title: Ischemia alone is sufficient to induce TNF-alpha mRNA and peptide in the myocardium.
abstract: Over-production of tumor necrosis factor-alpha (TNF-alpha) following myocardial ischemia-reperfusion contributes to cardiac dysfunction, and anti-TNF-alpha has therapeutic potential for myocardial protection in cardiac surgery with obligatory ischemia. It remains unclear, however, whether myocardial TNF-alpha production occurs during ischemia and whether cardiac myocytes constitute a source of myocardial TNF-alpha. Ischemia alone has been shown to activate myocardial NF-kappaB. We hypothesized that ischemia alone is sufficient to induce myocardial TNF-alpha gene expression and peptide synthesis. We examined TNF-alpha production and NF-kappaB activation in the isolated rat heart subjected to global normothermic ischemia. Myocardial ischemia resulted in rapid IkappaB-alpha degradation and NF-kappaB activation. Immunofluorescence staining detected NF-KB intranuclear translocation primarily in myocardial interstitial cells. Ischemia alone induced a time-dependent increase in myocardial TNF-alpha. TNF-alpha peptide increased to 20.3+/-3.0 pg/mg after 25 min of ischemia (P < 0.05 vs 8.9+/-2.0 pg/mg in perfusion control). TNF-alpha was also localized to myocardial interstitial cells. Increased TNF-alpha peptide level correlated with TNF-alpha mRNA expression. We conclude that ischemia alone induces TNF-a gene expression and peptide synthesis in the myocardium that are associated with NF-kappaB activation. Non-myocytes constitute the main source of myocardial TNF-alpha following ischemia. The results suggest that therapeutic strategies attempting to decrease myocardial TNF-alpha production need to be applied before or in the early phase of ischemia.
authors.affiliation: Department of Surgery, University of Colorado Health Sciences Center, Denver 80262, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Shames
authors.forename: Hazel H
authors.initials: HH
authors.lastname: Barton
authors.forename: Leonid L
authors.initials: LL
authors.lastname: Reznikov
authors.forename: Charles B
authors.initials: CB
authors.lastname: Cairns
authors.forename: Anirban
authors.initials: A
authors.lastname: Banerjee
authors.forename: Alden H
authors.initials: AH
authors.lastname: Harken
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Meng
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha