Determination of acidic metabolites of biogenic amines in human aqueous humour by gas chromatography--negative ion chemical ionisation mass spectrometry.

The concentrations of acidic metabolites derived from the biogenic amines o-, m-, and p-tyramines (o-, m-, and p-hydroxyphenylacetic acids), p-octopamine/p-synephrine (p-hydroxymandelic acid), and dopamine (homovanillic acid and 3,4-dihydroxyphenylacetic acid) were measured in human aqueous humour obtained from patients undergoing elective surgery for cataract removal or for trabeculectomy as a treatment for chronic open-angle glaucoma. There were no clear differences in the pattern of metabolism of neurotransmitters between the two groups. An unexpected finding was that the o-tyramine metabolite, o-hydroxyphenylacetic acid, was present in aqueous humour.