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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 294 (1976), S. 61-68 
    ISSN: 1432-1912
    Keywords: p-Nitrophenyl diazonium fluoroborate ; Cholinergic neurons ; Acetylcholine receptor ; Acetylcholinesterase ; Affinity labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrophysiological experiments were done to investigate the effect of p-nitrophenyl diazonium fluoroborate (p-NPD) on motor endplates of the frog's m. cutaneus pectoris. The compound has no direct depolarizing effect on the postsynaptic membrane and stabilizes it irreversibly when added to the bath. Longtime iontophoretical applications of p-NPD produce a biphasic effect: initially a potentiation of the depolarizations due to acetylcholine (ACh) (both iontophoretically applied and presynaptically liberated), and subsequently an inhibition of the response to ACh. When the acetylcholinesterase (AChE) is inactivated previously, only the inhibiting effect of the compound is demonstrable. The association constant of p-NPD to purified AChE and to membrane fragments of electroplax was determined by biochemical methods. The compound's affinity to the AChE was found to be about 20 times greater than to the acetylcholine receptor (AChR). Iontophoretical application of p-NPD to cholinergic neurons in the hippocampal cortex of the cat also produced the characteristic biphasic effect on ACh-induced activity of these investigated neurons. The results suggest that the biphasic effect depends on the capacity of p-NPD to combine with both the AChE and the AChR. The AChE is first inhibited with low concentrations thereby potentiating the ACh response. At higher concentrations the AChR's are progressively inhibited too, thereby diminishing the excitability of the postsynaptic membrane up to a complete block.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 40 (1957), S. 888-906 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird die Synthese von substituierten β-Amino-tetrahydrofuranen und deren quaternären Salzen beschrieben. Als Ausgangsmaterialien dienten entweder γ-Lactone oder α-Acetylenketone oder Furan-3-carbonsäure. Von den [2-(α-Hydroxyäthy1)-tetrahydro-furyl-(4)]-trimethylammonium-Verbindungen wurden zwei Racemate isoliert, die sich als verschieden von Muscarin erwiesen. Katalytische Oxydation rnit Platin-Sauerstoff ergab beim Muscarin ein Keton (Ketomuscarin), dessen IR.-Spektrum auf ein Fünfring-Keton schliessen lässt. Aus dem Verhalten des Ketomuscarins gegenüber Alkali ist zu schliessen, dass die Trimethylammoniumgruppe nicht in α- oder β-Stellung zur Carbonylgruppe stehen kann, und dass dem Muscarin folglich Formel III zuzuweisen ist.Die pharmakologische Prüfung der synthetischen Produkte an Froschorganen und Katzen auf muscarinische, nikotinische und curareartige Wirkungen ergab eine gegenüber Muscarin geringere muscarin-, hingegen verstärkte nikotin- und curareartige Wirksamkeit.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Furan-4-carbonester lassen sich mit Dimethylformamid und Phosphoroxychlorid in Stellung 2 formylieren. Die reduktive Aminierung der Aldehydgruppe gelingt katalytisch mittels LINDLAR-Katalysator ohne überwiegenden EMDE-Abbau.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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