Radioenzymatic assay for plasma dihydroxyphenylglycol (DHPG), dihydroxymandelic acid (DOMA) and dihydroxyphenylacetic acid (DOPAC).
An adaptation of the single-isotope radioenzymatic catecholamine assay technique allows simultaneous quantitation of free dihydroxyphenylglycol (DHPG), dihydroxymandelic acid (DOMA), and dihydroxyphenylacetic acid (DOPAC) in small volumes of plasma. Incubation of sample with catechol-O-methyltransferase and S-adenosylmethionine is followed by acidic extractions of metabolites and thin-layer chromatography. O-methylated products of the beta-hydroxylated metabolites DHPG and DOMA are further subjected to periodate cleavage to improve sensitivity. Quantitation by liquid scintillation counting with internal standardization results in a sensitivity of approximately 8, 30 and 70 pg for DHPG, DOMA and DOPAC. Normal values for these three metabolites in resting humans are (mean +/- S.D., pg/ml): 1010 +/- 280 for DHPG, 2090 +/- 720 for DOMA and 3270 +/- 1470 for DOPAC.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis / Q000097:blood*; D006018:Glycols / Q000097:blood*; D006801:Humans; D008333:Mandelic Acids / Q000032:analysis / Q000097:blood*; D008722:Methods; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood*; D010648:Phenylacetates / Q000097:blood*
D006018:Glycols; D008333:Mandelic Acids; D010648:Phenylacetates; D015102:3,4-Dihydroxyphenylacetic Acid; D008734:Methoxyhydroxyphenylglycol; C000989:3,4-dihydroxymandelic acid; C010117:3,4-dihydroxyphenylglycol