Background: Nuclear factor-κB (NF-κB) is a ubiquitous rapid response transcription factor involved in inflammatory reactions which exerts its effect by expressing cytokines, chemokines, and cell adhesion molecules. Oxidative stress causes NF-κB activation. IRFI 042 is a novel dual vitamin E-like antioxidant and we, therefore, investigated its ability to protect the heart from oxidative stress and to halt the inflammatory response in a model of myocardial ischaemia-reperfusion injury. Methods: Anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5-h reperfusion (MI/R). Sham myocardial ischaemia rats (sham- operated rats) were used as controls. Myocardial necrosis, cardiac output, cardiac and plasma vitamin E levels, myocardial malondialdehyde (MAL), cardiac SOD activity and elastase content (an index of leukocyte infiltration), hydroxyl radical (OH) formation, cardiac amount of mRNA codifying for ICAM-1 (evaluated by the means of reverse transcriptase polymerase chain reaction) and ICAM-1 immunostaining in the at-risk myocardium were investigated. NF-κB activation and the inhibitory protein of NF-κB, I-κBα, were also studied in at-risk myocardium by using electrophoretic mobility shift assay (EMSA) and Western blot analysis, respectively. Results: The ischaemia-reperfusion model produced wide heart necrosis (area at risk-necrotic area = 52 ± 5%; necrotic area-left ventricle = 28 ± 3%), increased cardiac MAL, an index of lipid peroxidation (area at risk = 62.5 ± 3.9 nmol/g tissue; necrotic area = 80.3 ± 5.1 nmol/g tissue), induced tissue neutrophil infiltration, and caused a marked decrease in endogenous antioxidants. Furthermore, myocardial ischaemia plus reperfusion caused in the area at risk peak message for ICAM-1 at 3 h of reperfusion and increased cardiac ICAM-1 immunostaining at 5 h of reperfusion. NF-κB activation was also evident at 0.5 h of reperfusion and reached its maximum at 2 h of reperfusion. I-κBα was markedly decreased at 45 min of occlusion; peak reduction was observed at 1 h of reperfusion and thereafter it was gradually restored. Intraperitoneal administration of IRFI 042 (5, 10, 20 mg/kg, 5 min after reperfusion) reduced myocardial necrosis expressed as a percentage either of the area at risk (18 ± 4%) or the total left ventricle (11 ± 2%), and improved cardiac output. This treatment also limited membrane lipid peroxidation in the area at risk (MAL = 14.3 ± 2.5 nmol/g tissue) and in the necrotic area (MAL = 26.5 ± 3.7 nmol/g tissue), restored the endogenous antioxidants vitamin E and superoxide dismutase, and inhibited detrimental hydroxyl radical formation. Finally, IRFI 042 blocked the activation of NF-κB, reduced cardiac ICAM-1 expression, and blunted tissue elastase content, an index of leukocytes accumulation at the site of injury. Conclusions: Our data suggest that IRFI 042 is cardioprotective during myocardial infarction by limiting reperfusion-induced oxidative stress and by halting the inflammatory response. (C) 2000 Elsevier Science B.V.
- Free radicals
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)