title: Postconditioning induces an anti-apoptotic effect and preserves mitochondrial integrity in isolated rat hearts.
abstract: Postconditioning (PostC) may limit mitochondrial damage and apoptotic signaling. We studied markers of apoptosis and mitochondrial protection in isolated rat hearts, which underwent a) perfusion without ischemia (Sham), b) 30-min ischemia (I) plus 2-hour reperfusion (R), or c) PostC protocol (5 intermittent cycles of 10-s reperfusion and 10-s ischemia immediately after the 30-min ischemia). Markers were studied in cytosolic (CF) and/or mitochondrial (MF) fractions. In CF, while pro-apoptotic factors (cytochrome c and caspase-3) were reduced, the anti-apoptotic markers (Bcl-2 and Pim-1) were increased by PostC, compared to the I/R group. Accordingly, phospho-GSK-3beta and Bcl-2 levels increased in mitochondria of PostC group. Moreover, I/R reduced the level of mitochondrial structural protein (HSP-60) in MF and increased in CF, thus suggesting mitochondrial damage and HSP-60 release in cytosol, which were prevented by PostC. Electron microscopy confirmed that I/R markedly damaged cristae and mitochondrial membranes; damage was markedly reduced by PostC. Finally, total connexin-43 (Cx43) levels were reduced in the CF of the I/R group, whereas phospho-Cx43 level resulted in higher levels in the MF of the I/R group than the Sham group. PostC limited the I/R-induced increase of mitochondrial phospho-Cx43. Data suggest that PostC i) increases the levels of anti-apoptotic markers, including the cardioprotective kinase Pim-1, ii) decreases the pro-apoptotic markers, e.g. cytochrome c, iii) preserves the mitochondrial structure, and iv) limits the migration of phospho-Cx43 to mitochondria.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Penna
authors.forename: Maria-Giulia
authors.initials: MG
authors.lastname: Perrelli
authors.forename: Stefania
authors.initials: S
authors.lastname: Raimondo
authors.forename: Francesca
authors.initials: F
authors.lastname: Tullio
authors.forename: Annalisa
authors.initials: A
authors.lastname: Merlino
authors.forename: Francesca
authors.initials: F
authors.lastname: Moro
authors.forename: Stefano
authors.initials: S
authors.lastname: Geuna
authors.forename: Daniele
authors.initials: D
authors.lastname: Mancardi
authors.forename: Pasquale
authors.initials: P
authors.lastname: Pagliaro