3-Methoxytyramine as an indicator of dopaminergic manipulation in the equine athlete.
The influence of sampling variables on the concentration of the dopamine metabolites 3-methoxytyramine (3MT), dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) was examined in equine urine. A logarithmic transformation of the data for all horses gave distribution which approximated the normal distributions for each metabolite. The mean urinary concentration of 3 MT in horses was 214 ng/mL and the application of a threshold with a probability of 1 in 10,000 gave an actionable level of 4 microg/mL. Environmental variables were not forensically significant in determining the population distribution. HVA was not found to be a reliable indicator of dopamine or levodopa administration.
Racing Analytical Services Limited, 400 Epsom Road, Flemington, Vic. 3031, Australia. pwynne@sge.com
Paul M
PM
Wynne
John H
JH
Vine
R Gary
RG
Amiet
D000818:Animals; D004298:Dopamine / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000652:urine*; D004300:Doping in Sports; D006736:Horses
C001746:3-methoxytyramine; D004298:Dopamine