Monoamine oxidase (MAO; E.C. 1.4.3.4) characteristics of platelets influenced by in vitro and in vivo ethanol on alcoholics and on control subjects.
Ethanol (ETOH) in vitro displays a competitive inhibition of human platelet MAO-B with a Ki of 270 +/- 30 mM. Lineweaver-Burk analyses with 6 substrate concentrations (5-160 microM kynuramine) in the presence or absence of 200 mM ETOH were performed with platelets of alcoholics before withdrawal (Alc day 1), one week (Alc day 8) and 3 months (Alc mon 3) after withdrawal as well as in control subjects without and after ETOH intake. In all groups the Km increases highly significantly (p < 0.001) but the Vmax is unchanged by the presence of ETOH in vitro supporting the view of a competitive inhibition in each group. The Vmax of Alc day 1 is significantly 25% decreased, of Alc day 8 unchanged and of Alc mon 3 nonsignificantly 19% decreased in comparison with the controls. The increase of the Km in the presence of 200 mM ETOH is significantly 15% reduced in Alc day 1 and 9% in Alc day 8 but unchanged in Alc mon 3 compared with the controls.
May
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Department of Neuropsychopharmacology, Free University, Berlin, Federal Republic of Germany.
Rommelspacher
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D000437:Alcoholism / Q000097:blood* / Q000201:enzymology*; D001792:Blood Platelets / Q000201:enzymology*; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D008995:Monoamine Oxidase / Q000097:blood*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D012016:Reference Values; D013375:Substance Withdrawal Syndrome / Q000097:blood / Q000201:enzymology
D008996:Monoamine Oxidase Inhibitors; D000431:Ethanol; D008995:Monoamine Oxidase