Title

Method for measuring endogenous 3-O-methyldopa in urine and plasma

Document Type

Journal Article

Publication Date

7-17-1991

Journal

Journal of Chromatography B: Biomedical Sciences and Applications

Volume

568

Issue

1

DOI

10.1016/0378-4347(91)80339-E

Abstract

The present report describes a method using column liquid chromatography with electrochemical detection for assaying concentrations of 3-O-methyldopa in urine and plasma. The technique combines a one-step sample preparation scheme with post-column flow-through electrodes in series, allowing adequate chromatographic separation of 3-O-methyldopa from other endogenous substances in urine. The validity of the method was confirmed by markedly decreased urinary 3-O-methyldopa levels after administration of an inhibitor of catechol-O-methyltransferase to rats, radioactivity in chromatographic fractions corresponding to 3-O-methyldopa in urine of rats undergoing infusion of [3H]-l-DOPA, and correlations between excretion rates of 3-O-methyldopa and catechols in humans. In healthy humans, urinary excretion of 3-O-methyldopa averaged 974 ± 707 (S.D.) nmol per day, and plasma levels of 3-O-methyldopa averaged 89 ± 32 nmol/l. The method should be useful in studies about the metabolism of endogenous and exogenous DOPA. © 1991.

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