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  • Radioenzymatic determination  (2)
  • 3,4-Dihydroxyphenylacetic acid  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Endogenous dopa in rat brain (1981)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 316 (1981), S. 299-303 
    Details
    ISSN: 1432-1912
    Keywords: Endogenous dopa ; Rat brain ; Microwave irradiation ; Radioenzymatic determination ; α-Methyl-p-tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary dopa was isolated from rat brain by cation exchange chromatography and determined by a radioenzymatic method using catechol-O-methyl-transferase and [3H]-S-adenosyl-methionine as cofactor. The product [3H]-methoxytyrosine was purified by cation and anion exchange chromatography. For identification of presumed endogenous dopa isolated from rat brain and rat blood plasma the [3H]-labelled product was purified further by thin-layer chromatography. In the brain of rats killed by decapitation, dopa in a concentration of 7 ng/g was identified. When unstressed rats were killed by focussed microwave irradiation at 2.450 MHz and 8 kW for 1.3 s dopa levels as high as 20 ng/g were measured. The regional distribution of dopa in brain of rats killed by microwaves was similar to the distribution of catecholamines, dopa levels being highest in c. striatum and lowest in cerebellum. Inhibition of tyrosine hydroxylase with α-methyl-p-tyrosine methylester HCl, 250 mg/kg i.p. 90 min before death did not change the brain dopa levels in rats killed by decapitation or in rats killed by microwaves. Compounds, such as haloperidol, chlorpromazine, apomorphine and pentobarbital which are known to increase or decrease catecholamine synthesis did not change the basal level of dopa. The data indicate that in rat brain, the main portion of dopa is associated with catecholamine-containing nerve terminals and that this portion is present in a pool which is only slowly metabolized. A second very small pool of dopa must exist, which is serving as precursor pool for catecholamines and which is turned over at a higher rate. It can be concluded that the basal dopa level cannot be used as an indicator of catecholamine synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501361
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Conjoint radioenzymatic measurement of catecholamines, their catechol metabolites and DOPA in biological samples (1981)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 318 (1981), S. 19-28 
    Details
    ISSN: 1432-1912
    Keywords: 3,4-Dihydroxyphenylacetic acid ; 3,4-Dihydroxymandelic acid ; 3,4-Dihydroxyphenylethanol ; 3,4-Dihydroxyphenylglycol ; Radioenzymatic determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An assay is described for the simultaneous determination of dopamine, noradrenaline, adrenaline, dopa, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenyl-ethanol, 3,4-dihydroxymandelic acid and 3,4-dihydroxy-phenylglycol, capable of detecting amounts in the femtomol range. The assay is based on the O-methylation of the catechol moiety utilizing S-[3H-methyl]-adenosyl-l-methionine and a partially purified catechol-O-methyl transferase to form the various O-[3H-methyl]-catechol derivatives. The O-[3H-methyl]-catechol derivatives are purified by thin layer chromatography, solvent partitions and/or ion exchange chromatography. The assay was successfully applied to biological sample. It was possible for the first time, to detect free 3,4-dihydroxy-phenylglycol, free 3,4-dihydroxyphenylethanol and 3,4-dihydroxymandelic acid in a small volume (25μl) of blood plasma of man, rat, dog and rabbit. The conjoint measurement of catecholamines and their catechol metabolites in minute amounts of biological samples may contribute to a more detailed understanding of catecholamine metabolism in the peripheral and central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503307
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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