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Estimation of the Turnover of 3‐Methoxytyramine in the Rat Striatum by HPLC with Electrochemical Detection: Implications for the Sequence in the Cerebral Metabolism of Dopamine
Author(s) -
Westerink B. H. C.,
Spaan S. J.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb08634.x
Subject(s) - homovanillic acid , dopamine , chromatography , chemistry , sephadex , high performance liquid chromatography , striatum , catechol , dopaminergic , endocrinology , biochemistry , enzyme , biology , receptor , serotonin
A highly sensitive method for the determination of 3‐methoxytyramine (3‐MT) in nervous tissue is described. The method is based on a rapidly performed isolation of 3‐MT on small columns of Sephadex G 10, followed by reverse‐phase high‐performance liquid chromatography in conjunction with a rotating disk electrochemical detector. The detection limit of the assay (0.5–1 pmol/tissue sample) is about 10% of control value for microwave‐killed rats. 3‐MT as well as dopamine could be quantified in the same chromatographic run. Inhibition of catechol‐ O ‐methyl transferase with tropolone resulted in an exponential decline of 3‐MT. From this exponential decline a turnover rate for 3‐MT of 1.9 nmol/g/h was calculated. In the same group of rats the turnover rate of homovanillic acid was 9.1 nmol/g/h. From these data it is concluded that in the rat striatum about 80% of homovanillic acid is formed from 3,4‐dihydroxyphenylacetic acid and 20% from 3‐MT.