Document Detail


Errors introduced by a tritium label in position 8 of catecholamines.
MedLine Citation:
PMID:  2419773     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The neuronal and extraneuronal disposition of 3H-7,8- and 3H-7-labelled (-)-noradrenaline and dopamine was compared in in vitro studies. In agreement with earlier studies, the present results show that the presence of a tritium label in position 8 (i.e., on the alpha-carbon) has two consequences: a) the rate of deamination declines and b) part of the deamination results in the formation of an unlabelled aldehyde plus tritium water; tritium water is recovered from the OMDA-fraction of the column chromatographic procedure of Graefe et al. (1973). Whenever the deamination of a 3H-catecholamine is reduced (by tritium in position 8), the intraneuronal 3H-catecholamine concentration is increased. This increase, in turn, partly masks the decline in neuronal deamination (rat vas deferens). Irrespective of whether one determines the spontaneous efflux, the release of 3H-noradrenaline by nerve stimulation or the release of 3H-(-)-noradrenaline by the reserpine-like compound Ro 4-1284, the presence of tritium in position 8 distorts the results (experiments with rat vasa deferentia and/or rabbit aorta). In the extraneuronal system of the rat heart, two intracellular enzymes inactivate 3H-(-)-noradrenaline and 3H-dopamine: catechol-O-methyl transferase (COMT) and monoamine oxidase (MAO). Any hindrance of deamination (by tritium in position 8, COMT intact) leads to a shift of the metabolism of the 3H-catecholamines from the exclusively deaminated to the exclusively O-methylated metabolites. No differences between 3H-7,8- and 3H-7-labelled catecholamines were found after inhibition of MAO and COMT (extraneuronal accumulation and rate constant for efflux from the extraneuronal compartment III of the rat heart).(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
M Grohmann; M Henseling; L Cassis; U Trendelenburg
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Naunyn-Schmiedeberg's archives of pharmacology     Volume:  332     ISSN:  0028-1298     ISO Abbreviation:  Naunyn Schmiedebergs Arch. Pharmacol.     Publication Date:  1986 Jan 
Date Detail:
Created Date:  1986-04-22     Completed Date:  1986-04-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0326264     Medline TA:  Naunyn Schmiedebergs Arch Pharmacol     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  34-42     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
2H-Benzo(a)quinolizin-2-ol, 2-Ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy- / pharmacology
3,4-Dihydroxyphenylacetic Acid / metabolism
Animals
Aorta, Thoracic / metabolism
Catecholamines / metabolism*
Deamination
Isotope Labeling
Male
Mandelic Acids / metabolism
Methoxyhydroxyphenylglycol / analogs & derivatives,  metabolism
Monoamine Oxidase Inhibitors / pharmacology
Muscle, Smooth / metabolism
Myocardium / metabolism
Neurons / metabolism
Norepinephrine / metabolism
Phenylethyl Alcohol / analogs & derivatives,  metabolism
Rabbits
Rats
Vas Deferens / metabolism
Chemical
Reg. No./Substance:
0/Catecholamines; 0/Mandelic Acids; 0/Monoamine Oxidase Inhibitors; 102-32-9/3,4-Dihydroxyphenylacetic Acid; 10597-60-1/3,4-dihydroxyphenylethanol; 303-75-3/2H-Benzo(a)quinolizin-2-ol, 2-Ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy-; 3343-19-9/dihydroxyphenylethylene glycol; 51-41-2/Norepinephrine; 534-82-7/Methoxyhydroxyphenylglycol; 60-12-8/Phenylethyl Alcohol; 775-01-9/3,4-dihydroxymandelic acid

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