title: Effects of 3-methyladenine on isolated left atria subjected to simulated ischaemia-reperfusion.
abstract: Although autophagy is a prominent feature of myocardial ischaemia and reperfusion, its functional significance is unclear and controversial. In order to gain a deeper insight into the role of autophagy in myocardial ischaemia-reperfusion, we explored the effects of the pharmacological inhibitor of autophagy 3-methyladenine (3-MA). Isolated rat atria subjected to simulated 75-min ischaemia/75-min reperfusion (Is-Rs) in the presence or absence of 3-MA were used. The LC3-II/LC3-I ratio, an indicator of autophagosome formation, did not increase after ischaemia either in the presence or absence of 3-MA, but there was significant enhancement during reperfusion, which was prevented by the presence of 3-MA. The autophagy inhibitor also increased p62 protein, one of the specific substrates degraded through the autophagy-lysosomal pathway. Electron micrographs showed double membrane autophagosome-like structures during reperfusion, which were absent in atria subjected to Is-Rs in the presence of 3-MA. These findings suggest that this agent inhibited the autophagic flux under the present experimental conditions. Inhibition of autophagy during Is-Rs was accompanied by a high incidence of tachyarrhythmias during reperfusion, and a decrease in the maximal inotropic response to β-adrenergic and to calcium stimulation at the end of Is-Rs. Deterioration of mitochondrial morphology and function, without affecting cell viability, was observed in atria subjected to Is-Rs in the presence of 3-MA. The present results suggest an association between the inhibition of autophagy and functional alterations of the cells that have undergone sublethal stress, and have been able to recover in this experimental model of ischaemia-reperfusion.
authors.affiliation: Physiology Unit, Department of Biological Sciences, School of Pharmacy and Biochemistry, University of Buenos Aires and IQUIMEFA-CONICET, Buenos Aires, Argentina.
authors.forename: Romina
authors.initials: R
authors.lastname: Hermann
authors.forename: Débora Elisabet
authors.initials: DE
authors.lastname: Vélez
authors.forename: Tatiana Mariel
authors.initials: TM
authors.lastname: Rusiecki
authors.forename: María de las Mercedes
authors.initials: Mde L
authors.lastname: Fernández Pazos
authors.forename: Victoria Evangelina
authors.initials: VE
authors.lastname: Mestre Cordero
authors.forename: María Gabriela
authors.initials: MG
authors.lastname: Marina Prendes
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Perazzo Rossini
authors.forename: Enrique Alberto
authors.initials: EA
authors.lastname: Savino
authors.forename: Alicia
authors.initials: A
authors.lastname: Varela
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D001343:Autophagy / Q000187:drug effects / Q000502:physiology; D005260:Female; D006325:Heart Atria / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
chemical_list: C025946:3-methyladenine; D000225:Adenine
keywords: 3-methyladenine; atria; autophagy; simulated ischaemia-reperfusion