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M HCl (m + hcl)
Terms modified by M HCl Selected AbstractsElectroanalytical Determination of Cadmium(II) and Lead(II) Using an Antimony Nanoparticle Modified Boron-Doped Diamond ElectrodeELECTROANALYSIS, Issue 10 2009Kathryn Abstract We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by linear sweep anodic stripping voltammetry (LSASV) using an antimony nanoparticle modified boron doped diamond (Sb-BDD) electrode. Sb deposition was performed in situ with the analytes, from a solution of 1,mg L,1 SbCl3 in 0.1,M HCl (pH,1). Pb2+ inhibited the detection of Cd2+ during simultaneous additions at the bare BDD electrode, whereas in the presence of antimony, both peaks were readily discernable and quantifiable over the linear range 50,500,,g L,1. [source] Enhancement of Anodic Response for DMSO at Ruthenium Oxide Film Electrodes as a Result of Doping with Iron(III)ELECTROANALYSIS, Issue 2 2003Brett Abstract The oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2) is representative of numerous anodic oxygen-transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO2 -film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO2 films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO2 films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)-doped RuO2 -film electrode prepared using a deposition solution of 50,mM RuCl3 and 10,mM FeCl3 in a 1,:,1 mixture of isopropanol and 12,M HCl at an annealing temperature of 450,°C. The Levich plot (i vs. ,1/2) and Koutecky-Levich plot (1/i vs. 1/,1/2) of amperometric data for the oxidation of DMSO at an Fe(III)-doped RuO2 -film electrode configured as a rotated disk are consistent with an anodic response controlled by mass-transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)-doped RuO2 -film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100-,L injections of the three compounds are ca. 3.2×10,4,mM, i.e., ca. 32,pmol. [source] Supramolecular Chemistry Based on [W3S4(H2O)6Cl3]+ , A Versatile Building BlockEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2004Maxim N. Sokolov Abstract The cluster [W3S4(H2O)6Cl3]+ (which is present in solutions of [W3S4(H2O)9]4+ in 1,4 M HCl) reacts with the macrocyclic cavitand cucurbituril (C36H36N24O12) to form supramolecular adducts of 2:1 cluster/cucurbituril stoichiometry, where two portals of cucurbituril (which contains a water molecule in its cavity) are closed by two cluster cations. These aggregates are bound together in the solid by complementary hydrogen bonds between coordinated Cl, and the cations H9O4+ to give chains. Thus, a supramolecular architecture is achieved from three different but complementary building blocks. The packing of the chains affords a honeycomb structure (hexagonal symmetry) with channels (about 5.2 Ĺ in diameter). The overall stoichiometry is (H9O4){[W3S4(H2O)6Cl3]2(C36H36N24O12)}Cl3·16.15H2O (1). [W3S4(H2O)6Cl3]+ reacts with SbCl3 in 6 M HCl to give cuboidal [W3(SbCl3)S4(H2O)6Cl3]+, which forms with the macrocyclic cavitand cucurbituril a 2:1 cluster/cucurbituril adduct , a discrete supramolecule consisting of five independent molecular units. In the solid it crystallizes as a salt of very rare anion [SbCl6]3, with the stoichiometry {[W3(SbCl3)S4(H2O)6Cl3]2(C36H36N24O12)}(SbCl6)2/3·12H2O (2). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Asymmetric Synthesis of (1,3-Butadien-2-yl)methanols from Aldehydes via [1-(Silylmethyl)allenyl]methanolsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2010María Durán-Galván Abstract [1-(Silylmethyl)allenyl]methanols 2 were efficiently synthesized from aldehydes and (4-bromobut-2-ynyl)trimethylsilane in the presence of a catalytic amount of CrCl2 and tridentate carbazole ligands. The desired compounds were obtained with good yields (43,88,%) and enantioselectivities (55,78,% ee). Alcohols 2 may be treated with TBAF or 2 M HCl in the case of aliphatic substrates, to provide (1,3-butadien-2-yl)methanols 3 in 43,81,% yields. This method allows the synthesis of dienes 3 with no regioselectivity problems, and it tolerates a large number of functionalities. [source] H2xMnxSn3-xS6 (x,=,0.11,0.25): A Novel Reusable Sorbent for Highly Specific Mercury Capture Under Extreme pH ConditionsADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Manolis J. Manos Abstract The H2xMnxSn3-xS6 (x,=,0.11,0.25) is a new solid acid with a layered hydrogen metal sulfide (LHMS). It derives from K2xMnxSn3,xS6 (x,=,0.5,0.95) (KMS-1) upon treating it with highly acidic solutions. We demonstrate that LHMS-1 has enormous affinity for the very soft metal ions such as Hg2+ and Ag+ which occurs via a rapid ion exchange process. The tremendous affinity of LHMS-1 for Hg2+ is reflected in very high distribution coefficient KdHg values (>106,mL g,1). The large affinity and selectivity of LHMS-1 for Hg2+ persists in a very wide pH range (from less than zero to nine) and even in the presence of highly concentrated HCl and HNO3 acids. LHMS-1 is significantly more selective for Hg2+ and Ag+ than for the less soft cations Pb2+ and Cd2+. The Hg2+ ions are immobilized in octahedral sites between the sulfide layers of the materials via Hg,S bonds as suggested by pair distribution function (PDF) analysis. LHMS-1 could decrease trace concentrations of Hg2+ (e.g. <100,ppb) to well below the acceptable limits for the drinking water in less than two min. Hg-laden LHMS-1 shows a remarkable hydrothermal stability and resistance in 6,M HCl solutions. LHMS-1 could be regenerated by treating Hg-loaded samples with 12,M HCl and re-used without loss of its initial exchange capacity. [source] Effects of mixed aqueous-organic solvents on the rate of intramolecular carboxylic group-catalyzed cleavage of N -(4,-methoxyphenyl)phthalamic acidINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2004Sim Yoke Leng Kinetic study on the cleavage of N -(4,-methoxyphenyl)phthalamic acid (NMPPAH) in mixed H2O-CH3CN and H2O-1,4-dioxan solvents containing 0.05 M HCl reveals the formation of phthalic anhydride (PAn)/phthalic acid (PA) as the sole or major product. Pseudo first-order rate constants (k1) for the conversion of NMPPAH to PAn decrease nonlinearly from 60.4 × 10,5 to 2.64 × 10,5 s,1 with the increase in the contents of 1,4-dioxan from 10 to 80% v/v in mixed aqueous solvents. The rate of cleavage of NMPPAH in mixed H2O-CH3CN solvents at ,50% v/v CH3CN follows an irreversible consecutive reaction path: NMPPAH PA. The values of k1 are larger in H2O-CH3CN than in H2O-1,4-dioxan solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 316,325, 2004 [source] Soluble Microcapsules Assembled Stepwise from Weak Polyelectrolytes Using Acid-Decomposable Cores,ADVANCED MATERIALS, Issue 11 2003C.-Y. Gao Decomposable microcapsules with tunable permeability, loading, and release properties,with potential applications as chemical reservoirs and for controlled drug release,have been fabricated by assembly of weak polyelectrolytes on melamine formaldehyde templates followed by removal of the cores at low pH by precise control of the time of acid treatment. The Figure shows capsules before (left) and after (right) treatment with 0.1 M HCl. [source] THE FREE RADICAL-SCAVENGING PROPERTY OF CHONDROITIN SULFATE FROM PIG LARYNGEAL CARTILAGE IN VITROJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2007SHUANG-LI XIONG ABSTRACT This study compared the free radical-scavenging properties of chondroitin sulfate (ChS) from pig laryngeal cartilage and its reduced or sulfonated derivatives. The binding behavior between Cu2+ and ChS and its derivatives, and the interaction between superoxide radical and ChS were studied by fluorescence quenching, equilibrium dialysis, infrared spectra and thermal analysis. Purified ChS inhibited the generation of hydroxyl radical and scavenged superoxide radical in a concentration-dependent manner. Reduced ChS did not scavenge hydroxyl radical and superoxide radical. Sulfonated ChS had no hydroxyl radical scavenging activity but scavenged superoxide radical as strongly as purified ChS. ChS showed strong binding activity with Cu2+ in deionized water but not in 0.01-M HCl. Both reduced ChS and sulfonated ChS did not exhibit such chelating behavior. The structural basis of hydroxyl radical inhibiting of ChS was attributed to a complex of the Cu2+ with the carboxyl group of glucuronic acid residue. The reaction of superoxide radical with the sulfate ester and the carboxyl group may be the basis of superoxide radical scavenging activity of ChS. [source] Properties of Arrowroot Starch Treated with Aqueous HCl at Ambient TemperatureJOURNAL OF FOOD SCIENCE, Issue 1 2002J.K. John Arrowroot starch was acid-treated using 2.2 M HCl at 29 to 30° C for durations of 0 to 72 h, and properties of the control and modified samples were compared. Increasing length of acid treatment produced a progressive decline in amylose blue value, intrinsic viscosity, and swelling power, as well as an increase in free sugars and solubility. Differential scanning calorimetry (DSC) studies highlighted changes effected by acid-treatment in the gelatinization behavior of the starch samples. Gel permeation chromatography (GPC) studies on 32- and 72-h acid-treated samples indicated a greater proportion of dextrins with a higher percentage of reducing sugars, compared to the control. While X-ray diffraction data suggested minor changes in the crystal phase impacted by acid-treatment, in vitro digestibility of both control and acid-treated samples did not show any appreciable change in overall patterns. [source] Complete sequences of small acid-soluble proteins from Bacillus globigiiJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2004Jeffrey R. Whiteaker Abstract Three abundant small acid-soluble proteins (SASPs) from spores of Bacillus globigii were sequenced using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with post-source decay and nanoelectrospray collision-induced dissociation tandem mass spectrometry. The proteins were extracted from spores with 1 M HCl. Scanning electron micrographs of spores before and after acid extraction show that the spores retain their overall structure but have a shriveled texture following the acid treatment. Extracted SASPs were purified by high-performance liquid chromatography and molecular masses of the SASPs were identified at 7068 (SASP-1), 7332 (SASP-2), and 8889 (,-SASP). De novo peptide sequencing was used to determine the protein sequences. The correct ordering of peptide sequences was aided by mapping overlapping enzymatic digests and by comparison with homologous SASPs from Bacillus stearothermophilus. B. globigii is used in many field tests as a surrogate for B. anthracis. Thus complete SASP sequences from B. globigii will facilitate the development of methods for rapid identification of bacteria based on mass spectrometry and the examination of taxonomic relationships between Bacillus species. Copyright © 2004 John Wiley & Sons, Ltd. [source] Specific acid catalysis and Lewis acid catalysis of Diels,Alder reactions in aqueous mediaJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 3 2004Egid B. Mubofu Abstract A comparative study of specific acid catalysis and Lewis acid catalysis of Diels,Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas hydrochloric acid was employed for specific acid catalysis. At equimolar amounts of copper(II) nitrate and hydrochloric acid (0.01,M, for example) and under the same reaction conditions, the reaction rate for 1a with 2 is about 40 times faster with copper catalysis than with specific acid catalysis. Moreover, at 32°C and 0.01,M HCl, the reaction of 1b with 2 is about 21 times faster than the same uncatalyzed reaction in pure water under the same reaction conditions. The inverse solvent kinetic isotope effect shows that these Diels,Alder reactions undergo specific acid catalysis. Copyright © 2004 John Wiley & Sons, Ltd. [source] Influence of Tithonia diversifolia and triple superphosphate on dissolution and effectiveness of phosphate rock in acidic soilJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2006Isaac Savini Abstract An incubation and a pot experiment were conducted to evaluate the dissolution and agronomic effectiveness of a less reactive phosphate rock, Busumbu soft ore (BPR), in an Oxisol in Kenya. Resin (anion and anion + cation)-extractable P and sequentially extracted P with 0.5 M NaHCO3, 0.1 M NaOH, and 1 M HCl were analyzed. Dissolution was determined from the increase in anion resin (AER),, NaHCO3 -, and NaOH-extractable P in soil amended with PR compared with the control soil. Where P was applied, resin P significantly increased above the no-P treatment. Busumbu-PR solubility was low and did not increase significantly in 16 weeks. Anion + cation (ACER)-extractable P was generally greater than AER-P. The difference was greater for PR than for triple superphosphate (TSP). The ACER extraction may be a better estimate of plant P availability, particularly when poorly soluble P sources are used. Addition of P fertilizers alone or in combination with Tithonia diversifolia (TSP, BPR, TSP + Tithonia, and BPR + Tithonia) increased the concentration of labile inorganic P pools (NaHCO3 - and NaOH-Pi). Cumulative evolved CO2 was significantly correlated with cumulative N mineralized from Tithonia (r, 0.51, p < 0.05). Decrease in pH caused NH -N accumulation while NO -N remained low where Tithonia was incorporated at all sampling times. However, when pH was increased, NH -N declined with a corresponding rise in NO -N. Tithonia significantly depressed soil exchangeable acidity relative to control with time. A significant increase (p < 0.05) was observed for P uptake but not dry-mass production in maize where BPR was applied. The variations in yield and P uptake due to source and rates of application were statistically significant. At any given P rate, highest yields were obtained with Tithonia alone. Combination of Busumbu PR with TSP or Tithonia did not enhance the effectiveness of the PR. The poor dissolution and plant P uptake of BPR may be related to the high Fe content in the PR material. [source] Chromatographic separation of cytidine triphosphate from fermentation broth of yeast using anion-exchange cryogelJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2008Lianghua Wang Abstract A novel separation method was developed to isolate directly cytidine triphosphate (CTP) from fermentation broth of yeast using anion-exchange supermacroporous cryogel. The anion-exchange cryogel with tertiary amine groups was prepared by graft polymerization. The breakthrough characteristics and elution performance of pure CTP in the cryogel bed were investigated experimentally and the CTP binding capacity was determined. Then the separation experiments of CTP from crude fermentation broth of yeast using the cryogel column were carried out using deionized water and 0.01 M HCl as washing buffer, respectively. The chromatographic behavior was monitored and analyzed. The purity and concentration of the obtained CTP in these processes were determined quantitatively by HPLC. The maximal purity of CTP obtained at the condition of 0.01 M HCl as washing buffer and 0.5 M NaCl in 0.01 M HCl as elution buffer reached 93%. [source] Functionalized HMS mesoporous silica as solid phase extractant for Pb(II) prior to its determination by flame atomic absorption spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2007Damián Pérez-Quintanilla Abstract In this work, a mesoporous silica has been chemically modified with 5-mercapto-1-methyl-1-H-tetrazol using the homogeneous route (MTTZ-HMS). This synthetic route involved the reaction of 5-mercapto-1-methyl-1-H-tetrazol with 3-chloropropyltriethoxysilane, prior to immobilization on the support. The resulting material has been characterized and employed as solid phase extractant for Pb(II). The effect of several variables (stirring time, pH, temperature, metal concentration, presence of other metals) has been studied using batch and column techniques. In batch experiments, 15 min stirring time, 55°C and pH 8 were the optimal conditions for Pb(II) adsorption. In column experiments, sorption was quantitative for 1000 mL of 2.41×10,4 mM of Pb(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water was used for the preconcentration and determination of Pb(II) by flame atomic absorption spectrometry, and a 100% recovery was obtained. The LOD and LOQ values of the proposed method were found to be 3.52×10,3 and 4.20×10,3 mM, respectively. The RSD for three preconcentration experiments was found to be ,2%. The linear working range for measurements was between 2×10,3 and 0.14 mM (y = 0.0136x + 0.0007, R2 = 0.9999). [source] Preparation and properties investigation of PMMA/silica composites derived from silicic acidPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2009H. P. Fu Abstract Hybrid materials based on silicic acid and polymethyl methacrylate (PMMA) were prepared by in situ bulk polymerization of a silicic acid sol and MMA mixture. Silicic acid sol was obtained by tetrahydrofuran (THF) extraction of silicic acid from water. Silicic acid was prepared by hydrolysis and condensation of sodium silicate in the presence of 3.6,M HCl. As a comparative study, PMMA composites filled by silica particles, which were derived from calcining the silicic acid gel, were prepared by a comparable in situ polymerization. Each set of PMMA/silica composites was subjected to thermal and mechanical studies. Residual THF in PMMA/silicic acid composites impacted the properties of the polymer composites. With increase in silica content, the PMMA composites filled with silica particles showed improved thermal and mechanical properties, whereas a decrease in thermal stability and mechanical strength was found for PMMA composites filled with silicic acid dissolved in THF. With a better compatibility with polymer matrix, silicic acid sol shows better reinforcement than silica particles in PMMA films prepared via blending of the corresponding THF solutions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Preparation, morphology and electrical conductivity of polyaniline/polyoxyalkylene,montmorillonite exfoliated nanocompositesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008N. Salahuddin Abstract Polyaniline (PANI)/organoclay exfoliated nanocomposites containing different organoclay contents (14,50,wt%) were prepared. PANI emeraldine base (EB) and oligomeric PANI (o-PANI) were intercalated into montmorillonite (MMT) modified by four types of polyoxyalkylene diamine or triamine (organoclay) using N-methyl pyrolidinone (NMP) as a solvent in the presence of 0.1,M HCl. o-PANI and EB have been synthesized by oxidative polymerization of aniline using ammonium peroxydisulfate (APS). Infrared absorption spectra (IR) confirm the electrostatic interaction between negatively charged surface of MMT and positively charged sites in PANI. X-ray diffraction (XRD) studies disclosed that the d001 spacing between interlamellar surface disappeared at low content of the organoclay. The morphology of these materials was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrical conductivities of the PANI-organoclay and o-PANI-organoclay nanocomposites were 1.5,×,10,3,2,×,10,4 and 9.5,×,10,7,1.8,×,10,9,S/cm, respectively depending on the ratio of PANI. Copyright © 2007 John Wiley & Sons, Ltd. [source] Characterisation of oxazepam degradation products by high-performance liquid chromatography/electrospray ionisation mass spectrometry and electrospray ionisation quadrupole time-of-flight tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010Thomas J. P. Smyth Oxazepam has been subjected to controlled degradation at 100°C for 3,h in 0.5,M HCl and 0.5,M NaOH. Following neutralisation of the degradation mixture and removal of salts by solid-phase extraction (SPE), isocratic high-performance liquid chromatography/mass spectrometry (HPLC/MS) using water/methanol (25:75,v/v) as the mobile phase was carried out using a flow diverter to collect fractions prior to their characterisation by electrospray ionisation multi-stage mass spectrometry (ESI-MSn) and proposal of the corresponding fragmentation patterns. The elemental compositions of the degradation products and their MS fragments were evaluated using electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) which was then used to support the proposed fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] Polystyrene-supported N -sulfonylated amino alcohols and their applications to titanium(IV) complexes catalyzed enantioselective diethylzinc additions to aldehydesCHIRALITY, Issue 1 2007Xin-Ping Hui Abstract Crosslinked polystyrene-supported resins 4, 7a, and 7b containing N -sulfonylated ,-amino alcohol in 98, 20, and 40% loadings are prepared. Asymmetric diethylzinc additions to benzaldehyde employing titanium complexes of 10 mol % resins 4, 7a, or 7b are examined and the best performed 7a/Ti(O- i -Pr)4 catalytic system applies to various aldehydes to afford desired secondary alcohols in excellent enantioselectivities up to 95% ee. The resin 7a is reused five times, giving the product with enantioselectivities ,86% ee and an 81% ee is obtained when the resin is used the sixth time. The used resin 7a is refreshed with 1 M HCl and the asymmetric reaction employing the regenerated resin 7a gives the product in 88% ee. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source] Amino acid 15N in long-term bare fallow soils: influence of annual N fertilizer and manure applicationsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2008R. Bol Summary Long-term dynamics of amino acids (AAs), from a bare fallow soil experiment (established in 1928 at INRA-Versailles, France), were examined in unamended control (Con) plots and plots treated with ammonium sulphate (Amsul), ammonium nitrate (Amnit), sodium nitrate (Nanit) or with animal manure (Man). Topsoil (0,25 cm) from 1929, 1963 and 1997 was analysed for C, N and 15N content and distribution of 18 amino acids recovered after acid hydrolysis with 6 m HCl. With time, soil N, C and AA content were reduced in Con, Amsul, Amnit and Nanit, but increased in Man. However, the absolute N loss was 3,11 times larger in Man than Nanit, Amsul, Amnit and Con, due to the much higher N annual inputs applied to Man. From 1929 to 1997 in Con, Amsul, Amnit and Nanit the whole soil and non-hydrolysable-N pool ,15N increased associated with the loss of N (indicative of Rayleigh 15N/14N fractionation). No ,15N change from 1929 to 1997 was found in the hydrolysable AA-N (HAN) pool. Fertilizer N inputs aided stabilization of soil AA-N, as AA half-life in the mineral N fertilizer treatments increased from 34 years in 1963 to 50 years in 1997. The ,15N values of alanine and leucine reflected both source input and 15N/14N fractionation effects in soils. The ,15N increase of ornithine (,6,) was similar to the whole soil. The ,15N change of phenylalanine in Con (decrease of 7,) was related to its proportional loss since 1929, whereas for Amsul, Amnit, Nanit and Man it was associated with isotope effects caused by the fertilizer inputs. However, the soil ,15N value of most individual amino acids (IAAs) did not significantly change over nearly 70 years, even with mineral or organic N inputs. We conclude for these bare fallow systems that: (i) ,15N changes in the whole soil and non-hydrolysable AA pool were solely driven by microbial processes and not by the nature of fertilizer inputs, and (ii) without plant inputs, the ,15N of the HAN pool and (most) IAAs may reflect the influence of plant,soil interactions from the previous (arable cropping) rather than present (fallow) land use on these soil ,15N values. [source] The roles of prostaglandin E receptor subtypes in the cytoprotective action of prostaglandin E2 in rat stomachALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2000H. Araki Summary Aim: To investigate the EP receptor subtype involved in the gastroprotective action of prostaglandin (PG) E2 using various EP receptor agonists in rats, and using knockout mice lacking EP1 or EP3 receptors. Methods: Male SD rats and C57BL/6 mice were used after an 18-h fast. Gastric lesions were induced by oral administration of HCl/ethanol (150 m m HCl in 60% ethanol). Rats were given various EP agonists i.v. 10 min before HCl/ethanol: PGE2, sulprostone (EP1/EP3 agonist), butaprost (EP2 agonist), 17-phenyl-,-trinorPGE2 (17-phenylPGE2: EP1 agonist), ONO-NT012 (EP3 agonist) and 11-deoxyPGE1 (EP3/EP4 agonist). In a separate study, the effect of PGE2 on HCl/ethanol lesions was examined in EP1 - and EP3 -receptor knockout mice. Results: Gastric lesions induced by HCl/ethanol were dose dependently prevented by PGE2; this effect was mimicked by sulprostone and 17-phenylPGE2 and was significantly antagonized by ONO-AE-829, an EP1 antagonist. Neither butaprost, ONO-NT012 nor 11-deoxyPGE1 exhibited any protective activity against HCl/ethanol-induced gastric lesions. PGE2 caused an inhibition of gastric motility as well as an increase of mucosal blood flow and mucus secretion, the effects being mimicked by prostanoids activating EP1 receptors, EP2/EP3/EP4 receptors and EP4 receptors, respectively. On the other hand, although HCl/ethanol caused similar damage in both wild-type mice and knockout mice lacking EP1 or EP3 receptors, the cytoprotective action of PGE2 observed in wild-type and EP3 -receptor knockout mice totally disappeared in mice lacking EP1 receptors. Conclusion: The gastric cytoprotective action of PGE2 is mediated by activation of EP1 receptors. This effect may be functionally associated with inhibition of gastric motility but not with increased mucosal blood flow or mucus secretion. [source] | |||||||||||||||||||||||||