title: Inhibition of myocardial apoptosis by postconditioning is associated with attenuation of oxidative stress-mediated nuclear factor-kappa B translocation and TNF alpha release.
abstract: Oxidative stress-stimulated nuclear factor-kappa B (NF-kappa B) activation has been associated with rapid transcription of TNF-alpha and induction of apoptosis. This study tested the hypothesis that postconditioning (Postcon) reduces myocardial apoptosis and inhibits translocation of NF-kappa B and release of TNF-alpha secondary to an attenuation of oxidant generation during reperfusion. Anesthetized rats were subjected to 30 min of ischemia and 3 h of reperfusion and divided randomly to Control or Postcon (three cycles of 10-s reperfusion and 10-s reocclusion applied at the onset of reperfusion) group, respectively. Relative to Control, Postcon reduced the plasma malondialdehyde (1.21 +/- 0.08 vs. 0.8 +/- 0.06* microM/mL) and decreased the generation of superoxide radical in area at risk myocardium (dihydroethidium staining). Compared with Control, Postcon also inhibited translocation of NF-kappa B to nuclei (167% +/- 21% vs. 142% +/- 18%*), decreased the level of plasma TNF-alpha (1,994 +/- 447 vs. 667 +/- 130* pg/mL), and inhibited caspase-3 activity (0.57% +/- 0.1% vs. 0.21% +/- 0.1%*). The number of apoptotic cells (percent total nuclei) in ischemic myocardium was reduced (20% +/- 1% vs. 11% +/- 2%*), consistent with reduced appearance of DNA fragmentation. To support whether oxidant generation is important in the triggering of cytokine release and apoptosis, N-acetylcysteine (NAC), a potent antioxidant agent, was administered before ischemia and at reperfusion. Treatment with NAC inhibited superoxide radical generation and decreased plasma malondialdehyde to a comparable level to that in Postcon, concomitant with an inhibition of NF-kappa B expression (42% +/- 8%*) and reduction of release of TNF-alpha (231 +/- 72* pg/mL). Caspase-3 activity (0.33% +/- 0.1%*) and apoptotic cells (12% +/- 1%*) were also comparably reduced by NAC. These data suggest that Postcon attenuates myocardial apoptosis, reduces caspase-3 activity, and is potentially mediated by inhibiting oxidant-activated NF-kappa B-TNF-alpha signaling pathway. *P < 0.05 Postcon and NAC vs. Control.
authors.affiliation: Cardiothoracic Research Laboratory, The Carlyle Fraser Heart Center/Crawford Long Hospital, Emory University School of Medicine, Atlanta, GA 30308-2225, USA.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kin
authors.forename: Ning-Ping
authors.initials: NP
authors.lastname: Wang
authors.forename: James
authors.initials: J
authors.lastname: Mykytenko
authors.forename: James
authors.initials: J
authors.lastname: Reeves
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Deneve
authors.forename: Rong
authors.initials: R
authors.lastname: Jiang
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Zatta
authors.forename: Robert A
authors.initials: RA
authors.lastname: Guyton
authors.forename: Jakob
authors.initials: J
authors.lastname: Vinten-Johansen
authors.forename: Zhi-Qing
authors.initials: ZQ
authors.lastname: Zhao
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D053938:DNA Fragmentation / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D019194:Ischemic Preconditioning; D008297:Male; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D016166:Free Radical Scavengers; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; C505410:Casp3 protein, rat; D053148:Caspase 3; D000111:Acetylcysteine