GLYCOL SULPHATE ESTER FORMATION FROM [¹⁴C]NORADRENALINE IN BRAIN AND THE INFLUENCE OF A COMT INHIBITOR

Abstract— A method is described allowing the identification and separation of the sulphate esters of the glycol metabolites of [ 14 C]noradrenaline injected into the lateral ventricle of the rat. The esters of both the 3,4‐dihydroxy derivative and the 3‐methoxy‐4‐hydroxy derivative are formed in substantial amounts. It is suggested that the quantity of the former may have been underestimated in the past. Contemporaneous administration of pyrogallol, a catechol‐O‐methyl transferase inhibitor, with [ 14 C] noradrenaline leads to a considerable fall in 3‐methoxy‐4‐hydroxyphenylglycol sulphate without a rise in 3‐4‐dihydroxyphenylglycol sulphate although free 3‐4‐dihydroxyphenylglycol rises significantly. It is proposed that the latter may be an index of intraneuronal metabolism of noradrenaline and 3‐methoxy‐4‐hydroxyphenylglycol that of released amine.