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  • 1
    ISSN: 1432-2013
    Keywords: Lacrimal gland ; Cl− activity ; Acetylcholine ; Cl− permeability ; Ca2+ ionophore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using double-barreled Cl−-sensitive microelectrodes, intracellular Cl− activity (A Cl i ) in the mouse lacrimal acinar cells in vitro was determined in both resting and secretory phases. In the resting stateA Cl i was 31 mmol/l which was 1.4 times higher than that predicted for the passive distribution according to the membrane potential (V m) of −41 mV. Addition of acetylcholine (ACh, 1μM) hyperpolarizedV m to −63 mV and decreasedA Cl i to 20 mmol/l which was still twice the equilibrium activity. A-23178 produced similar changes inV m andA Cl i to those induced by ACh. It was concluded that Cl− was actively accumulated in the acinar cells and, in the secretory phase, Cl− efflux was enhanced by the increased driving force and Ca2+-mediated increase in the Cl− permeability across the cell membrane.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Na+/H+ exchange ; Intracellular pH regulation ; Salivary gland ; Protein kinase C ; Intracellular Ca2+ ; Acetylcholine ; Ionomycin ; Phorbol esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanism of regulation of intracellular pH (pHi) in dispersed acini from the rat mandibular salivary gland has been studied with a microfluorimetric imaging method and the pH probe 2′,7′-bis(2-carboxyethyl)-5(and −6)-carboxyfluorescein. The pHi in the TRIS/HEPES-buffered standard solution was 7.29±0.01. Addition of 1 μmol/l acetylcholine (ACh) or ionomycin caused a sustained increase in the pHi. These agents decreased pHi in the absence of external Na+ or in the presence of amiloride. The rate of pHi recovery from an acid load after NH 4 + prepulse was a linear function of pHi and increased as pHi became more acidic. Addition of ACh shifted the relationship towards a more alkaline pHi range. The increase in pHi induced by ACh or ionomycin was not inhibited by the protein kinase C inhibitors staurosporine (10 nM) and 1-(5-isoquinolinesulfonyl)-1-methylpiperazine (50 μmol/l). Addition of 0.1–1 μmol/l phorbol 12-myristate 13-acetate (TPA) had little effect on pHi within 10 min; however, exposure to TPA for 120 min resulted in a significant rise in pHi. In Ca2+-free solution with 50 μmol/l 8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate, the ACh-induced rise in both pHi and cytosolic Ca2+ concentration was suppressed. ACh and ionomycin caused an increment of amiloride-sensitive acid output into the extracellular fluid, while 20 μmol/l 1-oleoyl-2-acetylglycerol had little effect on it. It was concluded that (a) stimulation with ACh activated the Na+/H+ antiport in the plasma membrane, (b) ACh also stimulated the intracellular acid production but acid extrusion by the Na+/H+ antiport prevented the cell from intracellular acidification, and (c) the major route of signal transduction for the ACh-induced activation of the Na+/H+ antiport was independent of protein kinase C but was dependent on the rise in cytosolic Ca2+ concentration. The implication of the cytosolic acidification and cell volume change in pHi regulation is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 31 (1980), S. 763-768 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Geschwindigkeit der Wasserstoffaufnahme von Eisen: Einfluß von Halidionen, Schwefelwasserstoff und HexynolBestimmt wird der Einfluß von Chlor-, Brom- und Iodionen auf die Geschwindigkeit der Wasserstoffentwicklung an und die Wasserstoffpenetration in Eisen in Schwefelsäure (auch mit Schwefelwasserstoffzusatz). Die Ergebnisse werden verglichen mit denen, die durch Hexynol als Inhibitor erhalten wurden. Bei Zusatz von Halidionen nehmen die Wasserstoffentwicklung sowie die Wasserstoffpenetration und auch der Korrosionsstrom in der Reihenfolge Cl-〉 Br-〉 I- ab. Schwefelwasserstoff katalysiert sowohl die Wasserstoffentwicklung als auch die Wasserstoffpenetration; dabei scheint die katalytische Wirksamkeit im Falle der Penetration von der Schwefelwasserstoffkonzentration abhängig zu sein, im Falle der Wasserstoffentwicklung hingegen nicht. Der Anteil des entstehenden Wasserstoffs, der vom Eisen aufgenommen wird, ist größer, wenn ständig neue Eisenoberfläche entsteht als bei kathodischer Polarisation. Der Zusatz des Acetylenalkohols Hexynol inhibiert sowohl die Wasserstoffentwicklung als auch die Wasserstoffpenetration in der Schwefelsäure mit Schwefelwasserstoff- und Halidzusätzen.
    Notes: The effect of the halides (Cl-, Br- and I-) on the rates of the hydrogen evolution reaction (h. E. R.) and hydrogen penetration (h. P.) of iron in H2SO4 is determined. The H. E. R. and H. P. of Fe in these same electrolytes with the addition of H2S are also studied. The inhibition of corrosion and h. p. in the H2S environment by hexynol are compared. With halide addition her., icorr and h. p. decreased in the following order, Cl-〉 Br-〉 I-. H2S catalyzed both the h. e. r. and h. p. The catalytic activity does not appear dependent on the H2S concentration for the H. E. R. but does for H. P. The fraction of hydrogen generated which is absorbed by Fe is greater during corrosion when a new surface is formed continuously than during cathodic polarization. The addition of the acetylenic alcohol, hexynol, in H2SO4 containing H2S and halides inhibited the h. e. r. corrosion and h. p.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 436-440 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energy difference (ΔE) between the two types of rotamers of β-methoxyethylmercuric chloride has been satisfactorily determined by only assuming the ratio of vicinal trans and gauche H—H coupling constants. The validity of the result was confirmed by the large temperature dependence of the vicinal Hg—H couplings in various solvents. Moreover, it has become possible to determine small values of ΔE in nonpolar solvents. Two ΔE values of β-methoxypropylmercuric chloride in various solvents were determined on the basis of the substituent electronegativity effect on the H—H couplings and their validity was supported by the large temperature dependence of the vicinal Hg—H couplings. With regard to erythro- and threo-(α-methyl-β-methoxy)propylmercuric chlorides, both the H—H and Hg—H couplings were used to estimate the values of ΔE among the rotamers. Throughout the mercury compounds, it was ascertained that the more polar the solvent, the greater the preference for the conformation with the trans disposed HgCl and OCH3 groups. Excellent agreement between the observed facts and the calculations by extended Hückel theory were shown with regard to the relative magnitude of the rotamer polarity and the conformational energy difference of these mercury compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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