a simple radioenzymatic method for the simultaneous determination of norepinephrine , epinephrine and dopamine in human serum was developed . catecholamines were converted to normetanephrine ( nmn ) , metanephrine ( mn ) , 3-methoxytyramine ( 3-mt ) and their 4-o-methyl isomers by catechol o-methyl transferase with s-adenosylmethionine- ( 3h-methyl ) ( [ 3h ] sam ) .
C0014563
epinephrine
C0025562
metanephrine