title: Cross-functioning between the extraneuronal monoamine transporter and multidrug resistance protein 1 in the uptake of adrenaline and export of 5-(glutathion-S-yl)adrenaline in rat cardiomyocytes.
abstract: Isolated heart cells are highly susceptible to the toxicity of catecholamine oxidation products, namely, to catecholamine-glutathione adducts. Although cellular uptake and/or efflux of these products may constitute a crucial step, the knowledge about the involvement of transporters is still very scarce. This work aimed to contribute to the characterization of membrane transport mechanisms, namely, extraneuronal monoamine transporter (EMT), the multidrug resistant protein 1 (MRP1), and P-glycoprotein (P-gp) in freshly isolated cardiomyocytes from adult rats. These transporters may be accountable for uptake and/or efflux of adrenaline and an adrenaline oxidation product, 5-(glutathion-S-yl)adrenaline, in cardiomyocyte suspensions. Our results showed that 5-(glutathion-S-yl)adrenaline efflux was mediated by MRP1. Additionally, we demonstrated that the adduct formation occurs within the cardiomyocytes, since EMT inhibition reduced the intracellular adduct levels. The classical uptake2 transport in rat myocardial cells was inhibited by the typical EMT inhibitor, corticosterone, and surprisingly was also inhibited by low concentrations of another drug, a well-known P-gp inhibitor, GF120918. The P-gp activity was absent in the cells since P-gp-mediated efflux of quinidine was not blocked by GF120918. In conclusion, this work showed that freshly isolated cardiomyocytes from adult rats constitute a good model for the study of catecholamines and catecholamines metabolites membrane transport. The cardiomyocytes maintain EMT and MRP1 fully active, and these transporters contribute to the formation and efflux of 5-(glutathion-S-yl)adrenaline. In the present experimental conditions, P-gp activity is absent in the isolated cardiomyocytes.
authors.affiliation: REQUIMTE (Rede de Qumica e Tecnologia), Toxicology Department, Faculty of Pharmacy, University of Porto, Porto, Portugal
authors.forename: Vera Marisa
authors.initials: VM
authors.lastname: Costa
authors.forename: Lusa Maria
authors.initials: LM
authors.lastname: Ferreira
authors.forename: Paula Srio
authors.initials: PS
authors.lastname: Branco
authors.forename: Flix
authors.initials: F
authors.lastname: Carvalho
authors.forename: Maria Lourdes
authors.initials: ML
authors.lastname: Bastos
authors.forename: Rui Albuquerque
authors.initials: RA
authors.lastname: Carvalho
authors.forename: Mrcia
authors.initials: M
authors.lastname: Carvalho
authors.forename: Fernando
authors.initials: F
authors.lastname: Remio
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000166:Acridines / Q000494:pharmacology; D000818:Animals; D002395:Catecholamines / Q000378:metabolism / Q000633:toxicity; D003345:Corticosterone / Q000494:pharmacology; D003846:Deoxyepinephrine / Q000031:analogs & derivatives* / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism*; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044005:Tetrahydroisoquinolines / Q000494:pharmacology; D000099254:Organic Cation Transporter 3
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000166:Acridines; D002395:Catecholamines; D003345:Corticosterone; D003846:Deoxyepinephrine; D004837:Epinephrine; D005978:Glutathione; D027701:Organic Cation Transport Proteins; D044005:Tetrahydroisoquinolines; D000099254:Organic Cation Transporter 3; C096088:5-(glutathion-S-yl)methyldopamine; C083501:Elacridar