50) = 140 nM). PMID:15476669

  9. 2-Substituted adenosine derivatives: affinity and efficacy at four subtypes of human adenosine receptors

    PubMed Central

    Gao, Zhan-Guo; Mamedova, Liaman K.; Chen, Peiran; Jacobson, Kenneth A.

    2012-01-01

    The affinity and efficacy at four subtypes (A1, A2A, A2B and A3) of human adenosine receptors (ARs) of a wide range of 2-substituted adenosine derivatives were evaluated using radioligand binding assays and a cyclic AMP functional assay in intact CHO cells stably expressing these receptors. Similar to previous studies of the N6-position, several 2-substituents were found to be critical structural determinants for the A3AR activation. The following adenosine 2-ethers were moderately potent partial agonists (Ki, nM): benzyl (117), 3-chlorobenzyl (72), 2-(3-chlorophenyl)ethyl (41), and 2-(2-naphthyl)ethyl (130). The following adenosine 2-ethers were A3AR antagonists: 2,2-diphenylethyl, 2-(2-norbornan)ethyl, R- and S-2-phenylbutyl, and 2-(2-chlorophenyl)ethyl. 2-(S-2-Phenylbutyloxy)a-denosine as an A3AR antagonist right-shifted the concentration–response curve for the inhibition by NECA of cyclic AMP accumulation with a KB value of 212 nM, which is similar to its binding affinity (Ki = 175 nM). These 2-substituted adenosine derivatives were generally less potent at the A1AR in comparison to the A3AR, but fully efficacious, with binding Ki values over 100 nM. The 2-phenylethyl moiety resulted in higher A3AR affinity (Ki in nM) when linked to the 2-position of adenosine through an ether group (54), than when linked through an amine (310) or thioether (1960). 2-[2-(l-Naphthyl)ethyloxy]adenosine (Ki = 3.8 nM) was found to be the most potent and selective (>50-fold) A2A agonist in this series. Mixed A2A/A3AR agonists have been identified. Interestingly, although most of these compounds were extremely weak at the A2BAR, 2-[2-(2-naphthyl)ethyloxy]adenosine (EC50 = 1.4 µM) and 2-[2-(2-thienyl)-ethyloxy]adenosine (EC50 = 1.8 (M) were found to be relatively potent A2B agonists, although less potent than NECA (EC50 = 140 nM). PMID:15476669

  10. Silk polymer-based adenosine release: therapeutic potential for epilepsy.

    PubMed

    Wilz, Andrew; Pritchard, Eleanor M; Li, Tianfu; Lan, Jing-Quan; Kaplan, David L; Boison, Detlev

    2008-09-01

    Adenosine augmentation therapies (AAT) make rational use of the brain's own adenosine-based seizure control system and hold promise for the therapy of refractory epilepsy. In an effort to develop an AAT compatible with future clinical application, we developed a novel silk protein-based release system for adenosine. Adenosine releasing brain implants with target release doses of 0, 40, 200, and 1000ng adenosine per day were prepared by embedding adenosine containing microspheres into nanofilm-coated silk fibroin scaffolds. In vitro, the respective polymers released 0, 33.4, 170.5, and 819.0ng adenosine per day over 14 days. The therapeutic potential of the implants was validated in a dose-response study in the rat model of kindling epileptogenesis. Four days prior to the onset of kindling, adenosine releasing polymers were implanted into the infrahippocampal cleft and progressive acquisition of kindled seizures was monitored over a total of 48 stimulations. We document a dose-dependent retardation of seizure acquisition. In recipients of polymers releasing 819ng adenosine per day, kindling epileptogenesis was delayed by one week corresponding to 18 kindling stimulations. Histological analysis of brain samples confirmed the correct location of implants and electrodes. We conclude that silk-based delivery of around 1000ng adenosine per day is a safe and efficient strategy to suppress seizures. PMID:18514814

  11. Adenosine Signaling During Acute and Chronic Disease States

    PubMed Central

    Karmouty-Quintana, Harry; Xia, Yang; Blackburn, Michael R.

    2013-01-01

    Adenosine is a signaling nucleoside that is produced following tissue injury, particularly injury involving ischemia and hypoxia. The production of extracellular adenosine and its subsequent signaling through adenosine receptors plays an important role in orchestrating injury responses in multiple organs. There are four adenosine receptors that are widely distributed on immune, epithelial, endothelial, neuronal and stromal cells throughout the body. Interestingly, these receptors are subject to altered regulation following injury. Studies in mouse models and human cells and tissues have identified that the production of adenosine and its subsequent signaling through its receptors plays largely beneficial roles in acute disease states, with the exception of brain injury. In contrast, if elevated adenosine levels are sustained beyond the acute injury phase, adenosine responses can become detrimental by activating pathways that promote tissue injury and fibrosis. Understanding when during the course of disease adenosine signaling is beneficial as opposed to detrimental and defining the mechanisms involved will be critical for the advancement of adenosine based therapies for acute and chronic diseases. The purpose of this review is to discuss key observations that define the beneficial and detrimental aspects of adenosine signaling during acute and chronic disease states with an emphasis on cellular processes such as inflammatory cell regulation, vascular barrier function and tissue fibrosis. PMID:23340998

  12. Adenosine diphosphate-degrading activity in placenta.

    PubMed

    Barradas, M; Khokher, M; Hutton, R; Craft, I L; Dandona, P

    1983-02-01

    1. The degradation of ADP by the placenta and umbilical artery was investigated. 2. Supernatants from incubations of finely chopped placental and umbilical arterial tissue were incubated with [14C]ADP for various durations from 0 to 30 min. 3. Products of ADP degradation were separated by thin-layer chromatography and radioactivity incorporated into each product was measured. 4. Placental supernatants induced a more rapid degradation of ADP than the umbilical artery supernatants. The main product of ADP degradation by placental supernatants at 30 min was adenosine, whereas that of umbilical artery was AMP. 5. This conversion by placenta of ADP, a potent platelet aggregator and vasoconstrictor, into adenosine, a potent platelet anti-aggregator and vasodilator, may be important in the maintenance of perfusion of the foetoplacental unit. PMID:6822058

  13. Adenosine thallium 201 myocardial perfusion scintigraphy

    SciTech Connect

    Verani, M.S. )

    1991-07-01

    Pharmacologic coronary vasodilation as an adjunct to myocardial perfusion imaging has become increasingly important in the evaluation of patients with coronary artery disease, in view of the large number of patients who cannot perform an adequate exercise test or in whom contraindications render exercise inappropriate. Adenosine is a very potent coronary vasodilator and when combined with thallium 201 scintigraphy produces images of high quality, with the added advantages of a very short half-life (less than 10 seconds) and the ability to adjust the dose during the infusion, which may enhance safety and curtail the duration of side effects. The reported sensitivity and specificity of adenosine thallium 201 scintigraphy for the detection of coronary artery disease are high and at least comparable with imaging after exercise or dipyridamole administration. 23 refs.

  14. Chemoelectrical energy conversion of adenosine triphosphate

    NASA Astrophysics Data System (ADS)

    Sundaresan, Vishnu Baba; Sarles, Stephen Andrew; Leo, Donald J.

    2007-04-01

    Plant and animal cell membranes transport charged species, neutral molecules and water through ion pumps and channels. The energy required for moving species against established concentration and charge gradients is provided by the biological fuel - adenosine triphosphate (ATP) -synthesized within the cell. The adenosine triphosphatase (ATPases) in a plant cell membrane hydrolyze ATP in the cell cytoplasm to pump protons across the cell membrane. This establishes a proton gradient across the membrane from the cell exterior into the cell cytoplasm. This proton motive force stimulates ion channels that transport nutrients and other species into the cell. This article discusses a device that converts the chemical energy stored in adenosine triphosphate into electrical power using a transporter protein, ATPase. The V-type ATPase proteins used in our prototype are extracted from red beet(Beta vulgaris) tonoplast membranes and reconstituted in a bilayer lipid membrane or BLM formed from POPC and POPS lipids. A pH7 medium that can support ATP hydrolysis is provided on both sides of the membrane and ATP is dissolved in the pH7 buffer on one side of the membrane. Hydrolysis of ATP results in the formation of a phosphate ion and adenosine diphosphate. The energy from the reaction activates ATPase in the BLM and moves a proton across the membrane. The charge gradient established across the BLM due to the reaction and ion transport is converted into electrical current by half-cell reference electrodes. The prototype ATPase cell with an effective BLM area of 4.15 mm2 carrying 15 μl of ATPase proteins was observed to develop a steady state peak power output of 70 nW, which corresponds to a specific power of 1.69 μW/cm2 and a current density of 43.4 μA/cm2 of membrane area.

  15. Prevalence of unidirectional Na+-dependent adenosine transport and altered potential for adenosine generation in diabetic cardiac myocytes.

    PubMed

    Podgorska, M; Kocbuch, K; Grden, M; Szutowicz, A; Pawelczyk, T

    2006-05-01

    Adenosine is an important physiological regulator of the cardiovascular system. The goal of our study was to assess the expression level of nucleoside transporters (NT) in diabetic rat cardiomyocytes and to examine the activities of adenosine metabolizing enzymes. Isolated rat cardiomyocytes displayed the presence of detectable amounts of mRNA for ENT1, ENT2, CNT1, and CNT2. Overall adenosine (10 microM) transport in cardiomyocytes isolated from normal rat was 36 pmol/mg/min. The expression level of equilibrative transporters (ENT1, ENT2) decreased and of concentrative transporters (CNT1, CNT2) increased in myocytes isolated from diabetic rat. Consequently, overall adenosine transport decreased by 30%, whereas Na(+)-dependent adenosine uptake increased 2-fold, and equilibrative transport decreased by 60%. The activity ratio of AMP deaminase/5'-nucleotidase in cytosol of normal cardiomyocytes was 11 and increased to 15 in diabetic cells. The activity of ecto-5'-nucleotidase increased 2-fold in diabetic cells resulting in a rise of the activity ratio of ecto-5'-nucleotidase/adenosine deaminase from 28 to 56.These results indicate that in rat cardiomyocytes diabetes alters activities of adenosine metabolizing enzymes in such a way that conversion of AMP to IMP is favored in the cytosolic compartment, whereas the capability to produce adenosine extracellularly is increased. This is accompanied by an increased unidirectional Na(+)-dependent uptake of adenosine and significantly reduced bidirectional adenosine transport. PMID:16369729

  16. Voltage and ion dependences of the slow currents which mediate bursting in Aplysia neurone R15.

    PubMed

    Adams, W B; Levitan, I B

    1985-03-01

    The previous paper described a slow depolarizing tail current, ID, and a slow hyperpolarizing tail current, IH, that are activated by action potentials and by brief depolarizing pulses in Aplysia neurone R15. ID and IH are necessary for the generation of bursting pace-maker activity in this cell. In this paper, the voltage and ion dependence of ID and IH are studied in an effort to determine the charge carriers for the two currents. When the slow currents are activated by brief depolarizing pulses delivered under voltage clamp in normal medium, an increase in the size of the pulse of 5-10 mV is usually sufficient to bring about full activation of ID. The apparent threshold in normal medium is approximately -20 mV. In medium in which K+ channels are blocked, full activation of an inward tail current that resembles ID requires increasing the pulse amplitude by only 1-2 mV. In contrast, IH is activated in a graded fashion over a 40 mV range of pulse amplitudes. After activating the currents with action potentials or with supramaximal pulses, ID remains an inward current and IH an outward current over a range of membrane potentials spanning -20 to -120 mV. In normal medium, ID is dependent on both extracellular Na+ concentration ( [Na+]o) and extracellular Ca2+ concentration ( [Ca2+]o). When K+ channels are blocked, ID can be supported by either [Na+]o or [Ca2+]o. IH depends only on [Ca2+]o as long as [Na+]o is at least 50 mM. Neither ID nor IH is decreased by decreasing the K+ gradient or by application of K+ channel blockers. These treatments increase somewhat the apparent amplitude of ID, probably by unmasking it from the large K+ tail current that follows the depolarizing pulse. A direct comparison in the same cell of the tetraethylammonium sensitivity of IH and of the Ca2+-activated K+ current demonstrates that these two currents flow through separate and distinct populations of channels. We conclude that in R15, ID arises in response to the triggering of an

  17. The molecular mechanism of ion-dependent gating in secondary transporters.

    PubMed

    Zhao, Chunfeng; Noskov, Sergei Yu

    2013-10-01

    LeuT-like fold Na-dependent secondary active transporters form a large family of integral membrane proteins that transport various substrates against their concentration gradient across lipid membranes, using the free energy stored in the downhill concentration gradient of sodium ions. These transporters play an active role in synaptic transmission, the delivery of key nutrients, and the maintenance of osmotic pressure inside the cell. It is generally believed that binding of an ion and/or a substrate drives the conformational dynamics of the transporter. However, the exact mechanism for converting ion binding into useful work has yet to be established. Using a multi-dimensional path sampling (string-method) followed by all-atom free energy simulations, we established the principal thermodynamic and kinetic components governing the ion-dependent conformational dynamics of a LeuT-like fold transporter, the sodium/benzyl-hydantoin symporter Mhp1, for an entire conformational cycle. We found that inward-facing and outward-facing states of Mhp1 display nearly the same free energies with an ion absent from the Na2 site conserved across the LeuT-like fold transporters. The barrier separating an apo-state from inward-facing or outward-facing states of the transporter is very low, suggesting stochastic gating in the absence of ion/substrate bound. In contrast, the binding of a Na2 ion shifts the free energy stabilizing the outward-facing state and promoting substrate binding. Our results indicate that ion binding to the Na2 site may also play a key role in the intracellular thin gate dynamics modulation by altering its interactions with the transmembrane helix 5 (TM5). The Potential of Mean Force (PMF) computations for a substrate entrance displays two energy minima that correspond to the locations of the main binding site S1 and proposed allosteric S2 binding site. However, it was found that substrate's binds to the site S1 ∼5 kcal/mol more favorable than that to the

  18. ATP- and adenosine-mediated signaling in the central nervous system: adenosine stimulates glutamate release from astrocytes via A2a adenosine receptors.

    PubMed

    Nishizaki, Tomoyuki

    2004-02-01

    Adenosine enhanced intracellular Ca(2+) concentrations in astrocytes via A(2a) adenosine receptors involving protein kinase A (PKA) activation. The Ca(2+) rise is inhibited by brefeldin A, an inhibitor of vesicular transport; but not by neomycin and U73122, phospholipase C inhibitors; xestospongin, an IP(3)-receptor inhibitor; ryanodine, a ryanodine-receptor inhibitor; TMB-8, an endoplasmic reticulum calcium-release blocker; octanol, a gap-junction inhibitor; or cadmium, a non-selective, calcium-channel blocker. Adenosine stimulates astrocytic glutamate release via an A(2a) adenosine receptors/PKA pathway, and the release is inhibited by the vesicular transport inhibitors brefeldin A and bafilomycin A1. A(2a) adenosine receptors and the ensuing PKA events, thus, are endowed with vesicular Ca(2+) release from an unknown intracellular calcium store and vesicular glutamate release from astrocytes. PMID:14978344

  19. Use of adenosine echocardiography for diagnosis of coronary artery disease

    SciTech Connect

    Zoghbi, W.A. )

    1991-07-01

    Two-dimensional echocardiography combined with exercise is sensitive and specific in the detection of coronary artery disease (CAD) by demonstrating transient abnormalities in wall motion. Frequently, however, patients cannot achieve maximal exercise because of various factors. Pharmacologic stress testing with intravenous adenosine was evaluated as a means of detecting CAD in a noninvasive manner. Patients with suspected CAD underwent echocardiographic imaging and simultaneous thallium 201 single-photon emission computed tomography during the intravenous administration of 140 micrograms/kg/min of adenosine. An increase in heart rate, decrease in blood pressure, and increase in double product were observed during adenosine administration. Initial observations revealed that wall motion abnormalities were induced by adenosine in areas of perfusion defects. The adenosine infusion was well tolerated, and symptoms disappeared within 1 to 2 minutes after termination of the infusion. Therefore preliminary observations suggest that adenosine echocardiography appears to be useful in the assessment of CAD.

  20. Characterization of adenosine receptors involved in adenosine-induced bronchoconstriction in allergic rabbits.

    PubMed Central

    el-Hashim, A.; D'Agostino, B.; Matera, M. G.; Page, C.

    1996-01-01

    1. Recent work has suggested that adenosine may be involved in asthma via the activation of A1 receptors. However, the role of the recently cloned A3 receptor in airways is largely unknown. In the present study, we have investigated the role of the A3 receptor in adenosine-induced bronchoconstriction in allergic rabbits. 2. Aerosol challenge of antigen (Ag) immunized rabbits with the adenosine precursor, adenosine 5'-monophosphate (AMP), resulted in a dose-dependent fall in dynamic compliance (Cdyn). The maximum fall in Cdyn in these rabbits was significantly greater than that in litter matched, sham immunized animals (P < 0.05). However, there was no significant difference in the maximum increase in airways resistance (Rt) between Ag and sham immunized rabbits (P > 0.05). 3. Aerosol challenge of Ag immunized rabbits with cyclopentyl-adenosine (CPA) (A1-receptor agonist) elicited a dose-dependent fall in Cdyn in Ag immunized rabbits and the maximum fall in Cdyn in these rabbits was significantly greater than that observed in sham immunized rabbits (P < 0.05). Similarly, CPA induced dose-dependent increases in R1 in Ag immunized rabbits whereas sham immunized rabbits failed to respond to CPA within the same dose range. The maximum increase in RL in Ag immunized rabbits was significantly greater than that of sham immunized rabbits (P < 0.05). 4. Aerosol challenge of either Ag or sham immunized rabbits with the A3 agonist aminophenylethyladenosine (APNEA) did not elicit dose-dependent changes in either RL or Cdyn. Moreover, there was no significant difference in the maximum response, measured by either parameter, between the two animal groups (P > 0.05). 5. These data provide further evidence for a role of the A1 receptor in the airways, but do not support a role for the A3 receptor in adenosine-induced bronchoconstriction in the allergic rabbit. PMID:8937732

  1. A Metabolic Immune Checkpoint: Adenosine in Tumor Microenvironment

    PubMed Central

    Ohta, Akio

    2016-01-01

    Within tumors, some areas are less oxygenated than others. Since their home ground is under chronic hypoxia, tumor cells adapt to this condition by activating aerobic glycolysis; however, this hypoxic environment is very harsh for incoming immune cells. Deprivation of oxygen limits availability of energy sources and induces accumulation of extracellular adenosine in tumors. Extracellular adenosine, upon binding with adenosine receptors on the surface of various immune cells, suppresses pro-inflammatory activities. In addition, signaling through adenosine receptors upregulates a number of anti-inflammatory molecules and immunoregulatory cells, leading to the establishment of a long-lasting immunosuppressive environment. Thus, due to hypoxia and adenosine, tumors can discourage antitumor immune responses no matter how the response was induced, whether it was spontaneous or artificially introduced with a therapeutic intention. Preclinical studies have shown the significance of adenosine in tumor survival strategy by demonstrating tumor regression after inactivation of adenosine receptors, inhibition of adenosine-producing enzymes, or reversal of tissue hypoxia. These promising results indicate a potential use of the inhibitors of the hypoxia–adenosine pathway for cancer immunotherapy. PMID:27066002

  2. Relationship of Cotton Fiber Calcium and Magnesium Contents on Dye Uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton from a single bale was processed into knit fabrics and prepared for dyeing. Following scouring, fabrics were soaked in either a metal sequestering solution or a water solution, bleached and dyed using 5 dye shades from both reatice and direct dye classes. Results indicate that removal of re...

  3. Simultaneously detection of calcium and magnesium in various samples by calmagite and chemometrics data processing.

    PubMed

    Rasouli, Zolaikha; Ghavami, Raouf

    2016-12-01

    The current study describes results of the application of radial basis function-partial least squares (RBF-PLS), partial robust M-regression (PRM), singular value decomposition (SVD), evolving factor analysis (EFA), multivariate curve resolution with alternating least squares (MCR-ALS) and rank annihilation factor analysis (RAFA) methods for the purposes of simultaneous determination of trace amounts calcium (Ca(2+)) and magnesium (Mg(2+)) and exploratory analysis based on their colored complexes formation with 1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulfonic acid (calmagite) as chromomeric reagent. The complex formation Ca(2+) and Mg(2+) with calmagite was investigated under pH10.20. The performance of RBF-PLS model in detection of minerals was compared with PRM as a linear model. The pure concentration and spectral profiles were obtained using MCR-ALS. EFA and SVD were used to distinguish the number species. The stability constants of the complexes were derived using RAFA. Finally, RBF-PLS was utilized for simultaneous determination of minerals in pharmaceutical formulation and various vegetable samples. PMID:27341399

  4. Relative importance of calcium and magnesium in hardness-based modification of copper toxicity

    SciTech Connect

    Welsh, P.G.; Lipton, J.; Chapman, G.A.; Podrabsky, T.L.

    2000-06-01

    Because of the relationship between water hardness and the toxicity of many metals, total hardness is used as a model parameter to calculate ambient water quality criteria for copper and other metals. However, the relative contribution of the Ca and Mg components of total hardness as modifiers of metals toxicity is not considered in the water quality criteria. Acute Cu toxicity was measured in rainbow trout (Oncorhynchus mykiss) and chinook salmon (O. tshawytscha) swim-up fry in laboratory waters that were formulated to have similar total hardness and alkalinity but different Ca and Mg concentrations. Experiments were performed at nominal total hardness values of 40 and 90 mg/L (as CaCO{sub 3}). In four paired toxicity tests, acute Cu toxicity was significantly lower, i.e., 96-h LC50s were higher, in laboratory waters containing proportionately more Ca (Ca:Mg molar ratios of 1.5--5.2) than in waters containing less Ca (Ca:Mg molar ratios of 0.2--0.8). the relative increase in the 96-h Cu LC50 at higher Ca concentrations, but similar total hardness concentrations, was between 29 and 86% when the low Ca treatment was similar to American Society for Testing and Materials laboratory water. Failure to account for differences in Ca when matching or adjusting for total hardness thus exerts an important influence on the prediction of metal toxicity. These differences must be addressed in water-effect ratio testing in which paired tests with laboratory and site waters are conducted.

  5. Factors affecting ex-situ aqueous mineral carbonation using calcium and magnesium silicate minerals

    SciTech Connect

    Gerdemann, Stephen J.; Dahlin, David C.; O'Connor, William K.; Penner, Larry R.; Rush, G.E.

    2004-01-01

    Carbonation of magnesium- and calcium-silicate minerals to form their respective carbonates is one method to sequester carbon dioxide. Process development studies have identified reactor design as a key component affecting both the capital and operating costs of ex-situ mineral sequestration. Results from mineral carbonation studies conducted in a batch autoclave were utilized to design and construct a unique continuous pipe reactor with 100% recycle (flow-loop reactor). Results from the flow-loop reactor are consistent with batch autoclave tests, and are being used to derive engineering data necessary to design a bench-scale continuous pipeline reactor.

  6. Equilibrium and kinetic studies on the interaction of tetracyclines with calcium and magnesium.

    PubMed

    Martin, S R

    1979-11-01

    The interaction of Ca2+ and Mg2+ with three Tetracycline antibiotics (tetracycline, chlorotetracycline, and oxytetracycline) has been investigated. Spectrophotometric measurements have been used to determine the apparent association constant for this interaction as a function of pH. It is shown that the results are consistent with a model in which the metal ion can form complexes with both the fully-deprotonated and mono-protonated forms of the Tetracycline. The temperature-jump relaxation method has been used to measure the kinetics of formation of the complexes of Mg2+ with the Tetracyclines. The results are compared with those of previous studies of Mg2+ complex formation reactions and it is shown that the data is consistent with the normal dissociative model. A possible role for metal ion chelation in the mechanism of antibacterial action of the Tetracyclines is discussed. PMID:16997226

  7. Bioadsorption Behavior of Rhodococcus Opacus on the Surface of Calcium and Magnesium Minerals

    NASA Astrophysics Data System (ADS)

    Li, Hongxu; Zhang, Mingming; Li, Chao; Yang, Xie; Li, An; Zhang, Lifeng

    2015-02-01

    The surface properties of minerals can be influenced and changed by microbial activities when microorganisms adhere to the mineral surface. The change of mineral surface properties and thus mineral floatability can be used to separate gangues from valuable minerals. This study investigated the Rhodococcus opacus ( R. opacus) adsorption behavior on the surfaces of calcite, serpentine, and dolomite by bioadhesive test, contact angle measurements, Zeta potential, Fourier transform infrared spectroscopy (FTIR) spectra, and scanning electron microscopy (SEM). The results showed that R. opacus could be absorbed well onto the surfaces of calcite, serpentine, and dolomite in a few minutes, with adsorption rate up to 96%. The cell adsorption was dependent on the pH value and the most suitable pH is 7.2, whereas no significant influence of temperature on adsorption was found. Increasing pulp density could provide more adsorption sites to R. opacus cells and increase the adsorption rate consequently. The contact angle of three minerals decreased after R. opacus attached, which indicated that the dispersibility of the mineral surface was improved and in favor of being separated. Zeta potential measurements showed that the cell with the charge was opposite to that of minerals on a broad of pH value. The SEM images showed that R. opacus attached very tightly onto the mineral surface, with a large number of small mineral particles gathered around the cell. FTIR spectra showed the presence of polymer groups on the cell wall that could have given a net charge on the mineral surface.

  8. Calcium and magnesium transport by in situ mitochondria: electron probe analysis of vascular smooth muscle

    SciTech Connect

    Broderick, R.; Somlyo, A.P.

    1987-10-01

    The extent, time course, and reversibility of mitochondrial Ca/sup 2 +/ uptake secondary to cellular Ca/sup 2 +/ influx stimulated by massive Na+ efflux were evaluated by electron probe microanalysis of rabbit portal vein smooth muscle. Strips of portal vein were Na+ loaded for 3 hours at 37/sup 0/C in a K+-free 1 mM ouabain solution, after which rapid Na+ efflux was induced by washing with a Na+-free K+-Li+ solution (1 mM ouabain). Li+ washing Na+-loaded portal vein produced a large transient contraction accompanied by an increase (over 100-fold) in mitochondrial Ca/sup 2 +/ and also significant (p less than 0.05) increases in phosphorus and Mg/sup 2 +/. The Ca/sup 2 +/ loading of the mitochondria was reversed during prolonged Li+ wash, and by 2 hours, mitochondrial Ca/sup 2 +/, Mg/sup 2 +/, and phosphorus had returned to control levels. The maximal contractile response to stimulation remained normal, demonstrating that pathologic Ca/sup 2 +/ loading of mitochondria is reversible in situ and compatible with normal maximal force developed by the smooth muscle. Mitochondrial Ca/sup 2 +/ and phosphorus uptake were reduced but still significant when the Li+ wash contained 0.2 mM Ca/sup 2 +/ or when ouabain was omitted. The fact that mitochondrial Ca/sup 2 +/ loading accompanied submaximal contractions during 0.2 mM Ca/sup 2 +/-Li wash suggests supranormal affinity of mitochondria for Ca/sup 2 +/ and may be due, in part, to reverse operation of the mitochondrial Na+-Ca/sup 2 +/ exchanger. Mitochondrial Ca/sup 2 +/, Mg/sup 2 +/, and phosphorus uptake were eliminated when the Li+ wash was performed at 2/sup 0/C or when the wash contained no Ca/sup 2 +/.

  9. Nitrogen and phosphorus leaching as affected by gypsum amendment and exchangeable calcium and magnesium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The movement of N and P from the soil by leaching contributes to losses from agricultural land and represents an important environmental and human health concern. The objective of this study was to evaluate the effect of gypsum amendment and the resultant impact of different levels of exchangeable C...

  10. Decadal changes in potassium, calcium, and magnesium in a deciduous forest soil

    SciTech Connect

    Mulholland, Patrick J; Johnson, Dale W.; Todd Jr, Donald E; Trettin, Carl

    2008-01-01

    Decadal changes in soil exchangeable K{sup +}, Ca{sup 2+}, and Mg{sup 2+} concentrations and contents from 1972 to 2004 in eight intensively monitored plots on Walker Branch Watershed were compared with estimates of increments or decrements in vegetation and detritus. The results from these eight plots compared favorably with those from a more extensive set from 24 soil sampling plots sampled in 1972 and 2004. Increases in exchangeable K{sup +} were noted between 1972 and 1982, but few changes were noted between 1982 and 2004 despite significant increments in vegetation and detritus and significant potential losses by leaching. Total K contents of soils in the 0- to 60-cm sampling depth were very large and a slight amount of weathering could have replenished the K{sup +} lost from exchanges sites. With one notable exception, exchangeable Ca{sup 2+} and Mg{sup 2+} concentrations and contents decreased continuously during the sampling period. Decreases in exchangeable Ca{sup 2+} could be attributed mostly to increments in biomass and detritus, whereas decreases in exchangeable Mg{sup 2+} could not and were attributed to leaching. The major exception to these patterns was in the case of exchangeable Ca{sup 2+}, where significant increases were noted in one plot and attributed to Ca release from the decomposition of Ca-rich coarse woody debris from oak (Quercus spp.) mortality. With minor exceptions, soils and changes in soils among the eight intensively sampled core plots were similar to those in a more extensive set of plots distributed across the watershed. This study shows that averaging among plots can mask significant and important spatial patterns in soil change that must be taken into account in assessing long-term trends.

  11. Relief of Casein Inhibition of Bacillus stearothermophilus by Iron, Calcium, and Magnesium1

    PubMed Central

    Ashton, D. H.; Busta, F. F.; Warren, J. A.

    1968-01-01

    Growth of Bacillus stearothermophilus strain NCA 1518 Smooth in Dextrose Tryptone Agar (DTA) was inhibited by sodium caseinate. Binding studies indicated that sodium caseinate, when present in DTA, had the capacity to effect an iron deficiency which could cause inhibition of growth. Additions of essential cations, iron (1 mM), calcium (5 mM), magnesium (10 mM), or hydrogen ion (pH 5.7), relieved inhibition. Responses to and interactions among these relief factors were analyzed statistically. Equations were fitted to the data and were used to estimate responses to all treatment combinations within the ranges tested. Results from these studies indicated that calcium, magnesium, and hydrogen ion acted by decreasing the binding capacity of the protein for iron, rendering this metal available for metabolic needs. Evidence was obtained that ferrous rather than ferric iron was the limiting factor in DTA containing sodium caseinate. PMID:5694503

  12. Dietary calcium and magnesium supplements in spontaneously hypertensive rats and isolated arterial reactivity.

    PubMed Central

    Mäkynen, H.; Kähönen, M.; Arvola, P.; Wuorela, H.; Vapaatalo, H.; Pörsti, I.

    1995-01-01

    1. High calcium diet attenuates the development of hypertension but an associated undesirable effect is that Mg2+ loss to the urine is enhanced. Therefore, we studied the effects of high calcium diet alone and in combination with increased magnesium intake on blood pressure and arterial function. 2. Forty-eight young spontaneously hypertensive rats (SHR) were allocated into four groups, the dietary contents of Ca2+ and Mg2+ being: 1.1%, 0.2% (SHR); 2.5%, 0.2% (Ca-SHR); 2.5%, 0.8% (CaMg-SHR); and 1.1%, 0.8% (Mg-SHR), respectively. Development of hypertension was followed for 13 weeks, whereafter electrolyte balance, lymphocyte intracellular free calcium ([Ca2+]i), and mesenteric arterial responses in vitro were examined. Forty normotensive Wistar-Kyoto (WKY) rats were investigated in a similar manner. 3. Calcium supplementation comparably attenuated the development of Lypertension during normal and high magnesium intake in SHR, with an associated reduced lymphocyte [Ca2+]i and increased Mg2+ loss to the urine. 4. Endothelium-dependent arterial relaxation to acetylcholine was augmented in Ca-SHR and CaMg-SHR, while the relaxations to isoprenaline and the nitric oxide donor SIN-1 were similar in all SHR groups. Relaxation responses induced by the return of K+ to the organ bath upon precontractions in K(+)-free solution were used to evaluate the function of arterial Na+, K(+)-ATPase. The rate of potassium relaxation was similar in Ca-SHR and CaMg-SHR and faster than in untreated SHR.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8564205

  13. Ionised concentrations in calcium and magnesium buffers: Standards and precise measurement are mandatory.

    PubMed

    McGuigan, John A S; Kay, James W; Elder, Hugh Y

    2016-09-01

    In Ca(2+) and Mg(2+) buffer solutions the ionised concentrations ([X(2+)]) are either calculated or measured. Calculated values vary by up to a factor of seven due to the following four problems: 1) There is no agreement amongst the tabulated constants in the literature. These constants have usually to be corrected for ionic strength and temperature. 2) The ionic strength correction entails the calculation of the single ion activity coefficient, which involves non-thermodynamic assumptions; the data for temperature correction is not always available. 3) Measured pH is in terms of activity i.e. pHa. pHa measurements are complicated by the change in the liquid junction potentials at the reference electrode making an accurate conversion from H(+) activity to H(+) concentration uncertain. 4) Ligands such as EGTA bind water and are not 100% pure. Ligand purity has to be measured, even when the [X(2+)] are calculated. The calculated [X(2+)] in buffers are so inconsistent that calculation is not an option. Until standards are available, the [X(2+)] in the buffers must be measured. The Ligand Optimisation Method is an accurate and independently verified method of doing this (McGuigan & Stumpff, Anal. Biochem. 436, 29, 2013). Lack of standards means it is not possible to compare the published [Ca(2+)] in the nmolar range, and the apparent constant (K(/)) values for Ca(2+) and Mg(2+) binding to intracellular ligands amongst different laboratories. Standardisation of Ca(2+)/Mg(2+) buffers is now essential. The parameters to achieve this are proposed. PMID:26975789

  14. The influence of lithium on calcium and magnesium homeostasis in serum and tissues of rats.

    PubMed

    Kiełczykowska, Małgorzata; Pasternak, Kazimierz; Musik, Irena

    2003-01-01

    Lithium is used in medicine. However, its administration can have negative side effects, disturb the water-electrolyte equilibrium and affect the level of essential elements. For these reasons the influence of oral lithium intoxication at the dose of 150 mg Li dm(-3) on magnesium and calcium levels in serum and tissues of rats was investigated. The concentration of Mg and Ca in serum increased throughout the experiment. The concentration of magnesium in tissues decreased after three weeks in liver, kidney, brain and femoral muscle. The trend of the changes of calcium tissue concentration was opposite to the one observed in the case of magnesium. PMID:15323205

  15. Nitrogen, phosphorus, potassium, calcium and magnesium release from two compressed fertilizers: column experiments

    NASA Astrophysics Data System (ADS)

    Fernández-Sanjurjo, M. J.; Alvarez-Rodríguez, E.; Núñez-Delgado, A.; Fernández-Marcos, M. L.; Romar-Gasalla, A.

    2014-07-01

    We used soil columns to study nutrients release from two compressed NPK fertilizers. The columns were filled with soil material from the surface horizon of a granitic soil. Tablets of two slow-release NPK fertilizers (11-18-11 or 8-8-16) were placed into the soil, and then water was percolated through the columns in a saturated regime. Percolates were analyzed for N, P, K, Ca and Mg. These nutrients were also determined in soil and fertilizer tablets at the end of the trials. Nutrient concentrations were high in the first percolates, reaching a steady state when 1426 mm water have percolated, which is equivalent to approximately 1.5 years of rainfall in the geographic area. In the whole trial, both tablets lost more than 80% of their initial N, P and K contents. However, K, Ca and Mg were the most leached, whereas N and P were lost in leachates to a lesser extent. Nutrient release was slower from the tablet with composition 8-8-16 than from the 11-18-11 fertilizer. In view of that, the 8-8-16 tablet can be considered more adequate for crops with a nutrient demand sustained over time. At the end of the trial, the effects of these fertilizers on soil chemical parameters were still evident.

  16. Nitrogen, phosphorus, potassium, calcium and magnesium release from two compressed fertilizers: column experiments

    NASA Astrophysics Data System (ADS)

    Fernández-Sanjurjo, M. J.; Alvarez-Rodríguez, E.; Núñez-Delgado, A.; Fernández-Marcos, M. L.; Romar-Gasalla, A.

    2014-12-01

    The objective of this work was to study nutrients release from two compressed nitrogen-potassium-phosphorous (NPK) fertilizers. In the Lourizán Forest Center, tablet-type controlled-release fertilizers (CRF) were prepared by compressing various mixtures of fertilizers without covers or binders. We used soil columns (50 cm long and 7.3 cm inner diameter) that were filled with soil from the surface layer (0-20 cm) of an A horizon corresponding to a Cambic Umbrisol. Tablets of two slow-release NPK fertilizers (11-18-11 or 8-8-16) were placed into the soil (within the first 3 cm), and then water was percolated through the columns in a saturated regime for 80 days. Percolates were analyzed for N, P, K+, Ca2+ and Mg2+. These elements were also determined in soil and fertilizer tablets at the end of the trials. Nutrient concentrations were high in the first leachates and reached a steady state when 1426 mm of water had been percolated, which is equivalent to approximately 1.5 years of rainfall in this geographic area. In the whole trial, both tablets lost more than 80% of their initial N, P and K contents. However, K+, Ca2+ and Mg2+ were the most leached, whereas N and P were lost in leachates to a lesser extent. Nutrient release was slower from the tablet with a composition of 8-8-16 than from the 11-18-11 fertilizer. In view of that, the 8-8-16 tablet can be considered more adequate for crops with a nutrient demand sustained over time. At the end of the trial, the effects of these fertilizers on soil chemical parameters were still evident, with a significant increase of pH, available Ca2+, Mg2+, K+, P and effective cation exchange capacity (eCEC) in the fertilized columns, as well as a significant decrease in exchangeable Al3+, reaching values < 0.08 cmol (+) kg-1.

  17. Treatment of cooling tower blowdown water containing silica, calcium and magnesium by electrocoagulation.

    PubMed

    Liao, Z; Gu, Z; Schulz, M C; Davis, J R; Baygents, J C; Farrell, J

    2009-01-01

    This research investigated the effectiveness of electrocoagulation using iron and aluminium electrodes for treating cooling tower blowdown (CTB) waters containing dissolved silica (Si(OH)(4)), Ca(2 + ) and Mg(2 + ). The removal of each target species was measured as a function of the coagulant dose in simulated CTB waters with initial pH values of 5, 7, and 9. Experiments were also performed to investigate the effect of antiscaling compounds and coagulation aids on hardness ion removal. Both iron and aluminum electrodes were effective at removing dissolved silica. For coagulant doses < or =3 mM, silica removal was a linear function of the coagulant dose, with 0.4 to 0.5 moles of silica removed per mole of iron or aluminium. Iron electrodes were only 30% as effective at removing Ca(2 + ) and Mg(2 + ) as compared to silica. There was no measurable removal of hardness ions by aluminium electrodes in the absence of organic additives. Phosphonate based antiscaling compounds were uniformly effective at increasing the removal of Ca(2 + ) and Mg(2 + ) by both iron and aluminium electrodes. Cationic and amphoteric polymers used as coagulation aids were also effective at increasing hardness ion removal. PMID:19901466

  18. Effects of boron supplements on bones from rats fed calcium and magnesium deficient diets

    SciTech Connect

    McCoy, H.; Irwin, A.; Kenney, M.A.; Williams, L. )

    1991-03-15

    Sixty female, weanling rats were fed, for 6 wks, diets providing: casein, 20; CHO, 40; fat, 40. Vitamins and minerals, except Ca and Mg, were fed according to AIN'76 recommendations. Gp A (control) was fed 100% AIN Ca, Mg and P with no boron (B) added. Gps CD and CD+B were fed 30% AIN Ca and 100% AIN Mg and P; Gps MD and MD+B were fed 20% AIN Mg and 100% AIN Ca and P; Gps CMD and CMD+B were fed 20% AIN Mg, 30% AIN Ca and 100% AIN P. The +B groups were supplemented with B at 12 mcg/g diet. Femurs (F) and 2 vertebrae (V) were scraped clean, weighed, sealed in saline-wet gauze, and refrigerated overnight. Bones were equilibrated at {sup {approximately}}25C. F lengths and diameters at the breakpoint were measured before a 3-point flexure test. V were subjected to a compression test. Maximum force (kg) at breakpoint was recorded. Data for right and left F and for 2 V were pooled. Although DIET' (CD, MD, CMD) affected numerous characteristics of F and V, B supplementation of diets affected only % moisture in F, Ca concentration in dry F and in F ash for CD and CMD diets. Interactions between B and diet affected F Mg concentrations in bone and in ash. Group CMD+B had higher Mg/g F than CMD. B increased Mg/g ash for CMD, decreased it for CD and did not affect it for MD.

  19. Effects of calcium and magnesium salts on nickel subsulfide carcinogenicity in Fischer rats.

    PubMed

    Kasprzak, K S; Quander, R V; Poirier, L A

    1985-08-01

    The effects of calcium or magnesium salts administered by one of three different routes on the formation of muscle tumors by nickel subsulfide (Ni3S2) in Fischer F344 rats were determined. Eleven groups of 20 weanling male rats each received a single injection of 2.5 mg (31 mumol Ni) Ni3S2 into the thigh muscles of both hind limbs (i.m.). Then the rats were fed 3% calcium acetate (CaAcet)- or 3% magnesium acetate (MgAcet)-supplemented diets for 3 and 6 months, or were injected s.c. three times weekly, with 0.16 mmol doses of CaAcet/kg/injection, or with 2 mmol doses of MgAcet/kg/injection, for 1 or 4 months. Two other groups of 20 rats were injected i.m. with 2.5 mg (31 mumol Ni) of Ni3S2 mixed with 6.2 mg (62 mumol Ca) of calcium carbonate (CaCarb), or with 6.3 mg (62 mumol Mg) of magnesium basic carbonate (MgCarb). The control groups of rats received single i.m. injections of the 0.15 M saline vehicle, 6.2 mg CaCarb, and 6.3 mg MgCarb, or s.c. injections of 0.15 M saline, or 4 mmol sodium acetate, NaAcet/kg/injection, three times weekly for 4 months. After 18 months, injection site tumors were found: (i) in 70-90% of the rats injected i.m. with Ni3S2 and fed standard diet or the diets containing CaAcet or MgAcet, with no significant differences among the groups; (ii) in 95-100% of the rats given i.m. Ni3S2 and then treated with multiple s.c. injections of saline, NaAcet, CaAcet or MgAcet, with no significant differences among the groups; (iii) in 85% of rats injected i.m. with Ni3S2 + CaCarb, and (iv) in 25% of the rats injected i.m. with Ni3S2 + MgCarb. No tumors developed in the control rats. The admixtures of CaCarb or MgCarb to Ni3S2 did not affect the mobilization of nickel from the injection site. They did, however, influence the cellular responses to Ni3S2 in early stages, from 3 days to 22 weeks, after the injection. MgCarb, unlike CaCarb, strongly decreased the necrosis and increased macrophage proliferation at the Ni3S2 injection site. It also delayed the occurrence and proliferation of histiocytic-stromal cells, and prevented the occurrence of altered myoblasts. PMID:4017185

  20. Effects of adenosine, adenosine triphosphate and structural analogues on glucagon secretion from the perfused pancreas of rat in vitro.

    PubMed Central

    Chapal, J.; Loubatières-Mariani, M. M.; Roye, M.; Zerbib, A.

    1984-01-01

    The effects of adenosine, adenosine triphosphate (ATP) and structural analogues have been studied on glucagon secretion from the isolated perfused pancreas of the rat in the presence of glucose (2.8 mM). Adenosine induced a transient increase of glucagon secretion. This effect was concentration-dependent in the range of 0.165 to 165 microM. ATP also induced an increase, but the effect was no greater at 165 microM than at 16.5 microM. 2-Chloroadenosine, an analogue more resistant to metabolism or uptake systems than adenosine, was more effective. Among the three structural analogues of ATP or ADP studied, beta, gamma-methylene ATP which can be hydrolyzed into AMP and adenosine had an effect similar to adenosine or ATP at the same concentrations (1.65 and 16.5 microM); in contrast alpha, beta-methylene ATP and alpha, beta-methylene ADP (resistant to hydrolysis into AMP and adenosine) were ineffective. Theophylline (50 microM) a specific blocker of the adenosine receptor, suppressed the glucagon peak induced by adenosine, 2-chloroadenosine, ATP and beta, gamma-methylene ATP (1.65 microM). An inhibitor of 5' nucleotidase, alpha, beta-methylene ADP (16.5 microM), reduced the glucagon increase induced by ATP and did not affect the response to adenosine (1.65 microM). These results support the hypothesis of adenosine receptors (P1-purinoceptors) on the pancreatic glucagon secretory cells and indicate that ATP acts after hydrolysis to adenosine. PMID:6097328

  1. Adenosine: Tipping the balance towards hepatic steatosis and fibrosis

    PubMed Central

    Robson, Simon C.; Schuppan, Detlef

    2010-01-01

    Fatty liver is commonly associated with alcohol ingestion and abuse. While the molecular pathogenesis of these fatty changes is well understood, the histochemical and pharmacological mechanisms by which ethanol stimulates these molecular changes remain unknown. During ethanol metabolism, adenosine is generated by the enzyme ecto-5′-nucleotidase, and adenosine production and adenosine receptor activation are known to play critical roles in the development of hepatic fibrosis. We therefore investigated whether adenosine and its receptors play a role in the development of alcohol-induced fatty liver. WT mice fed ethanol on the Lieber-DeCarli diet developed hepatic steatosis, including increased hepatic triglyceride content, while mice lacking ecto-5-nucleotidase or adenosine A1 or A2B receptors were protected from developing fatty liver. Similar protection was also seen in WT mice treated with either an adenosine A1 or A2B receptor antagonist. Steatotic livers demonstrated increased expression of genes involved in fatty acid synthesis, which was prevented by blockade of adenosine A1 receptors, and decreased expression of genes involved in fatty acid metabolism, which was prevented by blockade of adenosine A2B receptors. In vitro studies supported roles for adenosine A1 receptors in promoting fatty acid synthesis and for A2B receptors in decreasing fatty acid metabolism. These results indicate that adenosine generated by ethanol metabolism plays an important role in ethanol-induced hepatic steatosis via both A1 and A2B receptors and suggest that targeting adenosine receptors may be effective in the prevention of alcohol-induced fatty liver. PMID:20395005

  2. Adenosine augments interleukin-10 production by microglial cells through an A2B adenosine receptor-mediated process

    PubMed Central

    Koscsó, Balázs; Csóka, Balázs; Selmeczy, Zsolt; Himer, Leonóra; Pacher, Pál; Virág, László; Haskó, György

    2011-01-01

    Microglia are activated by pathogen-associated molecular patterns and produce pro-inflammatory cytokines, such as TNF-α, IL-6, and IL-12, and the anti-inflammatory cytokine IL-10. Adenosine is an endogenous purine nucleoside and is a ligand of four G protein-coupled adenosine receptors (ARs), which are the A1AR, A2AAR, A2BAR and A3AR. ARs have been shown to suppress TNF-α production by microglia, but their role in regulating IL-10 production has not been studied. Here, we demonstrate that adenosine augments IL-10 production by activated murine microglia while suppressing the production of pro-inflammatory cytokines. Since the order of potency of selective AR agonists in inducing IL-10 production was 5′-N-ethylcarboxamidoadenosine (NECA) > N6-(3-iodobenzyl)-adenosine-5′-N-methyluronamide (IB-MECA) > 2-chloro-N6-cyclopentyladenosine (CCPA) ≥ 2-p-(2-carboxyethyl)phenethylamino-5′-N-ethyl-carboxamidoadenosine (CGS21680), and the A2BAR antagonist MRS-1754 prevented the effect of NECA, we conclude that the stimulatory effect of adenosine on IL-10 production is mediated by the A2BAR. Mechanistically, adenosine augmented IL-10 mRNA accumulation by a transcriptional process. Using mutant IL-10 promoter constructs we showed that a CREB-binding region in the promoter mediated the augmenting effect of adenosine on IL-10 transcription. Chromatin immunoprecipitation analysis demonstrated that adenosine induced CREB phosphorylation at the IL-10 promoter. Silencing CREB using lentivirally delivered shRNA blocked the enhancing effect of adenosine on IL-10 production confirming a role for CREB in mediating the stimulatory effect of adenosine on IL-10 production. In addition, adenosine augmented IL-10 production by stimulating p38 MAPK. Collectively, our results establish that A2BARs augment IL-10 production by activated murine microglia. PMID:22116830

  3. Targeting of Adenosine Receptors in Ischemia-Reperfusion Injury

    PubMed Central

    Laubach, Victor E.; French, Brent A.; Okusa, Mark D.

    2010-01-01

    Importance of the field Ischemia-reperfusion (IR) injury is a common clinical problem after transplantation as well as myocardial infarction and stroke. IR initiates an inflammatory response leading to rapid tissue damage. Adenosine, produced in response to IR, is generally considered as a protective signaling molecule and elicits its physiological responses through four distinct adenosine receptors. The short half-life, lack of specificity, and rapid metabolism limits the use of adenosine as a therapeutic agent. Thus intense research efforts have focused on the synthesis and implementation of specific adenosine receptor agonists and antagonists as potential therapeutic agents for a variety of inflammatory conditions including IR injury. Areas covered by this review This review summarizes current knowledge on IR injury with a focus on lung, heart, and kidney, and examines studies that have advanced our understanding of the role of adenosine receptors and the therapeutic potential of adenosine receptor agonists and antagonists for the prevention of IR injury. What the reader will gain The reader will gain insight into the role of adenosine receptor signaling in IR injury. Take home message No clinical therapies are currently available that specifically target IR injury; however, targeting of specific adenosine receptors may offer therapeutic strategies in this regard. PMID:21110787

  4. A(3) adenosine receptor ligands: history and perspectives.

    PubMed

    Baraldi, P G; Cacciari, B; Romagnoli, R; Merighi, S; Varani, K; Borea, P A; Spalluto, G

    2000-03-01

    Adenosine regulates many physiological functions through specific cell membrane receptors. On the basis of pharmacological studies and molecular cloning, four different adenosine receptors have been identified and classified as A(1), A(2A), A(2B), and A(3). These adenosine receptors are members of the G-protein-coupled receptor family. While adenosine A(1) and A(2A) receptor subtypes have been pharmacologically characterized through the use of selective ligands, the A(3) adenosine receptor subtype is presently under study in order to better understand its physio-pathological functions. Activation of adenosine A(3) receptors has been shown to stimulate phospholipase C and D and to inhibit adenylate cyclase. Activation of A(3) adenosine receptors also causes the release of inflammatory mediators such as histamine from mast cells. These mediators are responsible for processes such as inflammation and hypotension. It has also been suggested that the A(3) receptor plays an important role in brain ischemia, immunosuppression, and bronchospasm in several animal models. Based on these results, highly selective A(3) adenosine receptor agonists and/or antagonists have been indicated as potential drugs for the treatment of asthma and inflammation, while highly selective agonists have been shown to possess cardioprotective effects. The updated material related to this field of research has been rationalized and arranged in order to offer an overview of the topic. PMID:10723024

  5. Comorbidities in Neurology: Is adenosine the common link?

    PubMed

    Boison, Detlev; Aronica, Eleonora

    2015-10-01

    Comorbidities in Neurology represent a major conceptual and therapeutic challenge. For example, temporal lobe epilepsy (TLE) is a syndrome comprised of epileptic seizures and comorbid symptoms including memory and psychiatric impairment, depression, and sleep dysfunction. Similarly, Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are accompanied by various degrees of memory dysfunction. Patients with AD have an increased likelihood for seizures, whereas all four conditions share certain aspects of psychosis, depression, and sleep dysfunction. This remarkable overlap suggests common pathophysiological mechanisms, which include synaptic dysfunction and synaptotoxicity, as well as glial activation and astrogliosis. Astrogliosis is linked to synapse function via the tripartite synapse, but astrocytes also control the availability of gliotransmitters and adenosine. Here we will specifically focus on the 'adenosine hypothesis of comorbidities' implying that astrocyte activation, via overexpression of adenosine kinase (ADK), induces a deficiency in the homeostatic tone of adenosine. We present evidence from patient-derived samples showing astrogliosis and overexpression of ADK as common pathological hallmark of epilepsy, AD, PD, and ALS. We discuss a transgenic 'comorbidity model', in which brain-wide overexpression of ADK and resulting adenosine deficiency produces a comorbid spectrum of seizures, altered dopaminergic function, attentional impairment, and deficits in cognitive domains and sleep regulation. We conclude that dysfunction of adenosine signaling is common in neurological conditions, that adenosine dysfunction can explain co-morbid phenotypes, and that therapeutic adenosine augmentation might be effective for the treatment of comorbid symptoms in multiple neurological conditions. PMID:25979489

  6. Adenosine: Essential for life but licensed to kill

    PubMed Central

    Gama, Vivian; Deshmukh, Mohanish

    2016-01-01

    In this issue of Molecular Cell, Long et al. (Long et al., 2013) report a cell death priming mechanism activated by p53 that senses extracellular adenosine accumulated following chemotherapy or hypoxia, providing a novel connection between adenosine signaling and apoptosis. PMID:25884366

  7. Different mechanisms of extracellular adenosine accumulation by reduction of the external Ca(2+) concentration and inhibition of adenosine metabolism in spinal astrocytes.

    PubMed

    Eguchi, Ryota; Akao, Sanae; Otsuguro, Ken-ichi; Yamaguchi, Soichiro; Ito, Shigeo

    2015-05-01

    Extracellular adenosine is a neuromodulator in the central nervous system. Astrocytes mainly participate in adenosine production, and extracellular adenosine accumulates under physiological and pathophysiological conditions. Inhibition of intracellular adenosine metabolism and reduction of the external Ca(2+) concentration ([Ca(2+)]e) participate in adenosine accumulation, but the precise mechanisms remain unclear. This study investigated the mechanisms underlying extracellular adenosine accumulation in cultured rat spinal astrocytes. The combination of adenosine kinase and deaminase (ADK/ADA) inhibition and a reduced [Ca(2+)]e increased the extracellular adenosine level. ADK/ADA inhibitors increased the level of extracellular adenosine but not of adenine nucleotides, which was suppressed by inhibition of equilibrative nucleoside transporter (ENT) 2. Unlike ADK/ADA inhibition, a reduced [Ca(2+)]e increased the extracellular level not only of adenosine but also of ATP. This adenosine increase was enhanced by ENT2 inhibition, and suppressed by sodium polyoxotungstate (ecto-nucleoside triphosphate diphosphohydrolase inhibitor). Gap junction inhibitors suppressed the increases in adenosine and adenine nucleotide levels by reduction of [Ca(2+)]e. These results indicate that extracellular adenosine accumulation by ADK/ADA inhibition is due to the adenosine release via ENT2, while that by reduction of [Ca(2+)]e is due to breakdown of ATP released via gap junction hemichannels, after which ENT2 incorporates adenosine into the cells. PMID:26003082

  8. Adenosine receptors and asthma in humans.

    PubMed

    Wilson, C N

    2008-10-01

    According to an executive summary of the GINA dissemination committee report, it is now estimated that approximately 300 million people (5% of the global population or 1 in 20 persons) have asthma. Despite the scientific progress made over the past several decades toward improving our understanding of the pathophysiology of asthma, there is still a great need for improved therapies, particularly oral therapies that enhance patient compliance and that target new mechanisms of action. Adenosine is an important signalling molecule in human asthma. By acting on extracellular G-protein-coupled ARs on a number of different cell types important in the pathophysiology of human asthma, adenosine affects bronchial reactivity, inflammation and airway remodelling. Four AR subtypes (A(1), A(2a), A(2b) and A(3)) have been cloned in humans, are expressed in the lung, and are all targets for drug development for human asthma. This review summarizes what is known about these AR subtypes and their function in human asthma as well as the pros and cons of therapeutic approaches to these AR targets. A number of molecules with high affinity and high selectivity for the human AR subtypes have entered clinical trials or are poised to enter clinical trials as anti-asthma treatments. With the availability of these molecules for testing in humans, the function of ARs in human asthma, as well as the safety and efficacy of approaches to the different AR targets, can now be determined. PMID:18852693

  9. Chronic benzodiazepine treatment and cortical responses to adenosine and GABA.

    PubMed

    Mally, J; Connick, J H; Stone, T W

    1990-10-22

    The effects of chronic treatment of mice with clonazepam have been examined on the responses of neocortical slices to adenosine, 5-hydroxytryptamine (5-HT) and gamma-aminobutyric acid (GABA). Responses to these agonists were measured as changes in the depolarisation induced by N-methyl-D-aspartate (NMDA). Added to the superfusion medium diazepam blocked responses to adenosine but not 5-HT; this effect was not observed with 2-chloroadenosine or in the presence of 2-hydroxynitrobenzylthioguanosine. GABA was inactive in control slices but chronic treatment with clonazepam induced responses to GABA and enhanced responses to adenosine but not 5-HT. It is suggested that the induction of GABA responses may reflect the up-regulation of GABA receptors, but the increase of adenosine responses by clonazepam implies that there is no simple relationship between adenosine receptor binding and functional responses. PMID:1979931

  10. The Role of Adenosine Signaling in Sickle Cell Therapeutics

    PubMed Central

    Field, Joshua J.; Nathan, David G.; Linden, Joel

    2014-01-01

    Recent data suggest a role for adenosine signaling in the pathogenesis of sickle cell disease (SCD). Signaling through the adenosine A2A receptor (A2AR) has demonstrated beneficial effects in SCD. Activation of A2ARs decreases inflammation in mice and patients with SCD largely by blocking activation of invariant NKT cells. Decreased inflammation may reduce the severity of vaso-occlusive crises. In contrast, adenosine signaling through the A2B receptor (A2BR) may be detrimental for patients with SCD. Priapism and the formation of sickle erythrocytes may be a consequence of A2BR activation on corpus cavernosal cells and erythrocytes, respectively. Whether adenosine signaling predominantly occurs through A2ARs or A2BRs may depend on differing levels of adenosine and disease state (steady state versus crisis). There may be opportunities to develop novel therapeutic approaches targeting A2ARs and/or A2BRs for patients with SCD. PMID:24589267

  11. A High-Affinity Adenosine Kinase from Anopheles Gambiae

    SciTech Connect

    M Cassera; M Ho; E Merino; E Burgos; A Rinaldo-Matthis; S Almo; V Schramm

    2011-12-31

    Genome analysis revealed a mosquito orthologue of adenosine kinase in Anopheles gambiae (AgAK; the most important vector for the transmission of Plasmodium falciparum in Africa). P. falciparum are purine auxotrophs and do not express an adenosine kinase but rely on their hosts for purines. AgAK was kinetically characterized and found to have the highest affinity for adenosine (K{sub m} = 8.1 nM) of any known adenosine kinase. AgAK is specific for adenosine at the nucleoside site, but several nucleotide triphosphate phosphoryl donors are tolerated. The AgAK crystal structure with a bound bisubstrate analogue Ap{sub 4}A (2.0 {angstrom} resolution) reveals interactions for adenosine and ATP and the geometry for phosphoryl transfer. The polyphosphate charge is partly neutralized by a bound Mg{sup 2+} ion and an ion pair to a catalytic site Arg. The AgAK structure consists of a large catalytic core in a three-layer {alpha}/{beta}/{alpha} sandwich, and a small cap domain in contact with adenosine. The specificity and tight binding for adenosine arise from hydrogen bond interactions of Asn14, Leu16, Leu40, Leu133, Leu168, Phe168, and Thr171 and the backbone of Ile39 and Phe168 with the adenine ring as well as through hydrogen bond interactions between Asp18, Gly64, and Asn68 and the ribosyl 2'- and 3'-hydroxyl groups. The structure is more similar to that of human adenosine kinase (48% identical) than to that of AK from Toxoplasma gondii (31% identical). With this extraordinary affinity for AgAK, adenosine is efficiently captured and converted to AMP at near the diffusion limit, suggesting an important role for this enzyme in the maintenance of the adenine nucleotide pool. mRNA analysis verifies that AgAK transcripts are produced in the adult insects.

  12. An adenosine kinase inhibitor, ABT-702, inhibits spinal nociceptive transmission by adenosine release via equilibrative nucleoside transporters in rat.

    PubMed

    Otsuguro, Ken-ichi; Tomonari, Yuki; Otsuka, Saori; Yamaguchi, Soichiro; Kon, Yasuhiro; Ito, Shigeo

    2015-10-01

    Adenosine kinase (AK) inhibitor is a potential candidate for controlling pain, but some AK inhibitors have problems of adverse effects such as motor impairment. ABT-702, a non-nucleoside AK inhibitor, shows analgesic effect in animal models of pain. Here, we investigated the effects of ABT-702 on synaptic transmission via nociceptive and motor reflex pathways in the isolated spinal cord of neonatal rats. The release of adenosine from the spinal cord was measured by HPLC. ABT-702 inhibited slow ventral root potentials (sVRPs) in the nociceptive pathway more potently than monosynaptic reflex potentials (MSRs) in the motor reflex pathway. The inhibitory effects of ABT-702 were mimicked by exogenously applied adenosine, blocked by 8CPT (8-cyclopentyl-1,3-dipropylxanthine), an adenosine A1 receptor antagonist, and augmented by EHNA (erythro-9-(2-hydroxy-3-nonyl) adenine), an adenosine deaminase (ADA) inhibitor. Equilibrative nucleoside transporter (ENT) inhibitors reversed the effects of ABT-702, but not those of adenosine. ABT-702 released adenosine from the spinal cord, an effect that was also reversed by ENT inhibitors. The ABT-702-facilitated release of adenosine by way of ENTs inhibits nociceptive pathways more potently than motor reflex pathways in the spinal cord via activation of A1 receptors. This feature is expected to lead to good analgesic effects, but, caution may be required for the use of AK inhibitors in the case of ADA dysfunction or a combination with ENT inhibitors. PMID:26066576

  13. Chaperoning of the A1-adenosine receptor by endogenous adenosine - an extension of the retaliatory metabolite concept.

    PubMed

    Kusek, Justyna; Yang, Qiong; Witek, Martin; Gruber, Christian W; Nanoff, Christian; Freissmuth, Michael

    2015-01-01

    Cell-permeable orthosteric ligands can assist folding of G protein-coupled receptors in the endoplasmic reticulum (ER); this pharmacochaperoning translates into increased cell surface levels of receptors. Here we used a folding-defective mutant of human A1-adenosine receptor as a sensor to explore whether endogenously produced adenosine can exert a chaperoning effect. This A1-receptor-Y(288)A was retained in the ER of stably transfected human embryonic kidney 293 cells but rapidly reached the plasma membrane in cells incubated with an A1 antagonist. This was phenocopied by raising intracellular adenosine levels with a combination of inhibitors of adenosine kinase, adenosine deaminase, and the equilibrative nucleoside transporter: mature receptors with complex glycosylation accumulated at the cell surface and bound to an A1-selective antagonist with an affinity indistinguishable from the wild-type A1 receptor. The effect of the inhibitor combination was specific, because it did not result in enhanced surface levels of two folding-defective human V2-vasopressin receptor mutants, which were susceptible to pharmacochaperoning by their cognate antagonist. Raising cellular adenosine levels by subjecting cells to hypoxia (5% O2) reproduced chaperoning by the inhibitor combination and enhanced surface expression of A1-receptor-Y(288)A within 1 hour. These findings were recapitulated for the wild-type A1 receptor. Taken together, our observations document that endogenously formed adenosine can chaperone its cognate A1 receptor. This results in a positive feedback loop that has implications for the retaliatory metabolite concept of adenosine action: if chaperoning by intracellular adenosine results in elevated cell surface levels of A1 receptors, these cells will be more susceptible to extracellular adenosine and thus more likely to cope with metabolic distress. PMID:25354767

  14. Immunosuppression via adenosine receptor activation by adenosine monophosphate released from apoptotic cells

    PubMed Central

    Yamaguchi, Hiroshi; Maruyama, Toshihiko; Urade, Yoshihiro; Nagata, Shigekazu

    2014-01-01

    Apoptosis is coupled with recruitment of macrophages for engulfment of dead cells, and with compensatory proliferation of neighboring cells. Yet, this death process is silent, and it does not cause inflammation. The molecular mechanisms underlying anti-inflammatory nature of the apoptotic process remains poorly understood. In this study, we found that the culture supernatant of apoptotic cells activated the macrophages to express anti-inflammatory genes such as Nr4a and Thbs1. A high level of AMP accumulated in the apoptotic cell supernatant in a Pannexin1-dependent manner. A nucleotidase inhibitor and A2a adenosine receptor antagonist inhibited the apoptotic supernatant-induced gene expression, suggesting AMP was metabolized to adenosine by an ecto-5’-nucleotidase expressed on macrophages, to activate the macrophage A2a adenosine receptor. Intraperitoneal injection of zymosan into Adora2a- or Panx1-deficient mice produced high, sustained levels of inflammatory mediators in the peritoneal lavage. These results indicated that AMP from apoptotic cells suppresses inflammation as a ‘calm down’ signal. DOI: http://dx.doi.org/10.7554/eLife.02172.001 PMID:24668173

  15. Ethanol Tolerance Affects Endogenous Adenosine Signaling in Mouse Hippocampus.

    PubMed

    Zhang, Dali; Xiong, Wei; Jackson, Michael F; Parkinson, Fiona E

    2016-07-01

    Ethanol has many pharmacological effects, including increases in endogenous adenosine levels and adenosine receptor activity in brain. Ethanol consumption is associated with both positive and negative health outcomes, but tolerance to the behavioral effects of ethanol can lead to increased consumption, which increases the risk of negative health outcomes. The present study was performed to test whether a 7-day treatment with ethanol is linked to reduced adenosine signaling and whether this is a consequence of reduced ecto-5'-nucleotidase activity. Wild-type (CD73(+/+)) and ecto-5'-nucleotidase-deficient (CD73(-/-)) mice were treated with ethanol (2 g/kg) or saline for 7 days. In CD73(+/+) mice, repeated ethanol treatment reduced the hypothermic and ataxic effects of acute ethanol, indicating the development of tolerance to the acute effects of ethanol. In CD73(+/+) mice, this 7-day ethanol treatment led to increased hippocampal synaptic activity and reduced adenosine A1 receptor activity under both basal and low Mg(2+) conditions. These effects of ethanol tolerance were associated with an 18% decrease in activity of ecto-5'-nucleotidase activity in hippocampal cell membranes. In contrast, ethanol treatment was not associated with changes in synaptic activity or adenosine signaling in hippocampus from CD73(-/-) mice. These data indicate that ethanol treatment is associated with a reduction in adenosine signaling through adenosine A1 receptors in hippocampus, mediated, at least in part, via reduced ecto-5'-nucleotidase activity. PMID:27189965

  16. Ethanol Tolerance Affects Endogenous Adenosine Signaling in Mouse Hippocampus

    PubMed Central

    Zhang, Dali; Xiong, Wei; Jackson, Michael F.

    2016-01-01

    Ethanol has many pharmacological effects, including increases in endogenous adenosine levels and adenosine receptor activity in brain. Ethanol consumption is associated with both positive and negative health outcomes, but tolerance to the behavioral effects of ethanol can lead to increased consumption, which increases the risk of negative health outcomes. The present study was performed to test whether a 7-day treatment with ethanol is linked to reduced adenosine signaling and whether this is a consequence of reduced ecto-5′-nucleotidase activity. Wild-type (CD73+/+) and ecto-5′-nucleotidase-deficient (CD73−/−) mice were treated with ethanol (2 g/kg) or saline for 7 days. In CD73+/+ mice, repeated ethanol treatment reduced the hypothermic and ataxic effects of acute ethanol, indicating the development of tolerance to the acute effects of ethanol. In CD73+/+ mice, this 7-day ethanol treatment led to increased hippocampal synaptic activity and reduced adenosine A1 receptor activity under both basal and low Mg2+ conditions. These effects of ethanol tolerance were associated with an 18% decrease in activity of ecto-5′-nucleotidase activity in hippocampal cell membranes. In contrast, ethanol treatment was not associated with changes in synaptic activity or adenosine signaling in hippocampus from CD73−/− mice. These data indicate that ethanol treatment is associated with a reduction in adenosine signaling through adenosine A1 receptors in hippocampus, mediated, at least in part, via reduced ecto-5′-nucleotidase activity. PMID:27189965

  17. Identification of possible adenosine receptors in vascular smooth muscle

    SciTech Connect

    Doctrow, S.R.

    1985-01-01

    Adenosine is a vasodilator and has been implicated in increased blood flow in tissues that undergo energy deficiency. During conditions such as hypoxia and ischemia, adenosine is produced and is said to increase blood flow by relaxing the vascular smooth muscle (VSM) lining the resistance vessels. The goal of this research was to identify receptors that might be responsible for adenosine-mediated VSM relaxation. When an insoluble fraction from calf aortic VSM was incubated with /sup 32/P-ATP, two components were phosphorylated. One was identified as myosin light chain by MW, pl, and immunoprecipitation. The other product was identified as phosphatidylinositol-4-phosphate (DPI) by tic. Both phosphorylations were inhibited by adenosine and by 5'-chloro-5'-deoxyadenosine (Cl-Ado). DPI production was much more sensitive to the nucleosides than was myosin phosphorylation. Neither inhibition involved change in cAMP production. Phosphatidylinositol (Pl) kinase in the VSM membranes required magnesium, was activated and solubilized by Triton X-100, and phosphorylated both endogenous and exogenous Pl. Cl-Ado inhibited Pl kinase in a manner competitive with respect to ATP and noncompetitive with respect to Pl. Adenosine and adenosine analogs modified in the ribose ring were inhibitors with potencies comparable to that of Cl-Ado. Adenine nucleotides and purine-modified adenosine analogs were weaker inhibitors than Cl-Ado.

  18. Characteristic molecular vibrations of adenosine receptor ligands.

    PubMed

    Chee, Hyun Keun; Yang, Jin-San; Joung, Je-Gun; Zhang, Byoung-Tak; Oh, S June

    2015-02-13

    Although the regulation of membrane receptor activation is known to be crucial for molecular signal transduction, the molecular mechanism underlying receptor activation is not fully elucidated. Here we study the physicochemical nature of membrane receptor behavior by investigating the characteristic molecular vibrations of receptor ligands using computational chemistry and informatics methods. By using information gain, t-tests, and support vector machines, we have identified highly informative features of adenosine receptor (AdoR) ligand and corresponding functional amino acid residues such as Asn (6.55) of AdoR that has informative significance and is indispensable for ligand recognition of AdoRs. These findings may provide new perspectives and insights into the fundamental mechanism of class A G protein-coupled receptor activation. PMID:25622891

  19. Increased Cortical Extracellular Adenosine Correlates with Seizure Termination

    PubMed Central

    Van Gompel, Jamie J.; Bower, Mark R.; Worrell, Gregory A.; Stead, Matt; Chang, Su-Youne; Goerss, Stephan J.; Kim, Inyong; Bennet, Kevin E.; Meyer, Fredric B.; Marsh, W. Richard; Blaha, Charles D.; Lee, Kendall H.

    2014-01-01

    Objective Seizures are currently defined by their electrographic features. However, neuronal networks are intrinsically dependent upon neurotransmitters of which little is known regarding their peri-ictal dynamics. Evidence supports adenosine as having a prominent role in seizure termination, as its administration can terminate and reduce seizures in animal models. Further, microdialysis studies in humans suggest adenosine is elevated peri-ictally, but the relationship to the seizure is obscured by its temporal measurement limitations. Because electrochemical techniques can provide vastly superior temporal resolution, we test the hypothesis that extracellular adenosine concentrations rise during seizure termination in an animal model and humans using electrochemistry. Methods White farm swine (n=45) were used in an acute cortical model of epilepsy and 10 human epilepsy patients were studied during intraoperative electrocorticography (Ecog). Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) based fast scan cyclic voltametry (FSCV) and fixed potential amperometry were obtained utilizing an adenosine specific triangular waveform or biosensors respectively. Results Simultaneous Ecog and electrochemistry demonstrated an average adenosine rise of 260% compared to baseline at 7.5 ± 16.9 seconds with amperometry (n=75 events) and 2.6 ± 11.2 seconds with FSCV (n=15 events) prior to electrographic seizure termination. In agreement with these animal data, adenosine elevation prior to seizure termination in a human patient utilizing FSCV was also seen. Significance Simultaneous Ecog and electrochemical recording supports the hypothesis that adenosine rises prior to seizure termination, suggesting that adenosine itself may be responsible for seizure termination. Future work using intraoperative WINCS based FSCV recording may help to elucidate the precise relationship between adenosine and seizure termination. PMID:24483230

  20. Why do asthmatic subjects respond so strongly to inhaled adenosine?

    PubMed

    Meade, C J; Dumont, I; Worrall, L

    2001-08-01

    Bronchospasm induced by adenosine is blocked by representatives of all the major classes of drugs used in the treatment of asthma. Understanding the mechanism of this bronchospasm may help understand the way these drugs work. Clinical studies have suggested involvement of neural pathways, mast-like cells and mediators such as histamine, serotonin and lipoxygenase products. There is a strong link between responsiveness to adenosine and eosinophilia. In different animal models A1, A2b and A3 adenosine receptor subclasses have all been implicated in inducing bronchospasm. whilst occupation of the A2a receptor generally has no, or the opposite effect. At least two different mechanisms, both involving neural pathways, exist. One, involving the adenosine A1 receptor, functions in mast cell depleted animals; the other requires interaction with a population of mast-like cells activated over A2b or A3 receptors. Not only histamine but also serotonin and lipoxygenase products released from the mast-like cells are potential mediators. In animal models good reactivity to adenosine receptor agonists is generally only found when the animals are first sensitized and exposed to allergen in ways likely to induce an allergic inflammation. An exception is the BDE rat, which reacts to adenosine receptor agonists such as APNEA or NECA even without allergen exposure. This rat strain does however show evidence of spontaneous eosinophilic inflammation in the lung even without immunization. As mast cells both release adenosine and respond to adenosine, adenosine provides a non-specific method of amplifying specific signals resulting from IgE/antigen interaction. This mechanism may not only have a pathological significance in asthma; it may be part of a normal bodily defense response that in asthmatic subjects is inappropriately activated. PMID:11521747

  1. Adenosine reversal of in vivo hepatic responsiveness to insulin.

    PubMed

    McLane, M P; Black, P R; Law, W R; Raymond, R M

    1990-01-01

    Modulation by adenosine of hepatic responsiveness to insulin was investigated in vivo in 10 healthy mongrel dogs of both sexes by determining net hepatic glucose output (NHGO) in response to insulin during the presence or absence of exogenous adenosine infusion. In addition, two separate series of experiments were performed to study the effect of adenosine (n = 7) or glucagon (n = 5) on NHGO. Basal NHGO, quantitated via the Fick principle, was significantly decreased by insulin infusion (4 U/min; 4.8 +/- 0.6 vs. -1.7 +/- 2.6 mg.kg-1.min-1, P less than 0.05). The addition of an intrahepatic arterial infusion of adenosine (10 mumol/min) during insulin infusion caused glucose output to return to basal levels (insulin, -1.7 +/- 2.6 mg.kg-1.min-1; insulin + adenosine, 3.8 +/- 1.6 mg.kg-1.min-1, P less than 0.05). The addition of intrahepatic arterial saline (control) during insulin infusion had no effect on insulin's action (insulin, -1.0 +/- 1.9 mg.kg-1.min-1; insulin + saline, -1.2 +/- 1.6 mg.kg-1.min-1, P greater than 0.05). Hepatic glucose, lactate, and oxygen deliveries were not affected during either insulin or insulin plus adenosine infusion. Intrahepatic arterial infusion of adenosine alone had no effect on NHGO, whereas intrahepatic arterial infusion of glucagon alone stimulated glucose output approximately fivefold (basal, 2.7 +/- 0.4 mg.kg-1.min-1; glucagon, 15.5 +/- 1.2 mg.kg-1.min-1, P less than 0.01). These results show that adenosine completely reversed the inhibition by insulin of NHGO. These data suggest that adenosine may act as a modulator of insulin action on the liver. PMID:2210062

  2. Adenosine deaminase in disorders of purine metabolism and in immune deficiency

    SciTech Connect

    Tritsch, G.L.

    1985-01-01

    This book consists of five parts and a section of poster papers. Some of the selection titles are: Adenosine Deaminase Impairment and Ribonucleotide Reductase in Human Cells; Adenosine Deaminase and Malignant Cells; Inhibition of Adenosine Deaminase to Increase the Antitumor Activity of Adenine Nucleoside Analogues; and Molecular Biology of the Adenosine Deaminase Gene and Messenger RNA.

  3. Excess adenosine in murine penile erectile tissues contributes to priapism via A2B adenosine receptor signaling

    PubMed Central

    Mi, Tiejuan; Abbasi, Shahrzad; Zhang, Hong; Uray, Karen; Chunn, Janci L.; Xia, Ling Wei; Molina, Jose G.; Weisbrodt, Norman W.; Kellems, Rodney E.; Blackburn, Michael R.; Xia, Yang

    2008-01-01

    Priapism, abnormally prolonged penile erection in the absence of sexual excitation, is associated with ischemia-mediated erectile tissue damage and subsequent erectile dysfunction. It is common among males with sickle cell disease (SCD), and SCD transgenic mice are an accepted model of the disorder. Current strategies to manage priapism suffer from a poor fundamental understanding of the molecular mechanisms underlying the disorder. Here we report that mice lacking adenosine deaminase (ADA), an enzyme necessary for the breakdown of adenosine, displayed unexpected priapic activity. ADA enzyme therapy successfully corrected the priapic activity both in vivo and in vitro, suggesting that it was dependent on elevated adenosine levels. Further genetic and pharmacologic evidence demonstrated that A2B adenosine receptor–mediated (A2BR-mediated) cAMP and cGMP induction was required for elevated adenosine–induced prolonged penile erection. Finally, priapic activity in SCD transgenic mice was also caused by elevated adenosine levels and A2BR activation. Thus, we have shown that excessive adenosine accumulation in the penis contributes to priapism through increased A2BR signaling in both Ada–/– and SCD transgenic mice. These findings provide insight regarding the molecular basis of priapism and suggest that strategies to either reduce adenosine or block A2BR activation may prove beneficial in the treatment of this disorder. PMID:18340377

  4. Extracellular Adenosine Mediates a Systemic Metabolic Switch during Immune Response

    PubMed Central

    Bajgar, Adam; Kucerova, Katerina; Jonatova, Lucie; Tomcala, Ales; Schneedorferova, Ivana; Okrouhlik, Jan; Dolezal, Tomas

    2015-01-01

    Immune defense is energetically costly, and thus an effective response requires metabolic adaptation of the organism to reallocate energy from storage, growth, and development towards the immune system. We employ the natural infection of Drosophila with a parasitoid wasp to study energy regulation during immune response. To combat the invasion, the host must produce specialized immune cells (lamellocytes) that destroy the parasitoid egg. We show that a significant portion of nutrients are allocated to differentiating lamellocytes when they would otherwise be used for development. This systemic metabolic switch is mediated by extracellular adenosine released from immune cells. The switch is crucial for an effective immune response. Preventing adenosine transport from immune cells or blocking adenosine receptor precludes the metabolic switch and the deceleration of development, dramatically reducing host resistance. Adenosine thus serves as a signal that the “selfish” immune cells send during infection to secure more energy at the expense of other tissues. PMID:25915062

  5. Alterations of adenosine A1 receptors in morphine dependence.

    PubMed

    Kaplan, G B; Leite-Morris, K A; Sears, M T

    1994-09-19

    The possibility that central adenosine A1 and A2a receptors mediate opiate dependence was examined in morphine-treated mice using radioligand binding methods. Mice treated with morphine for 72 h demonstrated significant increases in naloxone precipitated abstinence behaviors of jumping, wet-dog shakes, teeth chattering, forepaw trends, forepaw tremors and diarrhea compared to vehicle-treated mice. Increased concentrations of cortical adenosine A1 receptor sites, but not striatal adenosine A2a sites, were found in saturation binding studies from morphine-dependent mice. Decreases in cortical A1 agonist binding affinity values along with increases in agonist binding sites were demonstrated in competition binding studies. These results suggest that adaptive changes of upregulation and sensitization of adenosine A1 receptors play a role in mediating the opiate abstinence syndrome. PMID:7820640

  6. Proton transfer in oxidized adenosine self-aggregates.

    PubMed

    Capobianco, Amedeo; Caruso, Tonino; Celentano, Maurizio; La Rocca, Mario Vincenzo; Peluso, Andrea

    2013-10-14

    The UV-vis and the IR spectra of derivativized adenosine in dichloromethane have been recorded during potentiostatic oxidation at an optically transparent thin layer electrode. Oxidized adenosine shows a broad Zundel like absorption extending from 2800 up to 3600 cm(-1), indicating that a proton transfer process is occurring. Theoretical computations predict that proton transfer is indeed favored in oxidized 1:1 self-association complexes and allow to assign all the observed transient spectroscopic signals. PMID:24116647

  7. The A3 adenosine receptor: history and perspectives.

    PubMed

    Borea, Pier Andrea; Varani, Katia; Vincenzi, Fabrizio; Baraldi, Pier Giovanni; Tabrizi, Mojgan Aghazadeh; Merighi, Stefania; Gessi, Stefania

    2015-01-01

    By general consensus, the omnipresent purine nucleoside adenosine is considered a major regulator of local tissue function, especially when energy supply fails to meet cellular energy demand. Adenosine mediation involves activation of a family of four G protein-coupled adenosine receptors (ARs): A(1), A(2)A, A(2)B, and A(3). The A(3) adenosine receptor (A(3)AR) is the only adenosine subtype to be overexpressed in inflammatory and cancer cells, thus making it a potential target for therapy. Originally isolated as an orphan receptor, A(3)AR presented a twofold nature under different pathophysiologic conditions: it appeared to be protective/harmful under ischemic conditions, pro/anti-inflammatory, and pro/antitumoral depending on the systems investigated. Until recently, the greatest and most intriguing challenge has been to understand whether, and in which cases, selective A(3) agonists or antagonists would be the best choice. Today, the choice has been made and A(3)AR agonists are now under clinical development for some disorders including rheumatoid arthritis, psoriasis, glaucoma, and hepatocellular carcinoma. More specifically, the interest and relevance of these new agents derives from clinical data demonstrating that A(3)AR agonists are both effective and safe. Thus, it will become apparent in the present review that purine scientists do seem to be getting closer to their goal: the incorporation of adenosine ligands into drugs with the ability to save lives and improve human health. PMID:25387804

  8. Detrimental effects of adenosine signaling in sickle cell disease

    PubMed Central

    Zhang, Yujin; Dai, Yingbo; Wen, Jiaming; Zhang, Weiru; Grenz, Almut; Sun, Hong; Tao, Lijian; Lu, Guangxiu; Alexander, Danny C; Milburn, Michael V; Carter-Dawson, Louvenia; Lewis, Dorothy E; Zhang, Wenzheng; Eltzschig, Holger K; Kellems, Rodney E; Blackburn, Michael R; Juneja, Harinder S; Xia, Yang

    2016-01-01

    Hypoxia can act as an initial trigger to induce erythrocyte sickling and eventual end organ damage in sickle cell disease (SCD). Many factors and metabolites are altered in response to hypoxia and may contribute to the pathogenesis of the disease. Using metabolomic profiling, we found that the steady-state concentration of adenosine in the blood was elevated in a transgenic mouse model of SCD. Adenosine concentrations were similarly elevated in the blood of humans with SCD. Increased adenosine levels promoted sickling, hemolysis and damage to multiple tissues in SCD transgenic mice and promoted sickling of human erythrocytes. Using biochemical, genetic and pharmacological approaches, we showed that adenosine A2B receptor (A2BR)-mediated induction of 2,3-diphosphoglycerate, an erythrocyte-specific metabolite that decreases the oxygen binding affinity of hemoglobin, underlies the induction of erythrocyte sickling by excess adenosine both in cultured human red blood cells and in SCD transgenic mice. Thus, excessive adenosine signaling through the A2BR has a pathological role in SCD. These findings may provide new therapeutic possibilities for this disease. PMID:21170046

  9. Myocardial perfusion scintigraphy during maximal coronary artery vasodilation with adenosine

    SciTech Connect

    Verani, M.S.; Mahmarian, J.J. )

    1991-05-21

    Pharmacologic coronary vasodilation as an adjunct to thallium-201 myocardial perfusion scintigraphy provides an important alternative form of stress that has been increasingly used in patients unable to perform an exercise stress test. Although dipyridamole has traditionally been used for this purpose, there are several compelling reasons why adenosine may be a preferable agent. First, dipyridamole acts by blocking the reuptake and transport of adenosine, which is the effective substance responsible for coronary vasodilation. Second, exogenous adenosine has a very short half-life (less than 2 seconds), which explains its very short duration of action as well as the brief, self-limiting duration of its side effects. Third, the adenosine infusion is controllable and may be increased or decreased as desired. Fourth, the coronary vasodilation induced by the doses of adenosine we recommend (140 micrograms/kg/min) may be more profound than that induced by the standard dipyridamole dose. Our experience to date, with nearly 1,000 patients studied, shows the adenosine thallium-201 test to be practical and well tolerated, with high sensitivity (87%) and specificity (94%) for detecting coronary artery disease.

  10. Adenosine deaminase inhibition enhances the inotropic response mediated by A1 adenosine receptor in hyperthyroid guinea pig atrium.

    PubMed

    Kemeny-Beke, Adam; Jakab, Anita; Zsuga, Judit; Vecsernyes, Miklos; Karsai, Denes; Pasztor, Fanni; Grenczer, Maria; Szentmiklosi, Andras Jozsef; Berta, Andras; Gesztelyi, Rudolf

    2007-08-01

    The aim of the present study was to test the hypothesis that inhibition of adenosine deaminase (ADA) enhances the efficiency of signal-transduction of myocardial A1 adenosine receptors in hyperthyroidism. The inotropic response to N6-cyclopentyladenosine (CPA), a selective A1 adenosine receptor agonist resistant to ADA, was investigated in the absence or presence of erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an ADA and cGMP-stimulated 3',5'-cyclic nucleotide phosphodiesterase (PDE2) inhibitor, or of pentostatin (2'-deoxycoformycin; DCF), an exclusive ADA inhibitor, in left atria isolated from eu- or hyperthyroid guinea pigs. Both ADA inhibitors enhanced the effect of CPA only in hyperthyroid atria. EHNA significantly increased the Emax (mean+/-S.E.M.) from 83.8+/-1.2% to 93.4+/-1.2%, while DCF significantly decreased the logEC50 from -7.5+/-0.07 to -7.83+/-0.07 in hyperthyroid samples. Conversely, EHNA also diminished the logEC50 (from -7.5+/-0.07 to -7.65+/-0.07) and DCF also raised the Emax (from 83.8+/-1.2% to 85.7+/-2%) in hyperthyroidism, but these changes were not significant. In conclusion, ADA inhibition moderately but significantly enhanced the efficiency of A(1) adenosine receptor signaling pathway in the hyperthyroid guinea pig atrium. This suggests that elevated intracellular adenosine level caused by ADA inhibition may improve the suppressed responsiveness to A1 adenosine receptor agonists associated with the hyperthyroid state. Alternatively or in addition, the role of decreased concentration of adenosine degradation products cannot be excluded. Furthermore, in the case of EHNA, inhibition of PDE2 also appears to contribute to the enhanced A1 adenosine receptor signaling in the hyperthyroid guinea pig atrium. PMID:17574432

  11. Interstitial adenosine concentration is increased by dipyridamole

    SciTech Connect

    Gorman, M.W.; Wangler, R.D.; DeWitt, D.F.; Wang, C.Y.; Bassingthwaighte, J.B.; Sparks, H.V.

    1986-03-01

    The authors used the multiple indicator dilution technique to observe the capillary transport of adenosine (ADO) in isolated guinea pig hearts. Radiolabelled albumin, sucrose and ADO were injected on the arterial side and measured in venous samples collected during the following 20 seconds. Transport parameters calculated from these data include permeability-surface area products (PS) for transendothelial diffusion, endothelial cell (EC) uptake at the lumenal and ablumenal membranes, and EC metabolism. With simultaneous measurements of arterial and venous ADO concentrations and flow, the authors calculated the steady-state interstitial fluid (ISF) ADO concentration. Under control conditions the venous ADO concentration was 7.1 +/- 2.8 nM. The calculated ISF concentration depends on whether they assume the venous ADO comes from the ISF, or directly from ECs. These ISF concentrations are 25 +/- 12 nM and 9.8 +/- 4.0 nM, respectively. During dipyridamole infusion (10 uM) the EC transport parameters became nearly zero. Venous and ISF ADO concentrations increased to 33 +/- 8.9 nM and 169 +/- 42 nM, respectively. The authors conclude that the ISF ADO concentration is 1.5-4 fold higher than the venous concentration at rest, and the ISF concentration increases greatly with dipyridamole.

  12. Role of A3 adenosine receptor in diabetic neuropathy.

    PubMed

    Yan, Heng; Zhang, Enshui; Feng, Chang; Zhao, Xin

    2016-10-01

    Neuropathy is the most common diabetic complication. Although the A1 and A2A adenosine receptors are important pharmacological targets in alleviating diabetic neuropathy, the role of the A3 adenosine receptor remains unknown. Because the A3 adenosine receptor regulates pain induced by chronic constriction injury or chemotherapy, its stimulation might also attenuate diabetic neuropathy. This study examines the effects of systemic treatment with the A3 adenosine receptor agonist 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA) on diabetic neuropathy and explores the putative mechanisms underlying its pharmacological effects. We show that IB-MECA alleviated mechanical hyperalgesia and thermal hypoalgesia in mice 2 weeks but not 4 weeks after streptozocin (STZ) treatment. Furthermore, IB-MECA prevented the reduction in sciatic motor nerve conduction velocity and sensory nerve conduction velocity in diabetic mice 2 weeks but not 4 weeks after STZ treatment. Similarly, IB-MECA inhibited the activation of nuclear factor-κB and decreased the generation of tumor necrosis factor-α in the spinal cord of mice 2 weeks but not 4 weeks after STZ treatment. These phenomena were associated with reduction of A3 adenosine receptor expression in the spinal cord after long-term diabetes. Our results suggest that the A3 adenosine receptor plays a critical role in regulating diabetic neuropathy and that reduction in A3 adenosine receptor expression/function might contribute to the progression of diabetic neuropathy. © 2016 Wiley Periodicals, Inc. PMID:27319979

  13. Adenosine deaminase from Streptomyces coelicolor: recombinant expression, purification and characterization.

    PubMed

    Pornbanlualap, Somchai; Chalopagorn, Pornchanok

    2011-08-01

    The sequencing of the genome of Streptomyces coelicolor A3(2) identified seven putative adenine/adenosine deaminases and adenosine deaminase-like proteins, none of which have been biochemically characterized. This report describes recombinant expression, purification and characterization of SCO4901 which had been annotated in data bases as a putative adenosine deaminase. The purified putative adenosine deaminase gives a subunit Mr=48,400 on denaturing gel electrophoresis and an oligomer molecular weight of approximately 182,000 by comparative gel filtration. These values are consistent with the active enzyme being composed of four subunits with identical molecular weights. The turnover rate of adenosine is 11.5 s⁻¹ at 30 °C. Since adenine is deaminated ∼10³ slower by the enzyme when compared to that of adenosine, these data strongly show that the purified enzyme is an adenosine deaminase (ADA) and not an adenine deaminase (ADE). Other adenine nucleosides/nucleotides, including 9-β-D-arabinofuranosyl-adenine (ara-A), 5'-AMP, 5'-ADP and 5'-ATP, are not substrates for the enzyme. Coformycin and 2'-deoxycoformycin are potent competitive inhibitors of the enzyme with inhibition constants of 0.25 and 3.4 nM, respectively. Amino acid sequence alignment of ScADA with ADAs from other organisms reveals that eight of the nine highly conserved catalytic site residues in other ADAs are also conserved in ScADA. The only non-conserved residue is Asn317, which replaces Asp296 in the murine enzyme. Based on these data, it is suggested here that ADA and ADE proteins are divergently related enzymes that have evolved from a common α/β barrel scaffold to catalyze the deamination of different substrates, using a similar catalytic mechanism. PMID:21511036

  14. Increased adenosine contributes to penile fibrosis, a dangerous feature of priapism, via A2B adenosine receptor signaling

    PubMed Central

    Wen, Jiaming; Jiang, Xianzhen; Dai, Yingbo; Zhang, Yujin; Tang, Yuxin; Sun, Hong; Mi, Tiejuan; Phatarpekar, Prasad V.; Kellems, Rodney E.; Blackburn, Michael R.; Xia, Yang

    2010-01-01

    Priapism is a condition of persistent penile erection in the absence of sexual excitation. Of men with sickle cell disease (SCD), 40% display priapism. The disorder is a dangerous and urgent condition, given its association with penile fibrosis and eventual erectile dysfunction. Current strategies to prevent its progression are poor because of a lack of fundamental understanding of the molecular mechanisms for penile fibrosis in priapism. Here we demonstrate that increased adenosine is a novel causative factor contributing to penile fibrosis in two independent animal models of priapism, adenosine deaminase (ADA)-deficient mice and SCD transgenic mice. An important finding is that chronic reduction of adenosine by ADA enzyme therapy successfully attenuated penile fibrosis in both mouse models, indicating an essential role of increased adenosine in penile fibrosis and a novel therapeutic possibility for this serious complication. Subsequently, we identified that both mice models share a similar fibrotic gene expression profile in penile tissue (including procollagen I, TGF-β1, and plasminogen activator inhibitor-1 mRNA), suggesting that they share similar signaling pathways for progression to penile fibrosis. Thus, in an effort to decipher specific cell types and underlying mechanism responsible for adenosine-mediated penile fibrosis, we purified corpus cavernosal fibroblast cells (CCFCs), the major cell type involved in this process, from wild-type mice. Quantitative RT-PCR showed that the major receptor expressed in these cells is the adenosine receptor A2BR. Based on this fact, we further purified CCFCs from A2BR-deficient mice and demonstrated that A2BR is essential for excess adenosine-mediated penile fibrosis. Finally, we revealed that TGF-β functions downstream of the A2BR to increase CCFC collagen secretion and proliferation. Overall, our studies identify an essential role of increased adenosine in the pathogenesis of penile fibrosis via A2BR signaling and

  15. Effect of adenosine on the growth of human T-lymphocyte leukemia cell line MOLT-4.

    PubMed

    Streitová, Denisa; Weiterová, Lenka; Hofer, Michal; Holá, Jirina; Horváth, Viktor; Kozubík, Alois; Znojil, Vladimír

    2007-09-01

    Adenosine has been observed to suppress the growth of MOLT-4 human leukemia cells in vitro. Changes in the cell cycle, especially increased percentage of cells in S phase, prolonged generation time, and induction of apoptosis at higher adenosine concentrations have been found to be responsible for the growth suppression. Dipyridamole, a drug inhibiting the cellular uptake of adenosine, reversed partially but significantly the adenosine-induced growth suppression. It follows from these results that the action of adenosine on the MOLT-4 cells comprises its cellular uptake and intracellular operation. These findings present new data on anticancer efficacy of adenosine. PMID:17882653

  16. Tween 20-stabilized gold nanoparticles combined with adenosine triphosphate-BODIPY conjugates for the fluorescence detection of adenosine with more than 1000-fold selectivity.

    PubMed

    Hung, Szu-Ying; Shih, Ya-Chen; Tseng, Wei-Lung

    2015-02-01

    This study describes the development of a simple, enzyme-free, label-free, sensitive, and selective system for detecting adenosine based on the use of Tween 20-stabilized gold nanoparticles (Tween 20-AuNPs) as an efficient fluorescence quencher for boron dipyrromethene-conjugated adenosine 5'-triphosphate (BODIPY-ATP) and as a recognition element for adenosine. BODIPY-ATP can interact with Tween 20-AuNPs through the coordination between the adenine group of BODIPY-ATP and Au atoms on the NP surface, thereby causing the fluorescence quenching of BODIPY-ATP through the nanometal surface energy transfer (NSET) effect. When adenosine attaches to the NP surface, the attached adenosine exhibits additional electrostatic attraction to BODIPY-ATP. As a result, the presence of adenosine enhances the efficiency of AuNPs in fluorescence quenching of BODIPY-ATP. The AuNP-induced fluorescence quenching of BODIPY-ATP progressively increased with an increase in the concentration of adenosine; the detection limit at a signal-to-noise ratio of 3 for adenosine was determined to be 60nM. The selectivity of the proposed system was more than 1000-fold for adenosine over any adenosine analogs and other nucleotides. The proposed system combined with a phenylboronic acid-containing column was successfully applied to the determination of adenosine in urine. PMID:25604821

  17. Adenosine signaling and the regulation of chronic lung disease

    PubMed Central

    Zhou, Yang; Schneider, Daniel J.; Blackburn, Michael R.

    2009-01-01

    Chronic lung diseases such as asthma, chronic obstructive pulmonary disease and interstitial lung disease are characterized by inflammation and tissue remodeling processes that compromise pulmonary function. Adenosine is produced in the inflamed and damaged lung where it plays numerous roles in the regulation of inflammation and tissue remodeling. Extracellular adenosine serves as an autocrine and paracrine signaling molecule by engaging cell surface adenosine receptors. Preclinical and cellular studies suggest that adenosine plays an anti-inflammatory role in processes associated with acute lung disease, where activation of the A2AR and A2BR have promising implications for the treatment of these disorders. In contrast, there is growing evidence that adenosine signaling through the A1R, A2BR and A3R may serve pro-inflammatory and tissue remodeling functions in chronic lung diseases. This review discusses the current progress of research efforts and clinical trials aimed at understanding the complexities of this signaling pathway as they pertain to the development of treatment strategies for chronic lung diseases. PMID:19426761

  18. Dicinnamoylquinides in roasted coffee inhibit the human adenosine transporter.

    PubMed

    de Paulis, Tomas; Schmidt, Dennis E; Bruchey, Aleksandra K; Kirby, Michael T; McDonald, Michael P; Commers, Patricia; Lovinger, David M; Martin, Peter R

    2002-05-10

    Preliminary screening of a minor, non-xanthine constituent of roasted coffee, 3,4-diferuloyl-1,5-quinolactone (DIFEQ), showed inhibition of the adenosine transporter at low micromolar concentration. DIFEQ is a neutral derivative of the chlorogenic acids, i.e. isomeric mono- and di-substituted coumaroyl-, caffeoyl-, and feruloyl-esters of quinic acid, formed in the roasting process of coffee. Displacement of the adenosine transporter antagonist [(3)H](S)-(nitrobenzyl)-6-thioinosine binding by DIFEQ in cultured U-937 cell preparations, expressing the human adenosine transporter protein (hENT1), showed a K(i) of 0.96+/-0.13 microM. Extracts of regular and decaffeinated coffee showed binding activities equivalent to 30-40 mg DIFEQ per three cups of coffee. Acute administration of a high dose of DIFEQ (100 mg/kg i.p.) reduced open field locomotion in mice for 20 min in correlation with brain levels of DIFEQ. Both 3,4-dicaffeoyl-1,5-quinide and 3,4-dicoumaroyl-1,5-quinide, two close structural analogs of DIFEQ also present in roasted coffee, showed similar affinities for the adenosine transporter, while the corresponding 3- and 4-mono caffeoyl- and feruloyl-quinides were one to two orders of magnitudes less active. This suggests that 3,4-dicinnamoyl-1,5-quinides in coffee could have the potential to raise extra-cellular adenosine levels, thereby counteracting the stimulant effect of caffeine. PMID:12065074

  19. Regulation of Adenosine Deaminase on Induced Mouse Experimental Autoimmune Uveitis.

    PubMed

    Liang, Dongchun; Zuo, Aijun; Zhao, Ronglan; Shao, Hui; Kaplan, Henry J; Sun, Deming

    2016-03-15

    Adenosine is an important regulator of the immune response, and adenosine deaminase (ADA) inhibits this regulatory effect by converting adenosine into functionally inactive molecules. Studies showed that adenosine receptor agonists can be anti- or proinflammatory. Clarification of the mechanisms that cause these opposing effects should provide a better guide for therapeutic intervention. In this study, we investigated the effect of ADA on the development of experimental autoimmune uveitis (EAU) induced by immunizing EAU-prone mice with a known uveitogenic peptide, IRBP1-20. Our results showed that the effective time to administer a single dose of ADA to suppress induction of EAU was 8-14 d postimmunization, shortly before EAU expression; however, ADA treatment at other time points exacerbated disease. ADA preferentially inhibited Th17 responses, and this effect was γδ T cell dependent. Our results demonstrated that the existing immune status strongly influences the anti- or proinflammatory effects of ADA. Our observations should help to improve the design of ADA- and adenosine receptor-targeted therapies. PMID:26856700

  20. Unpredictable Chronic Stress Alters Adenosine Metabolism in Zebrafish Brain.

    PubMed

    Zimmermann, F F; Altenhofen, S; Kist, L W; Leite, C E; Bogo, M R; Cognato, G P; Bonan, C D

    2016-05-01

    Stress is considered a risk factor for several human disorders. Despite the broad knowledge of stress responses in mammals, data on the relationship between unpredictable chronic stress (UCS) and its effects on purinergic signaling are limited. ATP hydrolysis by ectonucleotidases is an important source of adenosine, and adenosine deaminase (ADA) contributes to the control of the nucleoside concentrations. Considering that some stress models could affect signaling systems, the objective of this study was to investigate whether UCS alters ectonucleotidase and ADA pathway in zebrafish brain. Additionally, we analyzed ATP metabolism as well as ada1, ada2.1, ada2.2, adaL, and adaasi gene expression in zebrafish brain. Our results have demonstrated that UCS did not alter ectonucleotidase and soluble ADA activities. However, ecto-ADA activity was significantly decreased (26.8%) in brain membranes of animals exposed to UCS when compared to the control group. Quantitative reverse transcription PCR (RT-PCR) analysis did not show significant changes on ADA gene expression after the UCS exposure. The brain ATP metabolism showed a marked increase in adenosine levels (ADO) in animals exposed to UCS. These data suggest an increase on extracellular adenosine levels in zebrafish brain. Since this nucleoside has neuromodulatory and anxiolytic effects, changes in adenosine levels could play a role in counteracting the stress, which could be related to a compensatory mechanism in order to restore the homeostasis. PMID:26081145

  1. Antagonism by theophylline of respiratory inhibition induced by adenosine.

    PubMed

    Eldridge, F L; Millhorn, D E; Kiley, J P

    1985-11-01

    The effects on respiration of an analogue of adenosine, L-2-N6-(phenylisopropyl)adenosine (PIA), and of the methylxanthine, theophylline, were determined in 19 vagotomized glomectomized cats whose end-tidal PCO2 was kept constant by means of a servo-controlled ventilator. Integrated phrenic nerve activity was used to represent respiratory output. Our results show that PIA, whether given systemically or into the third cerebral ventricle, depressed respiration. Systemically administered theophylline stimulated respiration. Theophylline given intravenously, or into the third ventricle not only reversed the depressive effects of previously administered PIA but caused further increases of respiration above the control level. Prior systemic administration of theophylline blocked both respiratory and hypotensive effects of subsequently administered PIA. Effects of either agent on medullary extracellular fluid pH did not explain the results. We conclude that the adenosine analogue PIA, acts to inhibit neurons in the brain that are involved in the control of respiration and that its effects are blocked by theophylline. We suggest that adenosine acts as a tonic modulator of respiration and that theophylline stimulates breathing by competitive antagonism of adenosine at neuronal receptor sites. PMID:4066573

  2. Prehospital use of adenosine by ambulance services in the Netherlands

    PubMed Central

    Adams, R.; Bon, V.

    2003-01-01

    Background The prehospital use of adenosine in the treatment of supraventricular arrhythmias has recently been implemented in standard ambulance care. However, establishing the origin and nature of the arrhythmia with certainty is an absolute requirement for using adenosine. Methods The ability of the ambulance nurse to predict supraventricular arrhythmias and the necessity of prehospital treatment of arrhythmias in general was evaluated. To do this, cardiologists at the Academic Medical Centre of Amsterdam were consulted and a literature search by means of an electronic search in Pubmed was performed. The search was complemented by a second survey concerning antagonists of adenosine using the keywords: adenosine and theophylline. Moreover, the Ambulance Nurse textbook, the National Protocol for Ambulance Care as well as the explanatory memorandum to the protocol were consulted. Results No strong indication for the prehospital use of adenosine was found, while detrimental effects of the drug can occur. There is no literature showing the ability of ambulance staff to correctly interpret complex cardiac arrhythmias in the Netherlands; the current ambulance protocol does not prevent an incorrect choice of therapy and medication. Conclusion It is strongly advised against using antiarrhythmic medication for the treatment of tachycardias in a prehospital setting if this treatment can be postponed to the hospital environment. PMID:25696211

  3. Ion-dependent conformational switching by a DNA aptamer that induces remyelination in a mouse model of multiple sclerosis

    PubMed Central

    Smestad, John; Maher, L. James

    2013-01-01

    We recently reported that a guanosine-rich 40-mer DNA aptamer (LJM-3064) mediates remyelination in the Theiler’s murine encephalomyelitis virus mouse model of multiple sclerosis. Here, we characterize the G-quadruplex forms of this aptamer in vitro, and demonstrate using circular dichroism spectroscopy that LJM-3064 undergoes a monovalent ion-dependent conformational switch. In the presence of sodium ions and no potassium ions, LJM-3064 adopts an antiparallel-stranded G-quadruplex structure. When presented with low concentrations of potassium ions in a buffer that mimics the composition of interstitial fluid and blood plasma, LJM-3064 rapidly switches to a parallel-stranded G-quadruplex conformation, which is presumably the physiologically active folded form. We characterize these conformational states using dimethyl sulfate reactivity studies and Bal 31 nuclease probing. Our analysis indicates that only the 5′-terminal 26 nucleotides are involved in G-quadruplex formation. Thermodynamic characterization of LJM-3064 at physiologically relevant ion concentrations reveals the G-quadruplex to be metastable at human body temperature. These data provide important structural and thermodynamic insights that may be valuable in optimizing LJM-3064 as a therapeutic remyelinating agent. PMID:23175609

  4. Adenosine deaminase--the non-invasive marker of tuberculosis.

    PubMed

    Pal, Shyamali; Gupta, Sanjoy

    2012-01-01

    Pulmonary tuberculosis is the India's biggest health problem especially in rural areas. A quick and dependable investigation is absolutely essential. Adenosine deaminase was estimated from the biological fluids (ascitic/pleural/CSF) with the help of the kit obtained from Tulip India Pvt Ltd. The method is based on the principle of Galati & Giusti colorimetric method. The method is simple, inexpensive and results are also reproducible. Elevation of adenosine deaminase has shown high specificity in all biological fluids. As the estimation principle is based on synthesis of ammonia so there is limitation of the procedure when the site is kidney. Similarly if the site is skin, as fluid cannot be collected from the site, adenosine deaminase estimation is also not possible. PMID:23029824

  5. Current status of A1 adenosine receptor allosteric enhancers.

    PubMed

    Romagnoli, Romeo; Baraldi, Pier Giovanni; Moorman, Allan R; Borea, Pier Andrea; Varani, Katia

    2015-01-01

    Adenosine is an ubiquitous nucleoside involved in various physiological and pathological functions by stimulating A1, A2A, A2B and A3 adenosine receptors (ARs). Allosteric enhancers to A1ARs may represent novel therapeutic agents because they increase the activity of these receptors by mediating a shift to their active form in the A1AR-G protein ternary complex. In this manner, they are able to amplify the action of endogenous adenosine, which is produced in high concentrations under conditions of metabolic stress. A1AR allosteric enhancers could be used as a justifiable alternative to the exogenous agonists that are characterized by receptor desensitization and downregulation. In this review, an analysis of some of the most interesting allosteric modulators of A1ARs has been reported. PMID:26144263

  6. Stability of Diluted Adenosine Solutions in Polyolefin Infusion Bags

    PubMed Central

    Almagambetova, Elise; Hutchinson, David; Blais, Danielle M.; Zhao, Fang

    2013-01-01

    Background: Intravenous or intracoronary adenosine is used in the cardiac catherization lab to achieve maximal coronary blood flow and determine fractional flow reserve. Objective: To determine the stability of adenosine 10 and 50 µg/mL in either 0.9% sodium chloride injection or 5% dextrose injection in polyolefin infusion bags stored at 2 temperatures, refrigeration (2°C-8°C) or controlled room temperature (20°C-25°C). Methods: Adenosine 10 µg/mL and 50 µg/mL solutions were prepared in 50 mL polyolefin infusion bags containing 0.9% sodium chloride injection or 5% dextrose injection and stored at controlled room temperature or under refrigeration. Each combination of concentration, diluent, and storage was prepared in triplicate. Samples were assayed using stability-indicating, reversed-phase high-performance liquid chromatography immediately at time 0 and at 24 hours, 48 hours, 7 days, and 14 days. Stability was defined as retaining 90% to 110% of the initial adenosine concentration. The samples were also visually inspected against a light background for clarity, color, and the presence of particulate matter. Results: After 14 days, all samples retained 99% to 101% of the initial adenosine concentration. No considerable change in pH or visual appearance was noted. The stability data indicated no significant loss of drug due to chemical degradation or physical interactions during storage. Conclusion: Adenosine solutions of 10 and 50 µg/mL were stable for at least 14 days in 50 mL polyolefin infusion bags of 0.9% sodium chloride injection or 5% dextrose injection stored at controlled room temperature and refrigerated conditions. PMID:24421510

  7. Investigating real-time activation of adenosine receptors by bioluminescence resonance energy transfer technique

    NASA Astrophysics Data System (ADS)

    Huang, Yimei; Yang, Hongqin; Zheng, Liqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen

    2013-02-01

    Adenosine receptors play important roles in many physiological and pathological processes, for example regulating myocardial oxygen consumption and the release of neurotransmitters. The activations of adenosine receptors have been studied by some kinds of techniques, such as western blot, immunohistochemistry, etc. However, these techniques cannot reveal the dynamical response of adenosine receptors under stimulation. In this paper, bioluminescence resonance energy transfer technique was introduced to study the real-time activation of adenosine receptors by monitoring the dynamics of cyclic adenosine monophosphate (cAMP) level. The results showed that there were significant differences between adenosine receptors on real-time responses under stimulation. Moreover, the dynamics of cAMP level demonstrated that competition between adenosine receptors existed. Taken together, our study indicates that monitoring the dynamics of cAMP level using bioluminescence resonance energy transfer technique could be one potential approach to investigate the mechanism of competitions between adenosine receptors.

  8. Cyclic adenosine monophosphate phosphodiesterase in brain: effect on anxiety.

    PubMed

    Beer, B; Chasin, M; Clody, D E; Vogel, J R

    1972-04-28

    Drugs that reduce anxiety may be mediated by cyclic adenosine monophosphate in the brain because (i) potent anxiety-reducing drugs are also potent inhibitors of brain phosphodiesterase activity; (ii) dibutyryl cyclic adenosine monophosphate has the ability to reduce anxiety; (iii) the methylxanthines show significant anxiety-reducing effects; (iv) theophylline and chlordiazepoxide produce additive anxiety-reducing activity; and (v) there is a significant correlation between the anxiety-reducing property of drugs and their ability to inhibit phosphodiesterase activity in the brain. PMID:4402069

  9. Why do premature newborn infants display elevated blood adenosine levels?

    PubMed

    Panfoli, Isabella; Cassanello, Michela; Bruschettini, Matteo; Colella, Marina; Cerone, Roberto; Ravera, Silvia; Calzia, Daniela; Candiano, Giovanni; Ramenghi, Luca

    2016-05-01

    Our preliminary data show high levels of adenosine in the blood of very low birth weight (VLBW) infants, positively correlating to their prematurity (i.e. body weight class). This prompted us to look for a mechanism promoting such impressive adenosine increase. We hypothesized a correlation with oxygen challenge. In fact, it is recognized that either oxygen lack or its excess contribute to the pathogenesis of the injuries of prematurity, such as retinopathy (ROP) and periventricular white matter lesions (PWMI). The optimal concentration of oxygen for resuscitation of VLBW infants is currently under revision. We propose that the elevated adenosine blood concentrations of VLBW infants recognizes two sources. The first could be its activity-dependent release from unmyelinated brain axons. Adenosine in this respect would be an end-product of the hypometabolic VLBW newborn unmyelinated axon intensely firing in response to the environmental stimuli consequent to premature birth. Adenosine would be eventually found in the blood due to blood-brain barrier immaturity. In fact, adenosine is the primary activity-dependent signal promoting differentiation of premyelinating oligodendrocyte progenitor cells (OPC) into myelinating cells in the Central Nervous System, while inhibiting their proliferation and inhibiting synaptic function. The second, would be the ecto-cellular ATP synthesized by the endothelial cell plasmalemma exposed to ambient oxygen concentrations due to premature breathing, especially in lung. ATP would be rapidly transformed into adenosine by the ectonucleotidase activities such as NTPDase I (CD39), and NT5E (CD73). An ectopic extra-mitochondrial aerobic ATP synthetic ability was reported in many cell plasma-membranes, among which endothelial cells. The potential implications of the cited hypotheses for the neonatology area would be great. The amount of oxygen administration for reviving of newborns would find a molecular basis for its assessment. VLBW

  10. Essential role of adenosine, adenosine A1 receptors, and ATP-sensitive K+ channels in cerebral ischemic preconditioning.

    PubMed Central

    Heurteaux, C; Lauritzen, I; Widmann, C; Lazdunski, M

    1995-01-01

    Preconditioning with sublethal ischemia protects against neuronal damage after subsequent lethal ischemic insults in hippocampal neurons. A pharmacological approach using agonists and antagonists at the adenosine A1 receptor as well as openers and blockers of ATP-sensitive K+ channels has been combined with an analysis of neuronal death and gene expression of subunits of glutamate and gamma-aminobutyric acid receptors, HSP70, c-fos, c-jun, and growth factors. It indicates that the mechanism of ischemic tolerance involves a cascade of events including liberation of adenosine, stimulation of adenosine A1 receptors, and, via these receptors, opening of sulfonylurea-sensitive ATP-sensitive K+ channels. Images Fig. 2 Fig. 3 PMID:7753861

  11. Phosphorylation of adenosine in renal brush-border membrane vesicles by an exchange reaction catalysed by adenosine kinase.

    PubMed Central

    Sayós, J; Solsona, C; Mallol, J; Lluis, C; Franco, R

    1994-01-01

    Uptake of [3H]adenosine in brush-border membrane (BBM) vesicles from either rat or pig kidney leads to an accumulation of intravesicular [3H]AMP. The lack of significant levels of ATP and the presence of AMP in BBM indicated that a phosphotransfer between [3H]adenosine and AMP occurs. The phosphotransfer activity is inhibited by iodotubercidin, which suggests that it is performed by adenosine kinase acting in an ATP-independent manner. The existence of a similar phosphotransferase activity was demonstrated in membrane-free extracts from pig kidney. From the compounds tested it was shown that a variety of mononucleotides could act as phosphate donors. The results suggest that phosphotransfer reactions may be physiologically relevant in kidney. PMID:8110185

  12. ATP-Sensitive K+ Channels Regulate the Concentrative Adenosine Transporter CNT2 following Activation by A1 Adenosine Receptors

    PubMed Central

    Duflot, Sylvie; Riera, Bárbara; Fernández-Veledo, Sonia; Casadó, Vicent; Norman, Robert I.; Casado, F. Javier; Lluís, Carme; Franco, Rafael; Pastor-Anglada, Marçal

    2004-01-01

    This study describes a novel mechanism of regulation of the high-affinity Na+-dependent adenosine transporter (CNT2) via the activation of A1 adenosine receptors (A1R). This regulation is mediated by the activation of ATP-sensitive K+ (KATP) channels. The high-affinity Na+-dependent adenosine transporter CNT2 and A1R are coexpressed in the basolateral domain of the rat hepatocyte plasma membrane and are colocalized in the rat hepatoma cell line FAO. The transient increase in CNT2-mediated transport activity triggered by (−)-N6-(2-phenylisopropyl)adenosine is fully inhibited by KATP channel blockers and mimicked by a KATP channel opener. A1R agonist activation of CNT2 occurs in both hepatocytes and FAO cells, which express Kir6.1, Kir6.2, SUR1, SUR2A, and SUR2B mRNA channel subunits. With the available antibodies against Kir6.X, SUR2A, and SUR2B, it is shown that all of these proteins colocalize with CNT2 and A1R in defined plasma membrane domains of FAO cells. The extent of the purinergic modulation of CNT2 is affected by the glucose concentration, a finding which indicates that glycemia and glucose metabolism may affect this cross-regulation among A1R, CNT2, and KATP channels. These results also suggest that the activation of KATP channels under metabolic stress can be mediated by the activation of A1R. Cell protection under these circumstances may be achieved by potentiation of the uptake of adenosine and its further metabolization to ATP. Mediation of purinergic responses and a connection between the intracellular energy status and the need for an exogenous adenosine supply are novel roles for KATP channels. PMID:15024061

  13. The adenosine metabolite inosine is a functional agonist of the adenosine A2A receptor with a unique signaling bias.

    PubMed

    Welihinda, Ajith A; Kaur, Manmeet; Greene, Kelly; Zhai, Yongjiao; Amento, Edward P

    2016-06-01

    Inosine is an endogenous purine nucleoside that is produced by catabolism of adenosine. Adenosine has a short half-life (approximately 10s) and is rapidly deaminated to inosine, a stable metabolite with a half-life of approximately 15h. Resembling adenosine, inosine acting through adenosine receptors (ARs) exerts a wide range of anti-inflammatory and immunomodulatory effects in vivo. The immunomodulatory effects of inosine in vivo, at least in part, are mediated via the adenosine A2A receptor (A2AR), an observation that cannot be explained fully by in vitro pharmacological characterization of inosine at the A2AR. It is unclear whether the in vivo effects of inosine are due to inosine or a metabolite of inosine engaging the A2AR. Here, utilizing a combination of label-free, cell-based, and membrane-based functional assays in conjunction with an equilibrium agonist-binding assay we provide evidence for inosine engagement at the A2AR and subsequent activation of downstream signaling events. Inosine-mediated A2AR activation leads to cAMP production with an EC50 of 300.7μM and to extracellular signal-regulated kinase-1 and -2 (ERK1/2) phosphorylation with an EC50 of 89.38μM. Our data demonstrate that inosine produces ERK1/2-biased signaling whereas adenosine produces cAMP-biased signaling at the A2AR, highlighting pharmacological differences between these two agonists. Given the in vivo stability of inosine, our data suggest an additional, previously unrecognized, mechanism that utilizes inosine to functionally amplify and prolong A2AR activation in vivo. PMID:26903141

  14. Adenosine-dependent activation of tyrosine hydroxylase is defective in adenosine kinase-deficient PC12 cells.

    PubMed Central

    Erny, R; Wagner, J A

    1984-01-01

    (R)-N6-Phenylisopropyladenosine (PIA) stimulates dopa production 3- to 5-fold in PC12 cells, with a half-maximal effective concentration (EC50) of 50 nM. This increase can be explained by a stable activation of tyrosine hydroxylase [TyrOHase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] when it is phosphorylated by a cAMP-dependent protein kinase. The activation of TyrOHase is mediated by the adenosine-dependent activation of adenylate cyclase (EC50 = 600 nM). PIA (10 microM) is as effective as cholera toxin or dibutyryl cAMP in activating TyrOHase in wild-type cells. Adenosine kinase-deficient mutants of PC12 were found to be resistant to PIA-dependent activation of TyrOHase (EC50 = 100-1000 nM). This phenomenon was explored in detail in one adenosine kinase-deficient mutant and was shown to occur because the mutant was resistant to the adenosine-dependent activation of adenylate cyclase. In this mutant, TyrOHase was activated 14-fold by cholera toxin, suggesting that activated TyrOHase is about 14 times as active as unactivated TyrOHase. These studies with kinase-deficient PC12 cells provide genetic evidence that adenosine-dependent activation of TyrOHase is mediated by acute increases in cAMP. When the adenosine receptor found on PC12 cells is expressed in vivo, it might function as either a presynaptic (i.e., localized on the nerve terminal) or a postsynaptic (i.e., localized on the cell body or dendrite) receptor that regulates rates of transmitter synthesis in response to cell activity. PMID:6146982

  15. Adenosine transporters and receptors: key elements for retinal function and neuroprotection.

    PubMed

    Dos Santos-Rodrigues, Alexandre; Pereira, Mariana R; Brito, Rafael; de Oliveira, Nádia A; Paes-de-Carvalho, Roberto

    2015-01-01

    Adenosine is an important neuroactive substance in the central nervous system, including in the retina where subclasses of adenosine receptors and transporters are expressed since early stages of development. Here, we review some evidence showing that adenosine plays important functions in the mature as well as in the developing tissue. Adenosine transporters are divided into equilibrative and concentrative, and the major transporter subtype present in the retina is the ENT1. This transporter is responsible for a bidirectional transport of adenosine and the uptake or release of this nucleoside appears to be regulated by different signaling pathways that are also controlled by activation of adenosine receptors. Adenosine receptors are also key players in retina physiology regulating a variety of functions in the mature and developing tissue. Regulation of excitatory neurotransmitter release and neuroprotection are the main functions played be adenosine in the mature tissue, while regulation of cell survival and neurogenesis are some of the functions played by adenosine in developing retina. Since adenosine is neuroprotective against excitotoxic and metabolic dysfunctions observed in neurological and ocular diseases, the search for adenosine-related drugs regulating adenosine transporters and receptors can be important for advancement of therapeutic strategies against these diseases. PMID:25817878

  16. Anticancer effect of adenosine on gastric cancer via diverse signaling pathways

    PubMed Central

    Tsuchiya, Ayako; Nishizaki, Tomoyuki

    2015-01-01

    Extracellular adenosine induces apoptosis in a variety of cancer cells via intrinsic and extrinsic pathways. In the former pathway, adenosine uptake into cells triggers apoptosis, and in the latter pathway, adenosine receptors mediate apoptosis. Extracellular adenosine also induces apoptosis of gastric cancer cells. Extracellular adenosine is transported into cells through an adenosine transporter and converted to AMP by adenosine kinase. In turn, AMP activates AMP-activated protein kinase (AMPK). AMPK is the factor responsible for caspase-independent apoptosis of GT3-TKB gastric cancer cells. Extracellular adenosine, on the other hand, induces caspase-dependent apoptosis of MKN28 and MKN45 gastric cancer cells by two mechanisms. Firstly, AMP, converted from intracellularly transported adenosine, initiates apoptosis, regardless of AMPK. Secondly, the A3 adenosine receptor, linked to Gi/Gq proteins, mediates apoptosis by activating the Gq protein effector, phospholipase Cγ, to produce inositol 1,4,5-trisphosphate and diacylglycerol, which activate protein kinase C. Consequently, the mechanisms underlying adenosine-induced apoptosis vary, depending upon gastric cancer cell types. Understand the contribution of each downstream target molecule of adenosine to apoptosis induction may aid the establishment of tailor-made chemotherapy for gastric cancer. PMID:26494951

  17. Neuronal transporter and astrocytic ATP exocytosis underlie activity-dependent adenosine release in the hippocampus

    PubMed Central

    Wall, Mark J; Dale, Nicholas

    2013-01-01

    The neuromodulator adenosine plays an important role in many physiological and pathological processes within the mammalian CNS. However, the precise mechanisms of how the concentration of extracellular adenosine increases following neural activity remain contentious. Here we have used microelectrode biosensors to directly measure adenosine release induced by focal stimulation in stratum radiatum of area CA1 in mouse hippocampal slices. Adenosine release was both action potential and Ca2+ dependent and could be evoked with low stimulation frequencies and small numbers of stimuli. Adenosine release required the activation of ionotropic glutamate receptors and could be evoked by local application of glutamate receptor agonists. Approximately 40% of stimulated-adenosine release occurred by translocation of adenosine via equilibrative nucleoside transporters (ENTs). This component of release persisted in the presence of the gliotoxin fluoroacetate and thus results from the direct release of adenosine from neurons. A reduction of adenosine release in the presence of NTPDase blockers, in slices from CD73−/− and dn-SNARE mice, provides evidence that a component of adenosine release arises from the extracellular metabolism of ATP released from astrocytes. This component of release appeared to have slower kinetics than the direct ENT-mediated release of adenosine. These data suggest that activity-dependent adenosine release is surprisingly complex and, in the hippocampus, arises from at least two distinct mechanisms with different cellular sources. PMID:23713028

  18. Anticancer effect of adenosine on gastric cancer via diverse signaling pathways.

    PubMed

    Tsuchiya, Ayako; Nishizaki, Tomoyuki

    2015-10-21

    Extracellular adenosine induces apoptosis in a variety of cancer cells via intrinsic and extrinsic pathways. In the former pathway, adenosine uptake into cells triggers apoptosis, and in the latter pathway, adenosine receptors mediate apoptosis. Extracellular adenosine also induces apoptosis of gastric cancer cells. Extracellular adenosine is transported into cells through an adenosine transporter and converted to AMP by adenosine kinase. In turn, AMP activates AMP-activated protein kinase (AMPK). AMPK is the factor responsible for caspase-independent apoptosis of GT3-TKB gastric cancer cells. Extracellular adenosine, on the other hand, induces caspase-dependent apoptosis of MKN28 and MKN45 gastric cancer cells by two mechanisms. Firstly, AMP, converted from intracellularly transported adenosine, initiates apoptosis, regardless of AMPK. Secondly, the A3 adenosine receptor, linked to Gi/Gq proteins, mediates apoptosis by activating the Gq protein effector, phospholipase Cγ, to produce inositol 1,4,5-trisphosphate and diacylglycerol, which activate protein kinase C. Consequently, the mechanisms underlying adenosine-induced apoptosis vary, depending upon gastric cancer cell types. Understand the contribution of each downstream target molecule of adenosine to apoptosis induction may aid the establishment of tailor-made chemotherapy for gastric cancer. PMID:26494951

  19. Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix.

    PubMed

    Briggs, David C; Birchenough, Holly L; Ali, Tariq; Rugg, Marilyn S; Waltho, Jon P; Ievoli, Elena; Jowitt, Thomas A; Enghild, Jan J; Richter, Ralf P; Salustri, Antonietta; Milner, Caroline M; Day, Anthony J

    2015-11-27

    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix. PMID:26468290

  20. Metal Ion-dependent Heavy Chain Transfer Activity of TSG-6 Mediates Assembly of the Cumulus-Oocyte Matrix*

    PubMed Central

    Briggs, David C.; Birchenough, Holly L.; Ali, Tariq; Rugg, Marilyn S.; Waltho, Jon P.; Ievoli, Elena; Jowitt, Thomas A.; Enghild, Jan J.; Richter, Ralf P.; Salustri, Antonietta; Milner, Caroline M.; Day, Anthony J.

    2015-01-01

    The matrix polysaccharide hyaluronan (HA) has a critical role in the expansion of the cumulus cell-oocyte complex (COC), a process that is necessary for ovulation and fertilization in most mammals. Hyaluronan is organized into a cross-linked network by the cooperative action of three proteins, inter-α-inhibitor (IαI), pentraxin-3, and TNF-stimulated gene-6 (TSG-6), driving the expansion of the COC and providing the cumulus matrix with its required viscoelastic properties. Although it is known that matrix stabilization involves the TSG-6-mediated transfer of IαI heavy chains (HCs) onto hyaluronan (to form covalent HC·HA complexes that are cross-linked by pentraxin-3) and that this occurs via the formation of covalent HC·TSG-6 intermediates, the underlying molecular mechanisms are not well understood. Here, we have determined the tertiary structure of the CUB module from human TSG-6, identifying a calcium ion-binding site and chelating glutamic acid residue that mediate the formation of HC·TSG-6. This occurs via an initial metal ion-dependent, non-covalent, interaction between TSG-6 and HCs that also requires the presence of an HC-associated magnesium ion. In addition, we have found that the well characterized hyaluronan-binding site in the TSG-6 Link module is not used for recognition during transfer of HCs onto HA. Analysis of TSG-6 mutants (with impaired transferase and/or hyaluronan-binding functions) revealed that although the TSG-6-mediated formation of HC·HA complexes is essential for the expansion of mouse COCs in vitro, the hyaluronan-binding function of TSG-6 does not play a major role in the stabilization of the murine cumulus matrix. PMID:26468290

  1. Amelioration of adriamycin and daunorubicin myocardial toxicity by adenosine.

    PubMed

    Newman, R A; Hacker, M P; Krakoff, I H

    1981-09-01

    Primary cultures of rat myocardial cells were used to investigate the dose and time-dependent cellular enzyme release induced by either Adriamycin or daunorubicin, Concentrations of either anthracycline (1.8 or 18 microM) produced significant release of creatine phosphokinase and lactic dehydrogenase from myocardial cells within 24 hr of exposure without a detectable decrease in cell viability. Preincubation of the myocardial cells with varying concentrations of adenosine (10 microM to 1 mM) for 24 hr prior to the addition of anthracycline decreased or prevented drug-induced enzyme release. Other putative myocardial protectants, i.e., N-acetyl-L-cysteine, alpha-tocopherol, or carnitine, were ineffective in preventing anthracycline-induced enzyme release. Although adenosine was an effective myocardial protectant, it had no significant effect on cellular uptake of daunorubicin, nor did adenosine adversely affect the oncolytic activity of daunorubicin against L1210 leukemia cells in vitro. Anthramycin, another oncolytic agent having reported cardiotoxic effects, was also tested in the in vitro system. With this drug, however, no enzyme release was detected at less than lethal doses nor did adenosine have any protective potential against the toxicity of anthramycin. Finally, Adriamycin caused no significant lactic dehydrogenase release when incubated at 1.8 or 18 microM with H9c2 cells, a cell line having primarily skeletal muscle characteristics. This result suggests a specific toxicity of anthracyclines for myocardial but not skeletal muscle cells. PMID:7260911

  2. CD39/Adenosine Pathway Is Involved in AIDS Progression

    PubMed Central

    Limou, Sophie; Younas, Mehwish; Kök, Ayrin; Huë, Sophie; Seddiki, Nabila; Hulin, Anne; Delaneau, Olivier; Schuitemaker, Hanneke; Herbeck, Joshua T.; Mullins, James I.; Muhtarova, Maria; Bensussan, Armand; Zagury, Jean-François; Lelievre, Jean-Daniel; Lévy, Yves

    2011-01-01

    HIV-1 infection is characterized by a chronic activation of the immune system and suppressed function of T lymphocytes. Regulatory CD4+ CD25high FoxP3+CD127low T cells (Treg) play a key role in both conditions. Here, we show that HIV-1 positive patients have a significant increase of Treg-associated expression of CD39/ENTPD1, an ectoenzyme which in concert with CD73 generates adenosine. We show in vitro that the CD39/adenosine axis is involved in Treg suppression in HIV infection. Treg inhibitory effects are relieved by CD39 down modulation and are reproduced by an adenosine-agonist in accordance with a higher expression of the adenosine A2A receptor on patients' T cells. Notably, the expansion of the Treg CD39+ correlates with the level of immune activation and lower CD4+ counts in HIV-1 infected patients. Finally, in a genetic association study performed in three different cohorts, we identified a CD39 gene polymorphism that was associated with down-modulated CD39 expression and a slower progression to AIDS. PMID:21750674

  3. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  4. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  5. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  6. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  7. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  8. Striatal adenosine-cannabinoid receptor interactions in rats over-expressing adenosine A2A receptors.

    PubMed

    Chiodi, Valentina; Ferrante, Antonella; Ferraro, Luca; Potenza, Rosa Luisa; Armida, Monica; Beggiato, Sarah; Pèzzola, Antonella; Bader, Michael; Fuxe, Kjell; Popoli, Patrizia; Domenici, Maria Rosaria

    2016-03-01

    Adenosine A2A receptors (A2 A Rs) and cannabinoid CB1 receptors (CB1 Rs) are highly expressed in the striatum, where they functionally interact and form A2A /CB1 heteroreceptor complexes. We investigated the effects of CB1 R stimulation in a transgenic rat strain over-expressing A2 A Rs under the control of the neural-specific enolase promoter (NSEA2A rats) and in age-matched wild-type (WT) animals. The effects of the CB1 R agonist WIN 55,212-2 (WIN) were significantly lower in NSEA2A rats than in WT animals, as demonstrated by i) electrophysiological recordings of synaptic transmission in corticostriatal slices; ii) the measurement of glutamate outflow from striatal synaptosomes and iii) in vivo experiments on locomotor activity. Moreover, while the effects of WIN were modulated by both A2 A R agonist (CGS 21680) and antagonists (ZM 241385, KW-6002 and SCH-442416) in WT animals, the A2 A R antagonists failed to influence WIN-mediated effects in NSEA2A rats. The present results demonstrate that in rats with genetic neuronal over-expression of A2 A Rs, the effects mediated by CB1 R activation in the striatum are significantly reduced, suggesting a change in the stoichiometry of A2A and CB1 receptors and providing a strategy to dissect the involvement of A2 A R forming or not forming heteromers in the modulation of striatal functions. These findings add additional evidence for the existence of an interaction between striatal A2 A Rs and CB1 Rs, playing a fundamental role in the regulation of striatal functions. We studied A2A -CB1 receptor interaction in transgenic rats over-expressing adenosine A2A receptors under the control of the neuron-specific enolase promoter (NSEA2A ). In these rats, we demonstrated a reduced effect of the CB1 receptor agonist WIN 55,212-2 in the modulation of corticostriatal synaptic transmission and locomotor activity, while CB1 receptor expression level did not change with respect to WT rats. A reduction in the expression of A2A -CB1

  9. Adenosine induces G2/M cell-cycle arrest by inhibiting cell mitosis progression.

    PubMed

    Jia, Kun-Zhi; Tang, Bo; Yu, Lu; Cheng, Wei; Zhang, Rong; Zhang, Jian-Fa; Hua, Zi-Chun

    2010-01-01

    Cellular adenosine accumulates under stress conditions. Few papers on adenosine are concerned with its function in the cell cycle. The cell cycle is the essential mechanism by which all living things reproduce and the target machinery when cells encounter stresses, so it is necessary to examine the relationship between adenosine and the cell cycle. In the present study, adenosine was found to induce G-2/M cell-cycle arrest. Furthermore, adenosine was found to modulate the expression of some important proteins in the cell cycle, such as cyclin B and p21, and to inhibit the transition of metaphase to anaphase in mitosis. PMID:19947935

  10. The adenosine system modulates Toll-like receptor function: basic mechanisms, clinical correlates and translational opportunities

    PubMed Central

    Coombs, Melanie R. Power; Belderbos, Mirjam E.; Gallington, Leighanne C.; Bont, Louis; Levy, Ofer

    2014-01-01

    Adenosine is an endogenous purine metabolite whose concentration in human blood plasma rises from nanomolar to micromolar during stress or hypoxia. Leukocytes express seven-transmembrane adenosine receptors whose engagement modulates Toll-like receptor-mediated cytokine responses, in part via modulation of intracellular cyclic adenosine monophosphate (cAMP). Adenosine congeners are used clinically to treat arrhythmias and apnea of prematurity. Herein we consider the potential of adenosine congeners as innate immune response modifiers to prevent and/or treat infection. PMID:21342073

  11. Manipulation of adenosine kinase affects sleep regulation in mice

    PubMed Central

    Palchykova, Svitlana; Winsky-Sommerer, Raphaelle; Shen, Hai-Ying; Boison, Detlev; Gerling, Andrea; Tobler, Irene

    2010-01-01

    Sleep and sleep intensity are enhanced by adenosine and its receptor agonists, while adenosine receptor antagonists induce wakefulness. Adenosine kinase (ADK) is the primary enzyme metabolizing adenosine in adult brain. To investigate whether adenosine metabolism or clearance affects sleep we recorded sleep in mice with engineered mutations in Adk. Adk-tg mice over-express a transgene encoding the cytoplasmic isoform of ADK in the brain, but lack the nuclear isoform of the enzyme. Wild-type mice and Adk+/− mice that have a 50% reduction of the cytoplasmic and the nuclear isoforms of ADK served as controls. Adk-tg mice showed a remarkable reduction of EEG power in low frequencies in all vigilance states and in theta activity (6.25–11 Hz) in REM sleep and waking. Adk-tg mice were awake 58 min more per day than wild-type mice and spent significantly less time in REM sleep (102±3 vs 128±3 min in wild-type). After sleep deprivation slow-wave activity (0.75–4 Hz), the intensity component of NREM sleep, increased significantly less in Adk-tg mice and their slow-wave energy was reduced. In contrast, the vigilance states and EEG spectra of Adk+/− and wild-type mice did not differ. Our data suggest that over-expression of the cytoplasmic isoform of ADK is sufficient to alter sleep physiology. ADK might orchestrate neurotransmitter pathways involved in the generation of EEG oscillations and regulation of sleep. PMID:20881134

  12. Feed-Forward Inhibition of CD73 and Upregulation of Adenosine Deaminase Contribute to the Loss of Adenosine Neuromodulation in Postinflammatory Ileitis

    PubMed Central

    Magalhães-Cardoso, Maria Teresa; Ferreirinha, Fátima; Dias, Ana Sofia; Pelletier, Julie

    2014-01-01

    Purinergic signalling is remarkably plastic during gastrointestinal inflammation. Thus, selective drugs targeting the “purinome” may be helpful for inflammatory gastrointestinal diseases. The myenteric neuromuscular transmission of healthy individuals is fine-tuned and controlled by adenosine acting on A2A excitatory receptors. Here, we investigated the neuromodulatory role of adenosine in TNBS-inflamed longitudinal muscle-myenteric plexus of the rat ileum. Seven-day postinflammation ileitis lacks adenosine neuromodulation, which may contribute to acceleration of gastrointestinal transit. The loss of adenosine neuromodulation results from deficient accumulation of the nucleoside at the myenteric synapse despite the fact that the increases in ATP release were observed. Disparity between ATP outflow and adenosine deficit in postinflammatory ileitis is ascribed to feed-forward inhibition of ecto-5′-nucleotidase/CD73 by high extracellular ATP and/or ADP. Redistribution of NTPDase2, but not of NTPDase3, from ganglion cell bodies to myenteric nerve terminals leads to preferential ADP accumulation from released ATP, thus contributing to the prolonged inhibition of muscle-bound ecto-5′-nucleotidase/CD73 and to the delay of adenosine formation at the inflamed neuromuscular synapse. On the other hand, depression of endogenous adenosine accumulation may also occur due to enhancement of adenosine deaminase activity. Both membrane-bound and soluble forms of ecto-5′-nucleotidase/CD73 and adenosine deaminase were detected in the inflamed myenteric plexus. These findings provide novel therapeutic targets for inflammatory gut motility disorders. PMID:25210228

  13. Modulation of bladder function by luminal adenosine turnover and A1 receptor activation

    PubMed Central

    Prakasam, H. Sandeep; Herrington, Heather; Roppolo, James R.; Jackson, Edwin K.

    2012-01-01

    The bladder uroepithelium transmits information to the underlying nervous and musculature systems, is under constant cyclical strain, expresses all four adenosine receptors (A1, A2A, A2B, and A3), and is a site of adenosine production. Although adenosine has a well-described protective effect in several organs, there is a lack of information about adenosine turnover in the uroepithelium or whether altering luminal adenosine concentrations impacts bladder function or overactivity. We observed that the concentration of extracellular adenosine at the mucosal surface of the uroepithelium was regulated by ecto-adenosine deaminase and by equilibrative nucleoside transporters, whereas adenosine kinase and equilibrative nucleoside transporters modulated serosal levels. We further observed that enriching endogenous adenosine by blocking its routes of metabolism or direct activation of mucosal A1 receptors with 2-chloro-N6-cyclopentyladenosine (CCPA), a selective agonist, stimulated bladder activity by lowering the threshold pressure for voiding. Finally, CCPA did not quell bladder hyperactivity in animals with acute cyclophosphamide-induced cystitis but instead exacerbated their irritated bladder phenotype. In conclusion, we find that adenosine levels at both surfaces of the uroepithelium are modulated by turnover, that blocking these pathways or stimulating A1 receptors directly at the luminal surface promotes bladder contractions, and that adenosine further stimulates voiding in animals with cyclophosphamide-induced cystitis. PMID:22552934

  14. Metabolic changes of cultured DRG neurons induced by adenosine using confocal microscopy imaging

    NASA Astrophysics Data System (ADS)

    Zheng, Liqin; Huang, Yimei; Chen, Jiangxu; Wang, Yuhua; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

    2012-12-01

    Adenosine exerts multiple effects on pain transmission in the peripheral nervous system. This study was performed to use confocal microscopy to evaluate whether adenosine could affect dorsal root ganglia (DRG) neurons in vitro and test which adenosine receptor mediates the effect of adenosine on DRG neurons. After adding adenosine with different concentration, we compared the metabolic changes by the real time imaging of calcium and mitochondria membrane potential using confocal microscopy. The results showed that the effect of 500 μM adenosine on the metabolic changes of DRG neurons was more significant than others. Furthermore, four different adenosine receptor antagonists were used to study which receptor mediated the influences of adenosine on the cultured DRG neurons. All adenosine receptor antagonists especially A1 receptor antagonist (DPCPX) had effect on the Ca2+ and mitochondria membrane potential dynamics of DRG neurons. The above studies demonstrated that the effect of adenosine which may be involved in the signal transmission on the sensory neurons was dose-dependent, and all the four adenosine receptors especially the A1R may mediate the transmission.

  15. Neuronal adenosine release, and not astrocytic ATP release, mediates feedback inhibition of excitatory activity

    PubMed Central

    Lovatt, Ditte; Xu, Qiwu; Liu, Wei; Takano, Takahiro; Smith, Nathan A.; Schnermann, Jurgen; Tieu, Kim; Nedergaard, Maiken

    2012-01-01

    Adenosine is a potent anticonvulsant acting on excitatory synapses through A1 receptors. Cellular release of ATP, and its subsequent extracellular enzymatic degradation to adenosine, could provide a powerful mechanism for astrocytes to control the activity of neural networks during high-intensity activity. Despite adenosine's importance, the cellular source of adenosine remains unclear. We report here that multiple enzymes degrade extracellular ATP in brain tissue, whereas only Nt5e degrades AMP to adenosine. However, endogenous A1 receptor activation during cortical seizures in vivo or heterosynaptic depression in situ is independent of Nt5e activity, and activation of astrocytic ATP release via Ca2+ photolysis does not trigger synaptic depression. In contrast, selective activation of postsynaptic CA1 neurons leads to release of adenosine and synaptic depression. This study shows that adenosine-mediated synaptic depression is not a consequence of astrocytic ATP release, but is instead an autonomic feedback mechanism that suppresses excitatory transmission during prolonged activity. PMID:22421436

  16. Proximity Binding and Metal Ion-Dependent DNAzyme Cyclic Amplification-Integrated Aptasensor for Label-Free and Sensitive Electrochemical Detection of Thrombin.

    PubMed

    Yang, Jianmei; Dou, Baoting; Yuan, Ruo; Xiang, Yun

    2016-08-16

    Thrombin plays important roles for the diagnosis of neurodegenerative and cardiovascular diseases. By integrating proximity binding-induced strand displacement and metal ion-dependent DNAzyme recycling amplification, we demonstrate here the development of a simple and sensitive strategy for the detection of thrombin in human serums. The binding of the two distinct aptamers to the thrombin targets increases the local concentration of the aptamers and facilitates the release of the enzymatic sequences through proximity binding-induced strand displacement. The liberated enzymatic sequences further hybridize with the G-quadruplex containing and hairpin-structured substrate sequences on the sensor electrode to form the metal-ion dependent DNAzymes. Subsequently, the metal ions catalyze the cleavage of the substrate sequences to unlock the G-quadruplex forming sequences and to release the enzymatic sequences to trigger another cleavage cycle. Such metal ion-dependent DNAzyme recycling amplification leads to the formation of many active G-quadruplex forming sequences, which associate with hemin to form G-quadruplex/hemin complexes on the electrode surface. Direct electron transfer of hemin to the electrode during the potential scan can thus generate significantly amplified current for sensitive detection of thrombin at the low picomolar level. The work demonstrated here can thus offer new opportunities for the development of convenient signal amplification strategies for detecting various protein targets. PMID:27436431

  17. Adenosine protected against pulmonary edema through transporter- and receptor A2-mediated endothelial barrier enhancement

    PubMed Central

    Lu, Qing; Harrington, Elizabeth O.; Newton, Julie; Casserly, Brian; Radin, Gregory; Warburton, Rod; Zhou, Yang; Blackburn, Michael R.

    2010-01-01

    We have previously demonstrated that adenosine plus homocysteine enhanced endothelial basal barrier function and protected against agonist-induced barrier dysfunction in vitro through attenuation of RhoA activation by inhibition of isoprenylcysteine-O-carboxyl methyltransferase. In the current study, we tested the effect of elevated adenosine on pulmonary endothelial barrier function in vitro and in vivo. We noted that adenosine alone dose dependently enhanced endothelial barrier function. While adenosine receptor A1 or A3 antagonists were ineffective, an adenosine transporter inhibitor, NBTI, or a combination of DPMX and MRS1754, antagonists for adenosine receptors A2A and A2B, respectively, partially attenuated the barrier-enhancing effect of adenosine. Similarly, inhibition of both A2A and A2B receptors with siRNA also blunted the effect of adenosine on barrier function. Interestingly, inhibition of both transporters and A2A/A2B receptors completely abolished adenosine-induced endothelial barrier enhancement. The adenosine receptor A2A and A2B agonist, NECA, also significantly enhanced endothelial barrier function. These data suggest that both adenosine transporters and A2A and A2B receptors are necessary for exerting maximal effect of adenosine on barrier enhancement. We also found that adenosine enhanced Rac1 GTPase activity and overexpression of dominant negative Rac1 attenuated adenosine-induced increases in focal adhesion complexes. We further demonstrated that elevation of cellular adenosine by inhibition of adenosine deaminase with Pentostatin significantly enhanced endothelial basal barrier function, an effect that was also associated with enhanced Rac1 GTPase activity and with increased focal adhesion complexes and adherens junctions. Finally, using a non-inflammatory acute lung injury (ALI) model induced by α-naphthylthiourea, we found that administration of Pentostatin, which elevated lung adenosine level by 10-fold, not only attenuated the

  18. Sustained adenosine exposure causes lung endothelial apoptosis: a possible contributor to cigarette smoke-induced endothelial apoptosis and lung injury

    PubMed Central

    Sakhatskyy, Pavlo; Newton, Julie; Shamirian, Paul; Hsiao, Vivian; Curren, Sean; Gabino Miranda, Gustavo Andres; Pedroza, Mesias; Blackburn, Michael R.; Rounds, Sharon

    2013-01-01

    Pulmonary endothelial cell (EC) apoptosis has been implicated in the pathogenesis of emphysema. Cigarette smoke (CS) causes lung EC apoptosis and emphysema. In this study, we show that CS exposure increased lung tissue adenosine levels in mice, an effect associated with increased lung EC apoptosis and the development of emphysema. Adenosine has a protective effect against apoptosis via adenosine receptor-mediated signaling. However, sustained elevated adenosine increases alveolar cell apoptosis in adenosine deaminase-deficient mice. We established an in vitro model of sustained adenosine exposure by incubating lung EC with adenosine in the presence of an adenosine deaminase inhibitor, deoxycoformicin. We demonstrated that sustained adenosine exposure caused lung EC apoptosis via nucleoside transporter-facilitated intracellular adenosine uptake, subsequent activation of p38 and JNK in mitochondria, and ultimately mitochondrial defects and activation of the mitochondria-mediated intrinsic pathway of apoptosis. Our results suggest that sustained elevated adenosine may contribute to CS-induced lung EC apoptosis and emphysema. Our data also reconcile the paradoxical effects of adenosine on apoptosis, demonstrating that prolonged exposure causes apoptosis via nucleoside transporter-mediated intracellular adenosine signaling, whereas acute exposure protects against apoptosis via activation of adenosine receptors. Inhibition of adenosine uptake may become a new therapeutic target in treatment of CS-induced lung diseases. PMID:23316066

  19. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice.

    PubMed

    Witts, Emily C; Nascimento, Filipe; Miles, Gareth B

    2015-10-01

    Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925-1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output. PMID:26311185

  20. Abiotic regioselective phosphorylation of adenosine with borate in formamide.

    PubMed

    Furukawa, Yoshihiro; Kim, Hyo-Joong; Hutter, Daniel; Benner, Steven A

    2015-04-01

    Nearly 40 years ago, Schoffstall and his coworkers used formamide as a solvent to permit the phosphorylation of nucleosides by inorganic phosphate to give nucleoside phosphates, which (due to their thermodynamic instability with respect to hydrolysis) cannot be easily created in water by an analogous phosphorylation (the "water problem" in prebiotic chemistry). More recently, we showed that borate could stabilize certain carbohydrates against degradation (the "asphalt problem"). Here, we combine the two concepts to show that borate can work in formamide to guide the reactivity of nucleosides under conditions where they are phosphorylated. Specifically, reaction of adenosine in formamide with inorganic phosphate and pyrophosphate in the presence of borate gives adenosine-5'-phosphate as the only detectable phosphorylated product, with formylation (as opposed to hydrolysis) being the competing reaction. PMID:25826074

  1. Adenosine: an endogenous mediator in the pathogenesis of psoriasis*

    PubMed Central

    Festugato, Moira

    2015-01-01

    It is known that inflammatory and immune responses protect us from the invasion of micro-organisms and eliminate "wastes" from the injured sites, but they may also be responsible for significant tissue damage. Adenosine, as a purine nucleoside, which is produced in inflamed or injured sites, fulfills its role in limiting tissue damage. Although, it may have a pleiotropic effect, which signals it with a proinflammatory state in certain situations, it can be considered a potent anti-inflammatory mediator. The effects of adenosine, which acts through its receptors on T cell, on mast cell and macrophages, on endothelial cells, on neutrophils and dendritic cells, as they indicate TNF-alpha and cytokines, show that this mediator has a central role in the pathogenesis of psoriasis. The way it acts in psoriasis will be reviewed in this study. PMID:26734868

  2. Extracellular adenosine levels are associated with the progression and exacerbation of pulmonary fibrosis.

    PubMed

    Luo, Fayong; Le, Ngoc-Bao; Mills, Tingting; Chen, Ning-Yuan; Karmouty-Quintana, Harry; Molina, Jose G; Davies, Jonathan; Philip, Kemly; Volcik, Kelly A; Liu, Hong; Xia, Yang; Eltzschig, Holger K; Blackburn, Michael R

    2016-02-01

    Idiopathic pulmonary fibrosis is a devastating lung disease with limited treatment options. The signaling molecule adenosine is produced in response to injury and serves a protective role in early stages of injury and is detrimental during chronic stages of disease such as seen in lung conditions such as pulmonary fibrosis. Understanding the association of extracellular adenosine levels and the progression of pulmonary fibrosis is critical for designing adenosine based approaches to treat pulmonary fibrosis. The goal of this study was to use various models of experimental lung fibrosis to understand when adenosine levels are elevated during pulmonary fibrosis and whether these elevations were associated with disease progression and severity. To accomplish this, extracellular adenosine levels, defined as adenosine levels found in bronchioalveolar lavage fluid, were determined in mouse models of resolvable and progressive pulmonary fibrosis. We found that relative bronchioalveolar lavage fluid adenosine levels are progressively elevated in association with pulmonary fibrosis and that adenosine levels diminish in association with the resolution of lung fibrosis. In addition, treatment of these models with dipyridamole, an inhibitor of nucleoside transporters that potentiates extracellular adenosine levels, demonstrated that the resolution of lung fibrosis is blocked by the failure of adenosine levels to subside. Furthermore, exacerbating adenosine levels led to worse fibrosis in a progressive fibrosis model. Increased adenosine levels were associated with elevation of IL-6 and IL-17, which are important inflammatory cytokines in pulmonary fibrosis. These results demonstrate that extracellular adenosine levels are closely associated with the progression of experimental pulmonary fibrosis and that this signaling pathway may mediate fibrosis by regulating IL-6 and IL-17 production. PMID:26527068

  3. Pharmacology of the Adenosine A3 Receptor in the Vasculature and Essential Hypertension

    PubMed Central

    Ho, Ming-Fen; Low, Leanne M.; Rose’Meyer, Roselyn B.

    2016-01-01

    Background Essential hypertension is considered to be a multifactorial disorder and its aetiology has yet to be clearly identified. As the adenosine receptors have a significant role in mediating vasodilation, alterations in their structures or signalling pathways may be involved in the development of hypertension. This study aimed to measure the expression of adenosine A3 receptors in a range of cardiovascular tissues and determine whether they could be altered with essential hypertension, and to functionally test responses to adenosine A3 receptor agonists in coronary blood vessels using the isolated perfused heart preparation. Methods mRNA samples from cardiovascular tissues and a range of blood vessels were collected from 10 week old male spontaneously hypertensive rats and age-gender matched Wistar rats (n = 8). The Langendorff heart perfusion preparation was used to characterise adenosine A3 receptor mediated coronary vasodilation in the rat heart. Results Adenosine A3 receptor agonists induced coronary vasodilation. The expression of adenosine A3 receptors in cardiovascular tissues was altered in a tissue-specific pattern. Specifically, down-regulation of adenosine A3 receptor expression occurred in hypertensive hearts, which might be associated with attenuated vasodilator responses observed in coronary vessels to adenosine A3 receptor agonists. Conclusions This study demonstrated alterations in the expression of adenosine A3 receptors occurred in a tissue specific mode, and reduced adenosine A3 receptor mediated coronary vasodilation in hearts from spontaneously hypertensive rats. Our findings with regard to changes in the adenosine A3 receptor in hypertensive hearts suggest that adenosine A3 receptor might play a role in the physiopathology of essential hypertension and potentially open the way to pharmacologic manipulation of vasomotor activity by the use of adenosine A3 receptor agonists. PMID:26907173

  4. Ticagrelor potentiates adenosine-induced stimulation of neutrophil chemotaxis and phagocytosis.

    PubMed

    Alsharif, Khalaf F; Thomas, Mark R; Judge, Heather M; Khan, Haroon; Prince, Lynne R; Sabroe, Ian; Ridger, Victoria C; Storey, Robert F

    2015-08-01

    In the PLATO study, ticagrelor was associated with fewer pulmonary infections and subsequent deaths than clopidogrel. Neutrophils are a first-line defence against bacterial lung infection; ticagrelor inhibits cellular uptake of adenosine, a known regulator of neutrophil chemotaxis and phagocytosis. We assessed whether the inhibition of adenosine uptake by ticagrelor influences neutrophil chemotaxis and phagocytosis. Neutrophils and erythrocytes were isolated from healthy volunteers. Concentration-dependent effects of adenosine on IL-8-induced neutrophil chemotaxis were investigated and the involved receptors identified using adenosine receptor antagonists. The modulatory effects of ticagrelor on adenosine-mediated changes in neutrophil chemotaxis and phagocytosis of Streptococcus pneumoniae were determined in the presence of erythrocytes to replicate physiological conditions of cellular adenosine uptake. Low-concentration adenosine (10(-8)M) significantly increased IL-8-induced neutrophil chemotaxis (% neutrophil chemotaxis: adenosine 28.7%±4.4 vs. control 22.6%±2.4; p<0.01) by acting on the high-affinity A1 receptor. Erythrocytes attenuated the effect of adenosine, although this was preserved by ticagrelor and dipyridamole (another inhibitor of adenosine uptake) but not by control or by cangrelor. Similarly, in the presence of erythrocytes, a low concentration of adenosine (10(-8)M) significantly increased neutrophil phagocytic index compared to control when ticagrelor was present (37.6±6.6 vs. 28.0±6.6; p=0.028) but had no effect in the absence of ticagrelor. We therefore conclude that the inhibition of cellular adenosine reuptake by ticagrelor potentiates the effects of a nanomolar concentration of adenosine on neutrophil chemotaxis and phagocytosis. This represents a potential mechanism by which ticagrelor could influence host defence against bacterial lung infection. PMID:25869515

  5. Ticagrelor potentiates adenosine-induced stimulation of neutrophil chemotaxis and phagocytosis

    PubMed Central

    Alsharif, Khalaf F.; Thomas, Mark R.; Judge, Heather M.; Khan, Haroon; Prince, Lynne R.; Sabroe, Ian; Ridger, Victoria C.; Storey, Robert F.

    2015-01-01

    In the PLATO study, ticagrelor was associated with fewer pulmonary infections and subsequent deaths than clopidogrel. Neutrophils are a first-line defence against bacterial lung infection; ticagrelor inhibits cellular uptake of adenosine, a known regulator of neutrophil chemotaxis and phagocytosis. We assessed whether the inhibition of adenosine uptake by ticagrelor influences neutrophil chemotaxis and phagocytosis. Neutrophils and erythrocytes were isolated from healthy volunteers. Concentration-dependent effects of adenosine on IL-8-induced neutrophil chemotaxis were investigated and the involved receptors identified using adenosine receptor antagonists. The modulatory effects of ticagrelor on adenosine-mediated changes in neutrophil chemotaxis and phagocytosis of Streptococcus pneumoniae were determined in the presence of erythrocytes to replicate physiological conditions of cellular adenosine uptake. Low-concentration adenosine (10− 8 M) significantly increased IL-8-induced neutrophil chemotaxis (% neutrophil chemotaxis: adenosine 28.7% ± 4.4 vs. control 22.6% ± 2.4; p < 0.01) by acting on the high-affinity A1 receptor. Erythrocytes attenuated the effect of adenosine, although this was preserved by ticagrelor and dipyridamole (another inhibitor of adenosine uptake) but not by control or by cangrelor. Similarly, in the presence of erythrocytes, a low concentration of adenosine (10− 8 M) significantly increased neutrophil phagocytic index compared to control when ticagrelor was present (37.6 ± 6.6 vs. 28.0 ± 6.6; p = 0.028) but had no effect in the absence of ticagrelor. We therefore conclude that the inhibition of cellular adenosine reuptake by ticagrelor potentiates the effects of a nanomolar concentration of adenosine on neutrophil chemotaxis and phagocytosis. This represents a potential mechanism by which ticagrelor could influence host defence against bacterial lung infection. PMID:25869515

  6. Effects of adenosine metabolism in astrocytes on central nervous system oxygen toxicity.

    PubMed

    Chen, Yu-liang; Zhang, Ya-nan; Wang, Zhong-zhuang; Xu, Wei-gang; Li, Run-ping; Zhang, Jun-dong

    2016-03-15

    Hyperbaric oxygen (HBO) is widely used in military operations, especially underwater missions. However, prolonged and continuous inhalation of HBO can cause central nervous system oxygen toxicity (CNS-OT), which greatly limits HBO's application. The regulation of astrocytes to the metabolism of adenosine is involved in epilepsy. In our study, we aimed to observe the effects of HBO exposure on the metabolism of adenosine in the brain. Furthermore, we aimed to confirm the possible mechanism underlying adenosine's mediation of the CNS-OT. Firstly, anesthetized rats exposed to 5 atm absolute HBO for 80 min. The concentrations of extracellular adenosine, ATP, ADP, and AMP were detected. Secondly, free-moving rats were exposed to HBO at the same pressure for 20 min, and the activities of 5'-nucleotidase and ADK in brain tissues were measured. For the mechanism studies, we observed the effects of a series of different doses of drugs related to adenosine metabolism on the latency of CNS-OT. Results showed HBO exposure could increase adenosine content by inhibiting ADK activity and improving 5'-nucleotidase activity. And adenosine metabolism during HBO exposure may be a protective response against HBO-induced CNS-OT. Moreover, the improvement of adenosine concentration, activation of adenosine A1R, or suppression of ADK and adenosine A2AR, which are involved in the prevention of HBO-induced CNS-OT. This is the first study to demonstrate HBO exposure regulated adenosine metabolism in the brain. Adenosine metabolism and adenosine receptors are related to HBO-induced CNS-OT development. These results will provide new potential targets for the termination or the attenuation of CNS-OT. PMID:26806404

  7. Adenosine signaling in striatal circuits and alcohol use disorders.

    PubMed

    Nam, Hyung Wook; Bruner, Robert C; Choi, Doo-Sup

    2013-09-01

    Adenosine signaling has been implicated in the pathophysiology of alcohol use disorders and other psychiatric disorders such as anxiety and depression. Numerous studies have indicated a role for A1 receptors (A1R) in acute ethanol-induced motor incoordination, while A2A receptors (A2AR) mainly regulate the rewarding effect of ethanol in mice. Recent findings have demonstrated that dampened A2AR-mediated signaling in the dorsomedial striatum (DMS) promotes ethanol-seeking behaviors. Moreover, decreased A2AR function is associated with decreased CREB activity in the DMS, which enhances goal-oriented behaviors and contributes to excessive ethanol drinking in mice. Interestingly, caffeine, the most commonly used psychoactive substance, is known to inhibit both the A1R and A2AR. This dampened adenosine receptor function may mask some of the acute intoxicating effects of ethanol. Furthermore, based on the fact that A2AR activity plays a role in goal-directed behavior, caffeine may also promote ethanol-seeking behavior. The A2AR is enriched in the striatum and exclusively expressed in striatopallidal neurons, which may be responsible for the regulation of inhibitory behavioral control over drug rewarding processes through the indirect pathway of the basal ganglia circuit. Furthermore, the antagonistic interactions between adenosine and dopamine receptors in the striatum also play an integral role in alcoholism and addiction-related disorders. This review focuses on regulation of adenosine signaling in striatal circuits and the possible implication of caffeine in goal-directed behaviors and addiction. PMID:23912595

  8. Anxiolytic activity of adenosine receptor activation in mice.

    PubMed

    Jain, N; Kemp, N; Adeyemo, O; Buchanan, P; Stone, T W

    1995-10-01

    1. Purine analogues have been examined for anxiolytic- and anxiogenic-like activity in mice, by use of the elevated plus-maze. 2. The selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) had marked anxiolytic-like activity at 10 and 50 microg kg(-1), with no effect on locomotor performance at these doses. 3. The A1 selective adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (CPX) had no significant effect on anxiety-related measures or locomotor behaviour, but blocked the anxiolytic-like activity of CPA. The hydrophilic xanthine, 8-(p-sulphophenyl) theophylline did not prevent anxiolysis by CPA. 4. Caffeine had anxiogenic-like activity at 30 mg kg(-1) which was prevented by CPA at 50 micro kg(-1). 5. The A2 receptor agonist, N6-[2-(3,5-dimethoxyphenyl)-2(2-methylphenyl)-ethyl]adenosine (DPMA) had no effect on anxiety behaviour but depressed locomotor activity at the highest dose tested of 1 mg kg(-1). The A2 receptor antagonist, 1,3-dimethyl-l-propargylxanthine (DMPX) had no effect on anxiety-related measures or locomotion and did not modify the anxiolytic-like activity of CPA. 6. Administration of DPMA in combination with anxiolytic doses of CPA prevented the anxiolytic-like activity of the latter. 7. The results suggest that the selective activation of central A1 adenosine receptors induces anxiolytic-like behaviour, while the activation of A2 sites causes locomotor depression and reduces the effects of A1 receptor activation. The absence of any effect of CPX alone suggests that the receptors involved in modulating behaviour in the elevated plus-maze in mice are not activated tonically by endogenous adenosine. PMID:8640355

  9. Anxiolytic activity of adenosine receptor activation in mice.

    PubMed Central

    Jain, N.; Kemp, N.; Adeyemo, O.; Buchanan, P.; Stone, T. W.

    1995-01-01

    1. Purine analogues have been examined for anxiolytic- and anxiogenic-like activity in mice, by use of the elevated plus-maze. 2. The selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) had marked anxiolytic-like activity at 10 and 50 microg kg(-1), with no effect on locomotor performance at these doses. 3. The A1 selective adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (CPX) had no significant effect on anxiety-related measures or locomotor behaviour, but blocked the anxiolytic-like activity of CPA. The hydrophilic xanthine, 8-(p-sulphophenyl) theophylline did not prevent anxiolysis by CPA. 4. Caffeine had anxiogenic-like activity at 30 mg kg(-1) which was prevented by CPA at 50 micro kg(-1). 5. The A2 receptor agonist, N6-[2-(3,5-dimethoxyphenyl)-2(2-methylphenyl)-ethyl]adenosine (DPMA) had no effect on anxiety behaviour but depressed locomotor activity at the highest dose tested of 1 mg kg(-1). The A2 receptor antagonist, 1,3-dimethyl-l-propargylxanthine (DMPX) had no effect on anxiety-related measures or locomotion and did not modify the anxiolytic-like activity of CPA. 6. Administration of DPMA in combination with anxiolytic doses of CPA prevented the anxiolytic-like activity of the latter. 7. The results suggest that the selective activation of central A1 adenosine receptors induces anxiolytic-like behaviour, while the activation of A2 sites causes locomotor depression and reduces the effects of A1 receptor activation. The absence of any effect of CPX alone suggests that the receptors involved in modulating behaviour in the elevated plus-maze in mice are not activated tonically by endogenous adenosine. PMID:8640355

  10. Adenosine Signaling in Striatal Circuits and Alcohol Use Disorders

    PubMed Central

    Nam, Hyung Wook; Bruner, Robert C.; Choi, Doo-Sup

    2013-01-01

    Adenosine signaling has been implicated in the pathophysiology of alcohol use disorders and other psychiatric disorders such as anxiety and depression. Numerous studies have indicated a role for A1 receptors (A1R) in acute ethanol-induced motor incoordination, while A2A receptors (A2AR) mainly regulate the rewarding effect of ethanol in mice. Recent findings have demonstrated that dampened A2AR-mediated signaling in the dorsomedial striatum (DMS) promotes ethanol-seeking behaviors. Moreover, decreased A2AR function is associated with decreased CREB activity in the DMS, which enhances goal-oriented behaviors and contributes to excessive ethanol drinking in mice. Interestingly, caffeine, the most commonly used psychoactive substance, is known to inhibit both the A1R and A2AR. This dampened adenosine receptor function may mask some of the acute intoxicating effects of ethanol. Furthermore, based on the fact that A2AR activity plays a role in goal-directed behavior, caffeine may also promote ethanol-seeking behavior. The A2AR is enriched in the striatum and exclusively expressed in striatopallidal neurons, which may be responsible for the regulation of inhibitory behavioral control over drug rewarding processes through the indirect pathway of the basal ganglia circuit. Furthermore, the antagonistic interactions between adenosine and dopamine receptors in the striatum also play an integral role in alcoholism and addiction-related disorders. This review focuses on regulation of adenosine signaling in striatal circuits and the possible implication of caffeine in goal-directed behaviors and addiction. PMID:23912595

  11. Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise.

    PubMed

    Casey, Darren P; Madery, Brandon D; Pike, Tasha L; Eisenach, John H; Dietz, Niki M; Joyner, Michael J; Wilkins, Brad W

    2009-10-01

    We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols, subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received an intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (alpha-adrenoceptor antagonist) and combined phentolamine and aminophylline administration. Forearm vascular conductance (FVC; in ml x min(-1).100 mmHg(-1)) was calculated from forearm blood flow (in ml/min) and blood pressure (in mmHg). In protocol 1, the change in FVC (DeltaFVC; change from normoxic baseline) during hypoxic exercise with saline was 172 +/- 29 and 314 +/- 34 ml x min(-1) x 100 mmHg(-1) (10% and 20%, respectively). Aminophylline administration did not affect DeltaFVC during hypoxic exercise at 10% (190 +/- 29 ml x min(-1)x100 mmHg(-1), P = 0.4) or 20% (287 +/- 48 ml x min(-1) x 100 mmHg(-1), P = 0.3). In protocol 2, DeltaFVC due to hypoxic exercise with phentolamine infusion was 313 +/- 30 and 453 +/- 41 ml x min(-1) x 100 mmHg(-1) (10% and 20% respectively). DeltaFVC was similar at 10% (352 +/- 39 ml min(-1) x 100 mmHg(-1), P = 0.8) and 20% (528 +/- 45 ml x min(-1) x 100 mmHg(-1), P = 0.2) hypoxic exercise with combined phentolamine and aminophylline. In contrast, DeltaFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans. PMID:19661449

  12. METABOLIC REGULATION OF ADENOSINE TRIPHOSPHATE SULFURYLASE IN YEAST

    PubMed Central

    de Vito, Peter C.; Dreyfuss, Jacques

    1964-01-01

    de Vito, Peter C. (Princeton University, Princeton, N.J.), and Jacques Dreyfuss. Metabolic regulation of adenosine triphosphate sulfurylase in yeast. J. Bacteriol. 88:1341–1348. 1964.—The metabolic regulation of adenosine triphosphate sulfurylase (ATP-sulfurylase) from baker's yeast was studied. The enzyme was strongly inhibited by low concentrations of adenosine-5′-phosphosulfate, 3′-phosphoadenosine-5′-phosphosulfate, and sulfide. Sulfide ion was a competitive inhibitor of ATP-sulfurylase. Cysteine, methionine, sulfite, and thiosulfate were not inhibitors of the enzyme. ATP-sulfurylase was repressed when yeast was grown in the presence of methionine, and derepressed when yeast was grown in the presence of cysteine. In contrast to these results, the enzyme sulfite reductase was repressed in cysteine-grown cells. Thus, the sulfate-reducing pathway in yeast appears to be regulated at its first step both by feedback inhibition (by sulfide) and by repression (by methionine). Other known controls in the cysteine biosynthetic pathway are discussed. PMID:14234791

  13. Identification of widespread adenosine nucleotide binding in Mycobacterium tuberculosis

    SciTech Connect

    Ansong, Charles; Ortega, Corrie; Payne, Samuel H.; Haft, Daniel H.; Chauvigne-Hines, Lacie M.; Lewis, Michael P.; Ollodart, Anja R.; Purvine, Samuel O.; Shukla, Anil K.; Fortuin, Suereta; Smith, Richard D.; Adkins, Joshua N.; Grundner, Christoph; Wright, Aaron T.

    2013-01-24

    The annotation of protein function is almost completely performed by in silico approaches. However, computational prediction of protein function is frequently incomplete and error prone. In Mycobacterium tuberculosis (Mtb), ~25% of all genes have no predicted function and are annotated as hypothetical proteins. This lack of functional information severely limits our understanding of Mtb pathogenicity. Current tools for experimental functional annotation are limited and often do not scale to entire protein families. Here, we report a generally applicable chemical biology platform to functionally annotate bacterial proteins by combining activity-based protein profiling (ABPP) and quantitative LC-MS-based proteomics. As an example of this approach for high-throughput protein functional validation and discovery, we experimentally annotate the families of ATP-binding proteins in Mtb. Our data experimentally validate prior in silico predictions of >250 ATPases and adenosine nucleotide-binding proteins, and reveal 73 hypothetical proteins as novel ATP-binding proteins. We identify adenosine cofactor interactions with many hypothetical proteins containing a diversity of unrelated sequences, providing a new and expanded view of adenosine nucleotide binding in Mtb. Furthermore, many of these hypothetical proteins are both unique to Mycobacteria and essential for infection, suggesting specialized functions in mycobacterial physiology and pathogenicity. Thus, we provide a generally applicable approach for high throughput protein function discovery and validation, and highlight several ways in which application of activity-based proteomics data can improve the quality of functional annotations to facilitate novel biological insights.

  14. Dietary intake of chromium, copper, zinc, iron, manganese, calcium and magnesium: Duplicate plate technique - Measured and derived

    SciTech Connect

    Anderson, R.A.; Bryden, N.A.; Polansky, M.M. )

    1991-03-15

    Duplicate plate technique is currently the most reliable method to measure dietary intake of nutrients. However, there is no control for alterations in the diet, conscious or subconscious, due to the collection process. Duplicate diet samples were collected by 19 adult subjects, 11 females (F) and 8 males (M), while consuming freely-chosen diets. Subjects were then placed on a controlled diet to determine actual caloric requirement. Most subjects consumed fewer calories during the freely-chosen diet collection day than their actual caloric requirement. The ratio of the determined caloric intake to the calories measured in the duplicate plate sample varied from 0.90 to 2.2. The data demonstrate that derived nutrient intake may be a better measurement of actual intake than duplicate technique alone.

  15. Calcium and Magnesium Ions Are Membrane-Active against Stationary-Phase Staphylococcus aureus with High Specificity

    PubMed Central

    Xie, Yuntao; Yang, Lihua

    2016-01-01

    Staphylococcus aureus (S. aureus) is notorious for its ability to acquire antibiotic-resistance, and antibiotic-resistant S. aureus has become a wide-spread cause of high mortality rate. Novel antimicrobials capable of eradicating S. aureus cells including antibiotic-resistant ones are thus highly desired. Membrane-active bactericides and species-specific antimicrobials are two promising sources of novel anti-infective agents for fighting against bacterial antibiotic-resistance. We herein show that Ca2+ and Mg2+, two alkaline-earth-metal ions physiologically essential for diverse living organisms, both disrupt model S. aureus membranes and kill stationary-phase S. aureus cells, indicative of membrane-activity. In contrast to S. aureus, Escherichia coli and Bacillus subtilis exhibit unaffected survival after similar treatment with these two cations, indicative of species-specific activity against S. aureus. Moreover, neither Ca2+ nor Mg2+ lyses mouse red blood cells, indicative of hemo-compatibility. This works suggests that Ca2+ and Mg2+ may have implications in targeted eradication of S. aureus pathogen including the antibiotic-resistant ones. PMID:26865182

  16. Calcium and magnesium concentrations in uterine fluid and blood serum during the estrous cycle in the bovine

    PubMed Central

    Alavi-Shoushtari, Sayed Mortaza; Asri-Rezaie, Siamak; Abedizadeh, Roya; Khaki, Amir; Pak, Mozhgan; Alizadeh, Sajad

    2012-01-01

    To investigate uterine and serum Ca++ and Mg++ variations during the estrous cycle in the bovine, 66 genital tracts and blood samples were collected from Urmia abattoir, Urmia, Iran. The phase of the estrous cycle was determined by examination of the structures present on ovaries and uterine tonicity. Of the collected samples, 17 were pro-estrus, 12 estrus, 14 metestrus and 23 diestrus. The uterine fluid was collected by gentle scraping of the uterine mucosa with a curette. The mean ± SEM concentration of serum Ca++ in pro-estrus, estrus, metestrus and diestrus was 5.77 ± 0.69, 8.87 ± 1.83, 10.95 ± 1.52, 11.09 ± 1.08 mg dL-1, and the mean concentration of uterine fluid Ca++ was 4.40 ± 0.72, 3.15 ± 0.67, 5.89 ± 0.88, 8.63 ± 0.97 mg dL-1, respectively. The mean concentration of serum Mg++ in pro-estrus, estrus, metestrus and diestrus was 3.53 ± 0.30, 4.20 ± 0.52, 3.49 ± 0.38, 3.39 ± 0.29 mg dL-1, and mean concentration of uterine fluid Mg++ was 5.27 ± 0.42, 4.92 ± 0.60, 5.56 ± 0.30, 5.88 ± 0.36 mg dL-1, respectively. The serum and uterine fluid Ca++ in pro-estrus were significantly different from those of the metestrus and diestrus. In all stages of estrous cycle the mean concentration of serum Ca++ was higher than that in the uterine fluid. The difference between serum and uterine fluid Ca++ in estrus, metestrus and diestrus was significant. There was no significant difference between serum Mg++ content nor was it different from uterine fluid Mg++ content at any stages of estrous cycle. In all stages of estrous cycle the uterine fluid Mg++ was higher than that of the serum. These results suggest that during the estrous cycle in the cow, Ca++ is passively secreted in uterine fluids and is mostly dependent on blood serum Ca++ variations but Mg++ is secreted independently and does not follow variations in the serum concentrations. PMID:25653760

  17. Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women.

    PubMed

    Holloway, Leah; Moynihan, Sharon; Abrams, Steven A; Kent, Kyla; Hsu, Andrew R; Friedlander, Anne L

    2007-02-01

    Deficiency of oestrogen at menopause decreases intestinal Ca absorption, contributing to a negative Ca balance and bone loss. Mg deficiency has also been associated with bone loss. The purpose of the present investigation was to test the hypothesis that treatment with a spray-dried mixture of chicory oligofructose and long-chain inulin (Synergy1; SYN1) would increase the absorption of both Ca and Mg and alter markers of bone turnover. Fifteen postmenopausal women (72.2 (SD 6.4) years) were treated with SYN1 or placebo for 6 weeks using a double-blind, placebo-controlled, cross-over design. Fractional Ca and Mg absorption were measured using dual-tracer stable isotopes before and after treatment. Bone turnover markers were measured at baseline, 3 and 6 weeks. Fractional absorption of Ca and Mg increased following SYN1 compared with placebo (P < 0.05). Bone resorption (by urinary deoxypyridinoline cross-links) was greater than baseline at 6 weeks of active treatment (P < 0.05). Bone formation (by serum osteocalcin) showed an upward trend at 3 weeks and an increase following 6 weeks of SYN1 (P < 0.05). Closer examination revealed a variation in response, with two-thirds of the subjects showing increased absorption with SYN1. Post hoc analyses demonstrated that positive responders had significantly lower lumbar spine bone mineral density than non-responders (dual X-ray absorptiometry 0.887 +/- 0.102 v. 1.104 +/- 0.121 g/cm2; P < 0.01), and changes in bone turnover markers occurred only in responders. These results suggest that 6 weeks of SYN1 can improve mineral absorption and impact markers of bone turnover in postmenopausal women. Further research is needed to determine why a greater response was found in women with lower initial spine bone mineral density. PMID:17298707

  18. Evaluation of the content and bioaccessibility of iron, zinc, calcium and magnesium from groats, rice, leguminous grains and nuts.

    PubMed

    Suliburska, Joanna; Krejpcio, Zbigniew

    2014-03-01

    The objective of this study was to determine the content and the bioaccessibility of minerals (Fe, Zn, Ca and Mg) in commonly consumed food products, such as cereal groats, rice, leguminous grains and nuts purchased from the local market. The contents of Fe, Zn, Ca and Mg in foods were assayed after dry ashing of samples, while the bioaccessibility of these minerals after enzymatic in vitro digestion, was determined by flame atomic absorption spectrometry. A relatively high content of Fe was found in cashew nuts and green lentils, while cashew nuts and buckwheat groats had the highest concentration of Zn. It was found that the highest amount of macro-elements was generally in nuts, in particular: brazil nuts (Ca and Mg), cashews (Mg) and hazelnuts (Ca and Mg). Concerning the mineral bioaccessibility, the highest values for Fe were obtained in cashew nuts and green lentils (2.8 and 1.7 mg/100 g), for Zn in green lentils (2.1 mg/100 g), for Ca in brazil nuts and shelled pea (32.6 and 29.1 mg/100 g), while for Mg in shelled peas and green lentils (43.4 and 33.9 mg/100 g). Generally, the best sources of bioaccessible minerals seem to be leguminous grains and nuts. PMID:24587537

  19. Calcium and magnesium concentrations in uterine fluid and blood serum during the estrous cycle in the bovine.

    PubMed

    Alavi-Shoushtari, Sayed Mortaza; Asri-Rezaie, Siamak; Abedizadeh, Roya; Khaki, Amir; Pak, Mozhgan; Alizadeh, Sajad

    2012-01-01

    To investigate uterine and serum Ca(++) and Mg(++) variations during the estrous cycle in the bovine, 66 genital tracts and blood samples were collected from Urmia abattoir, Urmia, Iran. The phase of the estrous cycle was determined by examination of the structures present on ovaries and uterine tonicity. Of the collected samples, 17 were pro-estrus, 12 estrus, 14 metestrus and 23 diestrus. The uterine fluid was collected by gentle scraping of the uterine mucosa with a curette. The mean ± SEM concentration of serum Ca(++) in pro-estrus, estrus, metestrus and diestrus was 5.77 ± 0.69, 8.87 ± 1.83, 10.95 ± 1.52, 11.09 ± 1.08 mg dL(-1), and the mean concentration of uterine fluid Ca(++) was 4.40 ± 0.72, 3.15 ± 0.67, 5.89 ± 0.88, 8.63 ± 0.97 mg dL(-1), respectively. The mean concentration of serum Mg(++) in pro-estrus, estrus, metestrus and diestrus was 3.53 ± 0.30, 4.20 ± 0.52, 3.49 ± 0.38, 3.39 ± 0.29 mg dL(-1), and mean concentration of uterine fluid Mg(++) was 5.27 ± 0.42, 4.92 ± 0.60, 5.56 ± 0.30, 5.88 ± 0.36 mg dL(-1), respectively. The serum and uterine fluid Ca(++) in pro-estrus were significantly different from those of the metestrus and diestrus. In all stages of estrous cycle the mean concentration of serum Ca(++) was higher than that in the uterine fluid. The difference between serum and uterine fluid Ca(++) in estrus, metestrus and diestrus was significant. There was no significant difference between serum Mg(++) content nor was it different from uterine fluid Mg(++) content at any stages of estrous cycle. In all stages of estrous cycle the uterine fluid Mg(++) was higher than that of the serum. These results suggest that during the estrous cycle in the cow, Ca(++) is passively secreted in uterine fluids and is mostly dependent on blood serum Ca(++) variations but Mg(++) is secreted independently and does not follow variations in the serum concentrations. PMID:25653760

  20. Estimation of calcified tissues hardness via calcium and magnesium ionic to atomic line intensity ratio in laser induced breakdown spectra

    NASA Astrophysics Data System (ADS)

    Abdel-Salam, Z. A.; Galmed, A. H.; Tognoni, E.; Harith, M. A.

    2007-12-01

    Calcified tissues representing three different matrices, namely enamel of human teeth, shells and eggshell, have been studied via Laser Induced Breakdown Spectroscopy (LIBS) technique. The experimental CaII/CaI and MgII/MgI ratios have been measured, in view of the expected correlation between the extent of ionization caused by the laser induced shock wave (SW) and the hardness of the target. The ratio CaII/CaI between the ionic calcium line at 373.69 nm and the neutral line at 428.9 nm is obtained for enamel, shells and eggshell spectra, as well as the ratio MgII/MgI between the ionic magnesium line at 280.26 nm and the neutral line at 285.22 nm. The results show that such spectral lines intensities ratio differs for different matrices and is indeed related to the target materials hardness. It is also found that the MgII/MgI ratio is preferable as an indicator of hardness since these lines are less affected by self absorption. The SW front speed has been measured in the three cases and the obtained values confirm the proportionality to the target hardness. The results here obtained suggest the feasibility of the quantitative estimation of hardness for any other calcified tissues.

  1. Individual effects of sodium, potassium, calcium, and magnesium chloride salts on Lactobacillus pentosus and Saccharomyces cerevisiae growth.

    PubMed

    Bautista-Gallego, J; Arroyo-López, F N; Durán-Quintana, M C; Garrido-Fernandez, A

    2008-07-01

    A quantitative investigation on the individual effects of sodium (NaCl), potassium (KCl), calcium (CaCl2), and magnesium (MgCl2) chloride salts against Lactobacillus pentosus and Saccharomyces cerevisiae, two representative microorganisms of table olives and other fermented vegetables, was carried out. In order to assess their potential activities, both the kinetic growth parameters and dose-response profiles in synthetic media (deMan Rogosa Sharpe broth medium and yeast-malt-peptone-glucose broth medium, respectively) were obtained and analyzed. Microbial growth was monitored via optical density measurements as a function of contact time in the presence of progressive chloride salt concentrations. Relative maximum specific growth rate and lag-phase period were modeled as a function of the chloride salt concentrations. Moreover, for each salt and microorganism tested, the noninhibitory concentrations and the MICs were estimated and compared. All chloride salts exerted a significant antimicrobial effect on the growth cycle; particularly, CaCl2 showed a similar effect to NaCl, while KCl and MgCl2 were progressively less inhibitory. Microbial susceptibility and resistance were found to be nonlinearly dose related. PMID:18680941

  2. Effects of calcium and magnesium hardness on the fertilization and hatching success of channel X blue hybrid catfish eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aquifer used for hybrid catfish hatcheries is less than 10 mg/L of calcium hardness and 1- 25 mg/L of magnesium hardness. Embryonic development is deemed to be the most sensitive stage in the life cycle of a teleost. As egg development takes outside the fish’s body, water hardness is one abioti...

  3. Reactions Involving Calcium and Magnesium Sulfates as Potential Sources of Sulfur Dioxide During MSL SAM Evolved Gas Analyses

    NASA Technical Reports Server (NTRS)

    McAdam, A. C.; Knudson, C. A.; Sutter, B.; Franz, H. B.; Archer, P. D., Jr.; Eigenbrode, J. L.; Ming, D. W.; Morris, R. V.; Hurowitz, J. A.; Mahaffy, P. R.; Navarro-Gonzalez, R.

    2016-01-01

    The Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments on the Mars Science Laboratory (MSL) have analyzed several subsamples of <150 micron fines from ten sites at Gale Crater. Three were in Yellowknife Bay: the Rocknest aeolian bedform (RN) and drilled Sheepbed mudstone from sites John Klein (JK) and Cumberland (CB). One was drilled from the Windjana (WJ) site on a sandstone of the Kimberly formation. Four were drilled from sites Confidence Hills (CH), Mojave (MJ), Telegraph Peak (TP) and Buckskin (BK) of the Murray Formation at the base of Mt. Sharp. Two were drilled from sandstones of the Stimson formation targeting relatively unaltered (Big Sky, BY) and then altered (Greenhorn, GH) material associated with a light colored fracture zone. CheMin analyses provided quantitative sample mineralogy. SAM's evolved gas analysis mass spectrometry (EGA-MS) detected H2O, CO2, O2, H2, SO2, H2S, HCl, NO, and other trace gases. This contribution will focus on evolved SO2. All samples evolved SO2 above 500 C. The shapes of the SO2 evolution traces with temperature vary between samples but most have at least two "peaks' within the wide high temperature evolution, from approx. 500-700 and approx. 700-860 C (Fig. 1). In many cases, the only sulfur minerals detected with CheMin were Ca sulfates (e.g., RN and GH), which should thermally decompose at temperatures above those obtainable by SAM (>860 C). Sulfides or Fe sulfates were detected by CheMin (e.g., CB, MJ, BK) and could contribute to the high temperature SO2 evolution, but in most cases they are not present in enough abundance to account for all of the SO2. This additional SO2 could be largely associated with x-ray amorphous material, which comprises a significant portion of all samples. It can also be attributed to trace S phases present below the CheMin detection limit, or to reactions which lower the temperatures of SO2 evolution from sulfates that are typically expected to thermally decompose at temperatures outside the SAM temperature range (e.g., Ca and Mg sulfates). Here we discuss the results of SAM-like laboratory analyses targeted at understanding this last possibility, focused on understanding if reactions of HCl or an HCl evolving phase (oxychlorine phases, chlorides, etc.) and Ca and Mg sulfates can result in SO2 evolution in the SAM temperature range.

  4. Removal of hardness agents, calcium and magnesium, by natural and alkaline modified pumice stones in single and binary systems

    NASA Astrophysics Data System (ADS)

    Sepehr, Mohammad Noori; Zarrabi, Mansur; Kazemian, Hossein; Amrane, Abdeltif; Yaghmaian, Kamiar; Ghaffari, Hamid Reza

    2013-06-01

    Natural and alkaline modified pumice stones were used for the adsorption of water hardening cations, Ca2+ and Mg2+. The adsorbents were characterized using XRF, XRD, SEM and FTIR instrumental techniques. At equilibrium time and for 150 mg/L of a given cation, removal efficiencies were 83% and 94% for calcium and 48% and 73% for magnesium for raw and modified pumices, respectively. The optimal pH for raw and modified pumices were found to be 6.0, leading to the removal of 79 and 96% of calcium and 51 and 93% of magnesium by 10 g/L of raw and modified pumice adsorbents, respectively. Maximum adsorption capacities were 57.27 and 62.34 mg/g for Ca2+ and 44.53 and 56.11 mg/g for Mg2+ on the raw and modified pumices, respectively. Ca2+ and Mg2+ adsorption capacities of the pumice adsorbents decreased in the presence of competing cations. Less than 300 min were needed to achieve 99 and 92% desorption of the adsorbed Ca2+ and 100 and 89% of the adsorbed Mg2+ from the natural and modified pumices, respectively. After treating synthetic water solution simulating an actual water stream with the alkali-modified pumice, total hardness of the treated sample met the required standard for drinking water, namely below 300 mg/L of CaCO3 (297.5 mg/L). The studied pumice adsorbents, and especially the treated pumice, can be therefore considered as promising low cost adsorbents, suitable for the removal of hardness ions from drinking water.

  5. Evaluation of calcium and magnesium in scalp hair samples of population consuming different drinking water: risk of kidney stone.

    PubMed

    Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Shaikh, Haffeezur Rehman; Arain, Salma Aslam; Arain, Sadaf Sadia; Brahman, Kapil Dev

    2013-12-01

    The objective of this study was to examine the relationship between calcium (Ca) and magnesium (Mg) in underground water (UGW), bottled mineral water (BMW), and domestic treated water (DTW) with related to risk of kidney stones. The water samples were collected from different areas of Sindh, Pakistan. The scalp hair samples of both genders, age ranged 30-60 years, consuming different types of water, have or have not kidney disorders, were selected. The Ca and Mg concentrations were determined in scalp hair of study subjects and water by flame atomic absorption spectroscopy. The Ca and Mg contents in different types of drinking water, UGW, DTW, and BMW, were found in the range of 79.1-466, 23.7-140, and 45-270 mg/L and 4.43-125, 5.23-39.6, and 7.16-51.3 mg/L, respectively. It was observed that Ca concentration in the scalp hair samples of kidney stone patients consuming different types of drinking water was found to be higher (2,895-4721 μg/g) while Mg level (84.3-101 μg/g) was lower as compare to referents subjects (2,490-2,730 μg/g for Ca, 107-128 μg/g for Mg) in both genders. The positive correlation was found between Ca and Mg levels in water with related to kidney stone formations in population, especially who consumed underground water. A relative risk and odd ratio were calculated; the relative risk had a strong positive association with incidence of kidney stone which depends on types of drinking water. PMID:24218227

  6. Seasonal patterns of nitrogen, phosphorus, potassium, calcium and magnesium in the leaves of the Massachusetts cranberry. [Vaccinium macrocarpon

    SciTech Connect

    DeMoranville, C.J.; Deubert, K.H.

    1986-01-01

    Leaf samples from cranberry plants in Wareham, MA, were collected during the 1980-82 growing seasons and analyzed for N, P, K, Ca and Mg. The seasonal patterns which emerged allowed the proposal of normal ranges for the elements and optimum times for sampling. The foliar nutrient levels obtained were compared to those for cranberries grown in other areas as well as to those for crops which are grown under similar conditions.

  7. Effects of calcium and magnesium on the frequency of miniature end-plate potentials during prolonged tetanization

    PubMed Central

    Hurlbut, W. P.; Longenecker, H. B.; Mauro, Alexander

    1971-01-01

    1. End-plate potentials (e.p.p.s) and miniature end-plate potentials (min.e.p.p.s) were recorded intracellularly from the cutaneous pectoris nerve-muscle preparation of the frog during prolonged stimulation at low frequencies (5/sec—50/sec). 2. When Ca was present in the bathing solution, the quantum content of the e.p.p. and the frequency of occurrence of the min.e.p.p.s gradually increased during the period of stimulation. During the first few minutes of stimulation, the min.e.p.p. frequency increased linearly with time, and the rate of increase was dependent on the Ca concentration of the bathing solution. However, Mg had no effect on this Ca-dependent increase in min.e.p.p. frequency. 3. A large maintained increase in min.e.p.p. frequency also occurred during prolonged stimulation in solutions that contained no added Ca and 1-2 mM-EGTA. Under these conditions the increase in min.e.p.p. frequency was dependent on the Mg concentration of the bathing solution and was exponential in time. 4. It is suggested that the rise in min.e.p.p. frequency is caused by an accumulation of Ca or Mg ions in the nerve terminal, and it is suggested that these ions enter the terminal at relatively non-specific sites distinct from the Ca-specific sites that trigger the `phasic' release of transmitter. PMID:5316661

  8. Evaluation of postmortem serum calcium and magnesium levels in relation to the causes of death in forensic autopsy.

    PubMed

    Zhu, Bao-Li; Ishikawa, Takaki; Quan, Li; Li, Dong-Ri; Zhao, Dong; Michiue, Tomomi; Maeda, Hitoshi

    2005-12-01

    There appears to be very poor investigation of postmortem serum calcium (Ca) and magnesium (Mg) for diagnostic evidence to determine the cause of death. The aim of the present study was a comprehensive analysis of the serum levels in relation to the causes of death in routine casework. Autopsy cases (total, n=360; 5-48 h postmortem), including blunt injury (n=76), sharp injury (n=29), asphyxiation (n=42), drownings (n=28: freshwater, n=11; saltwater, n=17), fire fatalities (n=79), methamphetamine (MA) poisoning (n=8), delayed death from traumas (n=37), and acute myocardial infarction/ischemia (AMI, n=61), were examined. In total cases, there was no significant postmortem time-dependent rise in serum Ca and Mg. Both Ca and Mg levels in the heart and peripheral blood were significantly higher in saltwater drowning compared with those of the other groups. In addition, a significant elevation in the Ca level was observed in freshwater drowning and fire fatalities, and in the Mg level in fatal MA intoxication and asphyxiation. Topographic analyses suggested a rise in serum Ca and Mg due to aspirated saltwater in drowning, that in serum Ca in freshwater drowning and fire fatalities of peripheral skeletal muscle origin and that in serum Mg in MA fatality and asphyxiation of myocardial and/or peripheral origin. These markers may be useful especially for diagnosis and differentiation of salt- and freshwater drownings and may be also helpful to determine the causes of death involving skeletal muscle damage, including burns and MA intoxication. PMID:16216707

  9. Intravenous Calcium and Magnesium for Oxaliplatin-Induced Sensory Neurotoxicity in Adjuvant Colon Cancer: NCCTG N04C7

    PubMed Central

    Grothey, Axel; Nikcevich, Daniel A.; Sloan, Jeff A.; Kugler, John W.; Silberstein, Peter T.; Dentchev, Todor; Wender, Donald B.; Novotny, Paul J.; Chitaley, Umesh; Alberts, Steven R.; Loprinzi, Charles L.

    2011-01-01

    Purpose Cumulative sensory neurotoxicity (sNT) is the dose-limiting toxicity of oxaliplatin, which commonly leads to early discontinuation of oxaliplatin-based therapy in the palliative and adjuvant settings. In a nonrandomized, retrospective study, intravenous (IV) calcium/magnesium (Ca/Mg) was associated with reduced oxaliplatin-induced sNT. Methods Patients with colon cancer undergoing adjuvant therapy with infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) were randomly assigned to Ca/Mg (1g calcium gluconate plus 1g magnesium sulfate pre- and post-oxaliplatin) or placebo, in a double-blinded manner. The primary end point was the percentage of patients with grade 2 or greater sNT at any time during or after oxaliplatin-based therapy by National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE; version 3) criteria. An oxaliplatin-specific sNT scale and patient questionnaires were also used to assess sNT. After 104 of 300 planned patients were enrolled, the study was closed. This was due to preliminary reports from another trial that suggested that Ca/Mg decreased treatment efficacy; these data were subsequently found to be incorrect. Results Overall, 102 patients were available for analysis. Ca/Mg decreased the incidence of chronic, cumulative, grade 2 or greater sNT, as measured by NCI CTCAE (P = .038) and also by the oxaliplatin-specific sNT scale (P = .018). In addition, acute muscle spasms associated with oxaliplatin were significantly reduced (P = .01) No effect on acute, cold-induced sNT was found. No substantial differences in adverse effects were noted between Ca/Mg and placebo. Conclusion Despite early termination and decreased statistical power, this study supports IV Ca/Mg as an effective neuroprotectant against oxaliplatin-induced cumulative sNT in adjuvant colon cancer. PMID:21189381

  10. Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Deficiency of oestrogen at menopause decreases intestinal Ca absorption, contributing to a negative Ca balance and bone loss. Mg deficiency has also been associated with bone loss. The purpose of the present investigation was to test the hypothesis that treatment with a spray-dried mixture of chicor...

  11. Adenosine 5′-monophosphate ameliorates D-galactosamine/lipopolysaccharide-induced liver injury through an adenosine receptor-independent mechanism in mice

    PubMed Central

    Zhan, Y; Wang, Z; Yang, P; Wang, T; Xia, L; Zhou, M; Wang, Y; Wang, S; Hua, Z; Zhang, J

    2014-01-01

    D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced lethality and acute liver failure is dependent on endogenously produced inflammatory cytokines. Adenosine has been proven to be a central role in the regulation of inflammatory response. It is not entirely clear that which adenosine action is actually crucial to limiting inflammatory tissue destruction. Here we showed that GalN/LPS challenge elevated hepatic adenosine and induced lethality in adenosine receptor-deficient mice with equal efficiency as wild-type mice. In GalN/LPS-treated mice, pretreatment with adenosine 5′-monophosphate (5′-AMP) significantly elevated hepatic adenosine level and reduced mortality through decreasing cytokine and chemokine production. In RAW264.7 cells, 5′-AMP treatment inhibited the production of inflammatory cytokines, which is not mediated through adenosine receptors. 5′-AMP failed to attenuate LPS-induced nuclear factor-κB (NF-κB) p65 nuclear translocation, but reduced LPS-induced recruitment of NF-κB p65 to inflammatory gene promoters and decreased LPS-induced enrichment of H3K4 dimethylation at the tumor necrosis factor-α (TNF-α) promoter, which was involved in 5′-AMP-induced elevation of cellular adenosine and a decline of methylation potential. In vitro biochemical analysis revealed that adenosine directly attenuated recruitment of NF-κB to the TNF-α and interleukin-6 promoters. Our findings demonstrate that 5′-AMP-inhibiting inflammatory response is not mediated by adenosine receptors and it may represent a potential protective agent for amelioration of LPS-induced liver injury. PMID:24407238

  12. Genetic removal of the A2A adenosine receptor enhances pulmonary inflammation, mucin production, and angiogenesis in adenosine deaminase-deficient mice.

    PubMed

    Mohsenin, Amir; Mi, Tiejuan; Xia, Yang; Kellems, Rodney E; Chen, Jiang-Fan; Blackburn, Michael R

    2007-09-01

    Adenosine is generated at sites of tissue injury where it serves to regulate inflammation and damage. Adenosine signaling has been implicated in the regulation of pulmonary inflammation and damage in diseases such as asthma and chronic obstructive pulmonary disease; however, the contribution of specific adenosine receptors to key immunoregulatory processes in these diseases is still unclear. Mice deficient in the purine catabolic enzyme adenosine deaminase (ADA) develop pulmonary inflammation and mucous metaplasia in association with adenosine elevations making them a useful model for assessing the contribution of specific adenosine receptors to adenosine-mediated pulmonary disease. Studies suggest that the A(2A) adenosine receptor (A(2A)R) functions to limit inflammation and promote tissue protection; however, the contribution of A(2A)R signaling has not been examined in the ADA-deficient model of adenosine-mediated lung inflammation. The purpose of the current study was to examine the contribution of A(2A)R signaling to the pulmonary phenotype seen in ADA-deficient mice. This was accomplished by generating ADA/A(2A)R double knockout mice. Genetic removal of the A(2A)R from ADA-deficient mice resulted in enhanced inflammation comprised largely of macrophages and neutrophils, mucin production in the bronchial airways, and angiogenesis, relative to that seen in the lungs of ADA-deficient mice with the A(2A)R. In addition, levels of the chemokines monocyte chemoattractant protein-1 and CXCL1 were elevated, whereas levels of cytokines such as TNF-alpha and IL-6 were not. There were no compensatory changes in the other adenosine receptors in the lungs of ADA/A(2A)R double knockout mice. These findings suggest that the A(2A)R plays a protective role in the ADA-deficient model of pulmonary inflammation. PMID:17601796

  13. [Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

    PubMed

    Bagrov, Ia Iu; Manusova, N B

    2014-01-01

    Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms. PMID:25509166

  14. Sustained Elevated Adenosine via ADORA2B Promotes Chronic Pain through Neuro-immune Interaction.

    PubMed

    Hu, Xia; Adebiyi, Morayo G; Luo, Jialie; Sun, Kaiqi; Le, Thanh-Thuy T; Zhang, Yujin; Wu, Hongyu; Zhao, Shushan; Karmouty-Quintana, Harry; Liu, Hong; Huang, Aji; Wen, Yuan Edward; Zaika, Oleg L; Mamenko, Mykola; Pochynyuk, Oleh M; Kellems, Rodney E; Eltzschig, Holger K; Blackburn, Michael R; Walters, Edgar T; Huang, Dong; Hu, Hongzhen; Xia, Yang

    2016-06-28

    The molecular mechanisms of chronic pain are poorly understood and effective mechanism-based treatments are lacking. Here, we report that mice lacking adenosine deaminase (ADA), an enzyme necessary for the breakdown of adenosine, displayed unexpected chronic mechanical and thermal hypersensitivity due to sustained elevated circulating adenosine. Extending from Ada(-/-) mice, we further discovered that prolonged elevated adenosine contributed to chronic pain behaviors in two additional independent animal models: sickle cell disease mice, a model of severe pain with limited treatment, and complete Freund's adjuvant paw-injected mice, a well-accepted inflammatory model of chronic pain. Mechanistically, we revealed that activation of adenosine A2B receptors on myeloid cells caused nociceptor hyperexcitability and promoted chronic pain via soluble IL-6 receptor trans-signaling, and our findings determined that prolonged accumulated circulating adenosine contributes to chronic pain by promoting immune-neuronal interaction and revealed multiple therapeutic targets. PMID:27320922

  15. 2-Triazole-Substituted Adenosines: A New Class of Selective A3 Adenosine Receptor Agonists, Partial Agonists, and Antagonists

    PubMed Central

    Cosyn, Liesbet; Palaniappan, Krishnan K.; Kim, Soo-Kyung; Duong, Heng T.; Gao, Zhan-Guo; Jacobson, Kenneth A.; Van Calenbergh, Serge

    2016-01-01

    “Click chemistry” was explored to synthesize two series of 2-(1,2,3-triazolyl)adenosine derivatives (1–14). Binding affinity at the human A1, A2A, and A3ARs (adenosine receptors) and relative efficacy at the A3AR were determined. Some triazol-1-yl analogues showed A3AR affinity in the low nanomolar range, a high ratio of A3/A2A selectivity, and a moderate-to-high A3/A1 ratio. The 1,2,3-triazol-4-yl regiomers typically showed decreased A3AR affinity. Sterically demanding groups at the adenine C2 position tended to reduce relative A3AR efficacy. Thus, several 5′-OH derivatives appeared to be selective A3AR antagonists, i.e., 10, with 260-fold binding selectivity in comparison to the A1AR and displaying a characteristic docking mode in an A3AR model. The corresponding 5′-ethyluronamide analogues generally showed increased A3AR affinity and behaved as full agonists, i.e., 17, with 910-fold A3/A1 selectivity. Thus, N6-substituted 2-(1,2,3-triazolyl)-adenosine analogues constitute a novel class of highly potent and selective nucleoside-based A3AR antagonists, partial agonists, and agonists. PMID:17149867

  16. PAP and NT5E inhibit nociceptive neurotransmission by rapidly hydrolyzing nucleotides to adenosine

    PubMed Central

    2011-01-01

    Background Prostatic acid phosphatase (PAP) and ecto-5'-nucleotidase (NT5E, CD73) produce extracellular adenosine from the nucleotide AMP in spinal nociceptive (pain-sensing) circuits; however, it is currently unknown if these are the main ectonucleotidases that generate adenosine or how rapidly they generate adenosine. Results We found that AMP hydrolysis, when measured histochemically, was nearly abolished in dorsal root ganglia (DRG) neurons and lamina II of spinal cord from Pap/Nt5e double knockout (dKO) mice. Likewise, the antinociceptive effects of AMP, when combined with nucleoside transport inhibitors (dipyridamole or 5-iodotubericidin), were reduced by 80-100% in dKO mice. In addition, we used fast scan cyclic voltammetry (FSCV) to measure adenosine production at subsecond resolution within lamina II. Adenosine was maximally produced within seconds from AMP in wild-type (WT) mice but production was reduced >50% in dKO mice, indicating PAP and NT5E rapidly generate adenosine in lamina II. Unexpectedly, we also detected spontaneous low frequency adenosine transients in lamina II with FSCV. Adenosine transients were of short duration (<2 s) and were reduced (>60%) in frequency in Pap-/-, Nt5e-/- and dKO mice, suggesting these ectonucleotidases rapidly hydrolyze endogenously released nucleotides to adenosine. Field potential recordings in lamina II and behavioral studies indicate that adenosine made by these enzymes acts through the adenosine A1 receptor to inhibit excitatory neurotransmission and nociception. Conclusions Collectively, our experiments indicate that PAP and NT5E are the main ectonucleotidases that generate adenosine in nociceptive circuits and indicate these enzymes transform pulsatile or sustained nucleotide release into an inhibitory adenosinergic signal. PMID:22011440

  17. Regulation by equilibrative nucleoside transporter of adenosine outward currents in adult rat spinal dorsal horn neurons.

    PubMed

    Liu, Tao; Fujita, Tsugumi; Kawasaki, Yasuhiko; Kumamoto, Eiichi

    2004-07-30

    A current response induced by superfusing adenosine was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. In 78% of the neurons examined, adenosine induced an outward current at -70 mV [18.8 +/- 1.1 pA (n = 98) at 1mM] in a dose-dependent manner (EC(50) = 177 microM). A similar current was induced by A(1) agonist N(6)-cyclopentyladenosine (1 microM), whereas A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (1 microM) reversed the adenosine action. The adenosine current reversed its polarity at a potential being close to the equilibrium potential for K(+), and was attenuated by Ba(2+) (100 microM) and 4-aminopyridine (5mM) but not tetraethylammonium (5mM). The adenosine current was enhanced in duration by equilibrative nucleoside-transport (rENT1) inhibitor S-(4-nitrobenzyl)-6-thioinosine (1 microM) and adenosine deaminase (ADA) inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (1 microM), and slowed in falling phase by adenosine kinase (AK) inhibitor iodotubercidine (1 microM). We conclude that a Ba(2+)- and 4-aminopyridine-sensitive K(+) channel in SG neurons is opened via the activation of A(1) receptors by adenosine whose level is possibly regulated by rENT1, adenosine deaminase and adenosine kinase. Considering that intrathecally-administered adenosine analogues produce antinociception, the regulatory systems of adenosine may serve as targets for antinociceptive drugs. PMID:15275960

  18. Estimation of skeletal muscle interstitial adenosine during forearm dynamic exercise in humans

    NASA Technical Reports Server (NTRS)

    Costa, F.; Heusinkveld, J.; Ballog, R.; Davis, S.; Biaggioni, I.

    2000-01-01

    It has been proposed that adenosine is a metabolic signal that triggers activation of muscle afferents involved in the exercise pressor reflex. Furthermore, exogenous adenosine induces sympathetic activation that mimics the exercise pressor reflex, and blockade of adenosine receptors inhibits sympathetic activation induced by exercise. Thus, we hypothesize that adenosine is released locally by the muscle during exercise. We used microdialysis probes, placed in the flexor digitorium superficialis muscle, to estimate muscle interstitial adenosine levels in humans. We estimated resting in vivo muscle interstitial adenosine concentrations (0.292+/-0.058 micromol/L, n=4) by perfusing increasing concentrations of adenosine to determine the gradient produced in the dialysate. Muscle interstitial adenosine concentrations increased from 0.23+/-0.04 to 0.82+/-0.14 micromol/L (n=14, P<0.001) during intermittent dynamic exercise at 50% of maximal voluntary contraction. Lactate increased from 0.8+/-0.1 to 2.3+/-0.3 mmol/L (P<0.001). Lower intensity (15% maximal voluntary contraction) intermittent dynamic exercise increased adenosine concentrations from 0.104+/-0.02 to 0.42+/-0.16 micromol/L (n=7). The addition of ischemia to this low level of exercise produced a greater increase in adenosine (from 0.095+/-0.02 to 0.48+/-0.2 micromol/L) compared with nonischemic exercise (0. 095+/-0.02 to 0.25+/-0.12 micromol/L). These results indicate that microdialysis is useful in estimating adenosine concentrations and in reflecting changes in muscle interstitial adenosine during dynamic exercise in humans.

  19. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    PubMed Central

    Chee, Hyun Keun

    2013-01-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands. PMID:24465242

  20. Adenosine A2A receptor dynamics studied with the novel fluorescent agonist Alexa488-APEC

    PubMed Central

    Brand, Frank; Klutz, Athena; Jacobson, Kenneth A.; Fredholm, Bertil B.; Schulte, Gunnar

    2009-01-01

    G protein-coupled receptors, such as the adenosine A2A receptor, are dynamic proteins, which undergo agonist-dependent redistribution from the cell surface to intracellular membranous compartments, such as endosomes. In order to study the kinetics of adenosine A2A receptor redistribution in living cells, we synthesized a novel fluorescent agonist, Alexa488-APEC. Alexa488-APEC binds to adenosine A2A (Ki = 149 ± 27 nM) as well as A3 receptors (Ki= 240 ± 160 nM) but not to adenosine A1 receptors. Further, we characterized the dose-dependent increase in Alexa488-APEC-induced cAMP production as well as cAMP response element binding (CREB) protein phosphorylation, verifying the ligand’s functionality at adenosine A2A but not A2B receptors. In live cell imaging studies, Alexa488-APEC induced adenosine A2A receptor internalization, which was blocked by the competitive reversible antagonist ZM 241385 and hyperosmolaric sucrose. Further, internalized adenosine A2A receptors co-localized with clathrin and Rab5, indicating that agonist stimulation promotes adenosine A2A receptor uptake through a clathrin-dependent mechanism to Rab5-positive endosomes. The basic characterization of Alexa488-APEC provided here showed that it provides a usefultool for tracing adenosine A2A receptors in vitro. PMID:18603240

  1. Clearance of rapid adenosine release is regulated by nucleoside transporters and metabolism.

    PubMed

    Nguyen, Michael D; Ross, Ashley E; Ryals, Matthew; Lee, Scott T; Venton, B Jill

    2015-12-01

    Adenosine is a neuromodulator that regulates neurotransmission in the brain and central nervous system. Recently, spontaneous adenosine release that is cleared in 3-4 sec was discovered in mouse spinal cord slices and anesthetized rat brains. Here, we examined the clearance of spontaneous adenosine in the rat caudate-putamen and exogenously applied adenosine in caudate brain slices. The V max for clearance of exogenously applied adenosine in brain slices was 1.4 ± 0.1 μmol/L/sec. In vivo, the equilibrative nucleoside transport 1 (ENT1) inhibitor, S-(4-nitrobenzyl)-6-thioinosine (NBTI) (1 mg/kg, i.p.) significantly increased the duration of adenosine, while the ENT1/2 inhibitor, dipyridamole (10 mg/kg, i.p.), did not affect duration. 5-(3-Bromophenyl)-7-[6-(4-morpholinyl)-3-pyrido[2,3-d]byrimidin-4-amine dihydrochloride (ABT-702), an adenosine kinase inhibitor (5 mg/kg, i.p.), increased the duration of spontaneous adenosine release. The adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) (10 mg/kg, i.p.), also increased the duration in vivo. Similarly, NBTI (10 μmol/L), ABT-702 (100 nmol/L), or EHNA (20 μmol/L) also decreased the clearance rate of exogenously applied adenosine in brain slices. The increases in duration for blocking ENT1, adenosine kinase, or adenosine deaminase individually were similar, about 0.4 sec in vivo; thus, the removal of adenosine on a rapid time scale occurs through three mechanisms that have comparable effects. A cocktail of ABT-702, NBTI, and EHNA significantly increased the duration by 0.7 sec, so the mechanisms are not additive and there may be additional mechanisms clearing adenosine on a rapid time scale. The presence of multiple mechanisms for adenosine clearance on a time scale of seconds demonstrates that adenosine is tightly regulated in the extracellular space. PMID:27022463

  2. Alkaline Phosphatase, Soluble Extracellular Adenine Nucleotides, and Adenosine Production after Infant Cardiopulmonary Bypass

    PubMed Central

    Davidson, Jesse A.; Urban, Tracy; Tong, Suhong; Twite, Mark; Woodruff, Alan

    2016-01-01

    Rationale Decreased alkaline phosphatase activity after infant cardiac surgery is associated with increased post-operative cardiovascular support requirements. In adults undergoing coronary artery bypass grafting, alkaline phosphatase infusion may reduce inflammation. Mechanisms underlying these effects have not been explored but may include decreased conversion of extracellular adenine nucleotides to adenosine. Objectives 1) Evaluate the association between alkaline phosphatase activity and serum conversion of adenosine monophosphate to adenosine after infant cardiac surgery; 2) assess if inhibition/supplementation of serum alkaline phosphatase modulates this conversion. Methods and Research Pre/post-bypass serum samples were obtained from 75 infants <4 months of age. Serum conversion of 13C5-adenosine monophosphate to 13C5-adenosine was assessed with/without selective inhibition of alkaline phosphatase and CD73. Low and high concentration 13C5-adenosine monophosphate (simulating normal/stress concentrations) were used. Effects of alkaline phosphatase supplementation on adenosine monophosphate clearance were also assessed. Changes in serum alkaline phosphatase activity were strongly correlated with changes in 13C5-adenosine production with or without CD73 inhibition (r = 0.83; p<0.0001). Serum with low alkaline phosphatase activity (≤80 U/L) generated significantly less 13C5-adenosine, particularly in the presence of high concentration 13C5-adenosine monophosphate (10.4μmol/L vs 12.9μmol/L; p = 0.0004). Inhibition of alkaline phosphatase led to a marked decrease in 13C5-adenosine production (11.9μmol/L vs 2.7μmol/L; p<0.0001). Supplementation with physiologic dose human tissue non-specific alkaline phosphatase or high dose bovine intestinal alkaline phosphatase doubled 13C5-adenosine monophosphate conversion to 13C5-adenosine (p<0.0001). Conclusions Alkaline phosphatase represents the primary serum ectonucleotidase after infant cardiac surgery and low post

  3. Modulation of adenosine signaling prevents scopolamine-induced cognitive impairment in zebrafish.

    PubMed

    Bortolotto, Josiane Woutheres; Melo, Gabriela Madalena de; Cognato, Giana de Paula; Vianna, Mônica Ryff Moreira; Bonan, Carla Denise

    2015-02-01

    Adenosine, a purine ribonucleoside, exhibits neuromodulatory and neuroprotective effects in the brain and is involved in memory formation and cognitive function. Adenosine signaling is mediated by adenosine receptors (A1, A2A, A2B, and A3); in turn, nucleotide and nucleoside-metabolizing enzymes and adenosine transporters regulate its levels. Scopolamine, a muscarinic cholinergic receptor antagonist, has profound amnesic effects in a variety of learning paradigms and has been used to induce cognitive deficits in animal models. This study investigated the effects of acute exposure to caffeine (a non-selective antagonist of adenosine receptors A1 and A2A), ZM 241385 (adenosine receptor A2A antagonist), DPCPX (adenosine receptor A1 antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in a model of pharmacological cognitive impairment induced by scopolamine in adult zebrafish. Caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered independently via i.p. in zebrafish, followed by exposure to scopolamine dissolved in tank water (200μM). These compounds prevented the scopolamine-induced amnesia without impacting locomotor activity or social interaction. Together, these data support the hypothesis that adenosine signaling may modulate memory processing, suggesting that these compounds present a potential preventive strategy against cognitive impairment. PMID:25490060

  4. Synthesis and biological evaluation of clitocine analogues as adenosine kinase inhibitors.

    PubMed

    Lee, C H; Daanen, J F; Jiang, M; Yu, H; Kohlhaas, K L; Alexander, K; Jarvis, M F; Kowaluk, E L; Bhagwat, S S

    2001-09-17

    Adenosine kinase (AK) is the primary enzyme responsible for adenosine metabolism. Inhibition of AK effectively increases extracellular adenosine concentrations and represents an alternative approach to enhance the beneficial actions of adenosine as compared to direct-acting receptor agonists. Clitocine (3), isolated from the mushroom Clitocybe inversa, has been found to be a weak inhibitor of AK. We have prepared a number of analogues of clitocine in order to improve its potency and demonstrated that 5'-deoxy-5'-amino-clitocine (7) improved AK inhibitory potency by 50-fold. PMID:11549437

  5. Characterization and regulation of adenosine transport in T84 intestinal epithelial cells.

    PubMed

    Mun, E C; Tally, K J; Matthews, J B

    1998-02-01

    Adenosine release from mucosal sources during inflammation and ischemia activates intestinal epithelial Cl- secretion. Previous data suggest that A2b receptor-mediated Cl- secretory responses may be dampened by epithelial cell nucleoside scavenging. The present study utilizes isotopic flux analysis and nucleoside analog binding assays to directly characterize the nucleoside transport system of cultured T84 human intestinal epithelial cells and to explore whether adenosine transport is regulated by secretory agonists, metabolic inhibition, or phorbol ester. Uptake of adenosine across the apical membrane displayed characteristics of simple diffusion. Kinetic analysis of basolateral uptake revealed a Na(+)-independent, nitrobenzylthioinosine (NBTI)-sensitive facilitated-diffusion system with low affinity but high capacity for adenosine. NBTI binding studies indicated a single population of high-affinity binding sites basolaterally. Neither forskolin, 5'-(N-ethylcarboxamido)-adenosine, nor metabolic inhibition significantly altered adenosine transport. However, phorbol 12-myristate 13-acetate significantly reduced both adenosine transport and the number of specific NBTI binding sites, suggesting that transporter number may be decreased through activation of protein kinase C. This basolateral facilitated adenosine transporter may serve a conventional function in nucleoside salvage and a novel function as a regulator of adenosine-dependent Cl- secretory responses and hence diarrheal disorders. PMID:9486178

  6. Adenosine-induced coronary vasospasm following drug-eluting stent implantation

    PubMed Central

    Matsumoto, Naoya; Nagao, Ken; Hirayama, Atsushi; Kasama, Shu

    2014-01-01

    We present the case of coronary vasospasm during adenosine stress in a patient with a prior drug-eluting stent implantation. The patient had a stent implantation in the left anterior descending coronary artery 3 years ago. Recently, he developed a chest pain and underwent adenosine stress myocardial perfusion single photon emission CT (SPECT). During the adenosine stress, he felt severe chest pain and ST elevation on electrocardiogram. An invasive coronary angiography showed no in-stent restenosis. This phenomenon deemed to be adenosine-induced coronary vasospasm after stent implantation. PMID:24518394

  7. Endogenous adenosine is an autacoid feedback inhibitor of chloride transport in the shark rectal gland.

    PubMed Central

    Kelley, G G; Aassar, O S; Forrest, J N

    1991-01-01

    The present studies define the physiologic role of endogenous adenosine in the perfused shark rectal gland, a model epithelia for hormone-stimulated chloride transport. Chloride ion secretion, and venous adenosine and inosine concentrations increased in parallel in response to hormone stimulation. From a basal rate of 157 +/- 26 mu eq/h per g, chloride secretion increased to 836 +/- 96 and 2170 +/- 358 with 1 and 10 microM forskolin, venous adenosine increased from 5.0 +/- 1 to 126 +/- 29 and 896 +/- 181 nM, and inosine increased from 30 +/- 9 to 349 +/- 77 and 1719 +/- 454 nM (all P less than 0.01). Nitrobenzylthioinosine (NBTI), a nucleoside transport inhibitor, completely blocked the release of adenosine and inosine. Inhibition of chloride transport with bumetanide, an inhibitor of the Na+/K+/2Cl- cotransporter, or ouabain, an inhibitor of Na+/K+ ATPase activity, reduced venous adenosine and inosine to basal values. When the interaction of endogenous adenosine with extracellular receptors was prevented by adenosine deaminase, NBTI, or 8-phenyltheophylline, the chloride transport response to secretagogues increased by 1.7-2.3-fold. These studies demonstrate that endogenous adenosine is released in response to hormone-stimulated cellular work and acts at A1 adenosine receptors as a feedback inhibitor of chloride transport. Images PMID:1752953

  8. Molecular vibration-activity relationship in the agonism of adenosine receptors.

    PubMed

    Chee, Hyun Keun; Oh, S June

    2013-12-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands. PMID:24465242

  9. Effects of adenosine and adenosine A2A receptor agonist on motor nerve conduction velocity and nerve blood flow in experimental diabetic neuropathy.

    PubMed

    Kumar, Sokindra; Arun, K H S; Kaul, Chaman L; Sharma, Shyam S

    2005-01-01

    This study examined the effects of chronic administration of adenosine and CGS 21680 hydrochloride (adenosine A(2A) receptor agonist) on motor nerve conduction velocity (MNCV), nerve blood flow (NBF) and histology of sciatic nerve in animal model of diabetic neuropathy. Adenosinergic agents were administered for 2 weeks after 6 weeks of streptozotocin-induced (50 mg/kg i.p.) diabetes in male Sprague-Dawley rats. Significant reduction in sciatic MNCV and NBF were observed after 8 weeks in diabetic animals in comparison with control (non diabetic) rats. Adenosine (10 mg/kg, i.p.) significantly improved sciatic MNCV and NBF in diabetic rats. The protective effect of adenosine on MNCV and NBF was completely reversed by theophylline (50 mg/kg, i.p.), a non-selective adenosine receptor antagonist, suggesting that the adenosine effect was mediated via adenosinergic receptors. CGS 21680 (0.1 mg/kg, i.p.) significantly improved NBF; however, MNCV was not significantly improved in diabetic rats. At a dose of 1 mg/kg, neither MNCV nor NBF was improved by CGS 21680 in diabetic rats. ZM 241385 (adenosine A(2A) receptor antagonist) prevented the effect of CGS 21680 (0.1 mg/kg, i.p.). Histological changes observed in sciatic nerve were partially improved by the adenosinergic agents in diabetic rats. Results of the present study, suggest the potential of adenosinergic agents in the therapy of diabetic neuropathy. PMID:15829161

  10. Adenosine influences myeloid cells to inhibit aeroallergen sensitization.

    PubMed

    Pei, Hong; Linden, Joel

    2016-05-15

    Agonists of adenosine A2A receptors (A2ARs) suppress the activation of most immune cells and reduce acute inflammatory responses. Asthma is characterized by sensitization in response to initial allergen exposure and by airway hyperreactivity in response to allergen rechallenge. We sought to determine if A2AR activation with CGS-21680 (CGS) is more effective when CGS is administered during sensitization or rechallenge. C57BL/6 wild-type mice and Adora2a(f/f)LysMCre(+/-) mice, which lack A2ARs on myeloid cells, were sensitized with intranasal ovalbumin (OVA) and LPS. Airway sensitization was characterized by a rapid increase in numbers of IL-6(+) and IL-12(+) macrophages and dendritic cells in lungs. A2AR activation with CGS (0.1 μg·kg(-1)·min(-1) sc) only during sensitization reduced numbers of IL-6(+) and IL-12(+) myeloid cells in the lungs and reversed the effects of OVA rechallenge to increase airway hyperresponsiveness to methacholine. CGS treatment during sensitization also reduced the expansion of lung T helper (Th1 and Th17) cells and increased expansion of regulatory T cells in response to OVA rechallenge. Most of the effects of CGS administered during sensitization were eliminated by myeloid-selective A2AR deletion. Administration of CGS only during OVA rechallenge failed to reduce airway hyperresponsiveness. We conclude that myeloid cells are key targets of adenosine during sensitization and indirectly modify T cell polarization. The results suggest that a clinically useful strategy might be to use A2AR agonists to inhibit sensitization to new aeroallergens. We speculate that adenosine production by macrophages engulfing bacteria contributes to the curious suppression of sensitization in response to early-life infections. PMID:27016586