Document Detail

Errors introduced by a tritium label in position 8 of catecholamines.
MedLine Citation:
PMID:  2419773     Owner:  NLM     Status:  MEDLINE    
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)
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
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
Aorta, Thoracic / metabolism
Catecholamines / metabolism*
Isotope Labeling
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
Vas Deferens / metabolism
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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