title: Metabolism is required for the expression of ecstasy-induced cardiotoxicity in vitro.
abstract: Cardiovascular complications associated with 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) abuse have increasingly been reported. The indirect effect of MDMA mediated by a sustained high level of circulating biogenic amines may contribute to the cardiotoxic effects, but other factors, like the direct toxic effects of MDMA and its metabolites in cardiac cells, remain to be investigated. Thus, the objective of the present in vitro study was to evaluate the potential cardiotoxic effects of MDMA and its major metabolites 3,4-methylenedioxyamphetamine (MDA), N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA), and alpha-methyldopamine (alpha-MeDA) using freshly isolated adult rat cardiomyocytes. The cell suspensions were incubated with these compounds in the final concentrations of 0.1, 0.2, 0.4, 0.8, and 1.6 mM for 4 h. alpha-MeDA, N-Me-alpha-MeDA, and their respective aminochromes (oxidation products) were quantified in cell suspensions by HPLC-DAD. The toxic effects were evaluated at hourly intervals for 4 h by measuring the percentage of cells with normal morphology, glutathione (GSH), and glutathione disulfide (GSSG); intracellular Ca(2+), ATP, and ADP; and the cellular activities of glutathione peroxidase, glutathione reductase, and glutathione-S-transferase. No toxic effects were found after exposure of rat cardiomyocytes to MDMA or MDA at any of the tested concentrations for 4 h. In contrast, their catechol metabolites N-Me-alpha-MeDA and alpha-MeDA induced significant toxicity in rat cardiomyocytes. The toxic effects were characterized by a loss of normal cell morphology, which was preceded by a loss of GSH homeostasis due to conjugation of GSH with N-Me-alpha-MeDA and alpha-MeDA, sustained increase of intracellular Ca(2+) levels, ATP depletion, and decreases in the antioxidant enzyme activities. The oxidation of N-Me-alpha-MeDA and alpha-MeDA into the toxic compounds N-methyl-alpha-methyldopaminochrome and alpha-methyldopaminochrome, respectively, was also verified in cell suspensions incubated with these MDMA metabolites. The results obtained in this study provide evidence that the metabolism of MDMA into N-Me-alpha-MeDA and alpha-MeDA is required for the expression of MDMA-induced cardiotoxicity in vitro, being N-Me-alpha-MeDA the most toxic of the studied metabolites.
authors.affiliation: REQUIMTE, Serviço de Toxicologia, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, 4099/030 Porto, Portugal. mariacarvalho@ff.up.pt
authors.forename: Márcia
authors.initials: M
authors.lastname: Carvalho
authors.forename: Fernando
authors.initials: F
authors.lastname: Remião
authors.forename: Nuno
authors.initials: N
authors.lastname: Milhazes
authors.forename: Fernanda
authors.initials: F
authors.lastname: Borges
authors.forename: Eduarda
authors.initials: E
authors.lastname: Fernandes
authors.forename: Maria do Céu
authors.initials: Mdo C
authors.lastname: Monteiro
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Gonçalves
authors.forename: Vítor
authors.initials: V
authors.lastname: Seabra
authors.forename: Francisco
authors.initials: F
authors.lastname: Amado
authors.forename: Félix
authors.initials: F
authors.lastname: Carvalho
authors.forename: Maria Lourdes
authors.initials: ML
authors.lastname: Bastos
mesh_terms: D015104:3,4-Methylenedioxyamphetamine / Q000378:metabolism / Q000633:toxicity*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003846:Deoxyepinephrine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D008660:Metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D018490:Serotonin Agents / Q000378:metabolism / Q000633:toxicity*; D013997:Time Factors
chemical_list: D018490:Serotonin Agents; D015104:3,4-Methylenedioxyamphetamine; C023492:alpha-methyldopamine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D005978:Glutathione; D003846:Deoxyepinephrine; D002118:Calcium; D019803:Glutathione Disulfide