Monoamine oxidase (MAO; E.C. 22.214.171.124) characteristics of platelets influenced by in vitro and in vivo ethanol on alcoholics and on control subjects
Part of the
Journal of Neural Transmission
book series (NEURAL SUPPL, volume 41)
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 μM 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.
KeywordsMonoamine Oxidase Human Platelet Stud Alcohol ETOH Intake ETOH Intoxication
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Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72: 248–254.PubMedCrossRefGoogle Scholar
Faraj BA, Lenton JD, Kutner M, Camp VM, Stammers TW, Lee SR, Lolies PA, Chandora D (1987) Prevalence of low monoamine oxidase function in alcoholism. Alcoholism: Clin Exp Res 11: 464–467.CrossRefGoogle Scholar
Johnston JP (1968) Some observations upon a new inhibitor of monoamine oxidase in brain tissue. Biochem Pharmacol 17: 1285–1297.PubMedCrossRefGoogle Scholar
Knoll J, Magyar K (1972) Some puzzling pharmacological effects of monoamine oxidase inhibitors. In: Costa E, Sandier M (eds) Advances in biochemical psychophar-macology, vol 5. Raven Press, New York, pp 393–408.Google Scholar
Kraml M (1965) A rapid microfluorimetric determination of monoamine oxidase. Biochem Pharmacol 14: 1684–1686.CrossRefGoogle Scholar
Major LF, Goyer PF, Murphy DL (1981) Changes in platelet monoamine oxidase activity during abstinence. J Stud Alcohol 42: 1052–1057.PubMedGoogle Scholar
Squires RF (1968) Additional evidence for the existence of several forms of mitochondrial monoamine oxidase in the mouse. Biochem Pharmacol 17: 1401–1409.PubMedCrossRefGoogle Scholar
Tabakoff B, Lee JM, De Leon-Jones F, Hoffman PL (1985) Ethanol inhibits the activity of the B form of monoamine oxidase in human platelet and brain tissue. Psychopharmacology 87: 152–156.PubMedCrossRefGoogle Scholar
Tabakoff B, Hoffman PL, Lee JM, Saito T, Willard B, De Leon-Jones F (1988) Differences in platelet enzyme activity between alcoholics and nonalcoholics. N Engl J Med 318: 134–139.PubMedCrossRefGoogle Scholar
von Knorring A-L, Hallman J, von Knorring L, Oreland L (1991) Platelet monoamine oxidase activity in type 1 and type 2 alcoholism. Alc Alcoholism 26: 409–416.Google Scholar
Waldmeier PC, Feiner AE, Tipton KF (1983) The monoamine oxidase inhibiting properties of CGP 11305 A. Eur J Pharmacol 94: 73–83.PubMedCrossRefGoogle Scholar
Wiemer G, Wellstein A, Palm D, Hattingberg HM, Brockmeier D (1982) Properties of agonist binding at the β-adrenoceptor of the rat reticulocyte. Naunyn Schmiedebergs Arch Pharmacol 321: 11–19.PubMedCrossRefGoogle Scholar
Yates WR, Wilcox J, Knudson R, Myers C, Kelly MW (1990) The effect of gender and subtype on platelet MAO in alcoholism. J Stud Alcohol 51: 463–467.PubMedGoogle Scholar