Further Investigation of the Metabolism of Two Trace Amines, β-Phenylethylamine and p-Tyramine by Rat Aorta Semicarbazide-Sensitive Amine Oxidase

Guffroy, C.; Boucher, Thierry; Benedetti, Μ. Strolin

doi:10.1007/978-1-4612-5010-4_4

Cited by 4 publications

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“…Although possible clues to the physiological importance of SSAO may be obtained from a clearer perspective of its substrate specificity, and especially of its ability to metabolize endogenous amines, this approach has been complicated to some extent by the discovery first, that a non-physiological substrate, benzylamine, appears to have a lower K, than those naturally-occurring amines so far examined, and second, that the properties of SSAO differ considerably between species. For example, in rat tissues such as the aorta, the K, for benzylamine metabolism (around 5 PM) (Clarke et al 1982) is lower than those values (10-70 PM) reported for the dietary or trace endogenous amines 8-phenylethylamine, tyramine and tryptamine (Guffroy et al 1985;Lyles & Taneja 1987). Under comparable assay conditions, the K, for benzylamine in human aorta is much higher than in the rat (e.g.…”

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confidence: 74%

“…For example, in rat tissues such as the aorta, the K, for benzylamine metabolism (around 5 PM) (Clarke et al 1982) is lower than those values (10-70 PM) reported for the dietary or trace endogenous amines 8-phenylethylamine, tyramine and tryptamine (Guffroy et al 1985;Lyles & Taneja 1987). Under comparable assay conditions, the K, for benzylamine in human aorta is much higher than in the rat (e.g.…”

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confidence: 78%

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Properties of a Semicarbazide-Sensitive Amine Oxidase in Human Umbilical Artery

Precious

Lyles

1988

Journal of Pharmacy and Pharmacology

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The metabolism of some aromatic amines by amine oxidase activities in human umbilical artery homogenates has been studied. The inhibitory effects of clorgyline showed that 5-hydroxytryptamine (5-HT) and tryptamine, 1 mM, were predominantly substrates for monoamine oxidase (MAO) type A, whereas MAO-A and B were both involved in the metabolism of beta-phenylethylamine (PEA), 100 microM, and tyramine, 1 mM. About 20-30% of tyramine and PEA metabolism was resistant to 1 mM clorgyline, but sensitive to inhibition by semicarbazide, 1 mM, indicating the presence of a semicarbazide-sensitive amine oxidase (SSAO). Benzylamine, 1 mM, appeared to be metabolized exclusively by SSAO with a Km (161 microM) at pH 7.8 similar to that found for SSAO in other human tissues. Tyramine and PEA were relatively poor substrates for SSAO, with very high apparent Km values of 17.6 and 13.3 mM, respectively, when determined in the presence of clorgyline, 10(-3) M, added to inhibit any metabolism of those amines by MAO activities. However, kinetic studies with benzylamine indicated that clorgyline, 10(-3) M, also appears to inhibit SSAO competitively such that the true Km values for tyramine and PEA may be about 60% of those apparent values given above. No evidence for the metabolism of 5-HT or tryptamine by SSAO was obtained. The aliphatic amine methylamine was recently shown to be a specific substrate for SSAO in umbilical artery homogenates. We have used benzylamine and methylamine as SSAO substrates in histochemical studies to localize SSAO in tissue sections.(ABSTRACT TRUNCATED AT 250 WORDS)

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confidence: 78%