An enzymatic assay for octopamine and other beta-hydroxylated phenylethylamines.

Abstract

The conversion of β-hydroxylated amines to their N-methyl derivatives by partially purified bovine adrenal phenylethanolamine N-methyltransferase provides a convenient method of assaying for compounds such as octopamine and phenylethanolamine. C 14 -S- adenosylmethionine is used as the methyl donor in a reaction which is specific for β-hydroxylated amines. The N-methyl derivatives formed are extracted into a mixture of toluene and isoamyl alcohol at an alkaline pH, and their identity has been confirmed by chromatography. Octopamine accumulation has been measured in rat organs after the inhibition of monoamine oxidase, and the conversion of injected tyramine to octopamine has been studied. Minor modifications of the assay procedure make it suitable for the measurement of phenylethanolamine, and this compound has been measured in rat organs after the administration of phenylethylamine.