Effect of tumor necrosis factor-alpha on ventricular arrhythmias in rats with acute myocardial infarction in vivo

BACKGROUND: Acute myocardial infarction (AMI) is an acute cardiovascular emergency. This study was undertaken to assess the effect of tumor necrosis factor-alpha (TNF-alpha) on ventricular arrhythmias induced by AMI in rats in vivo. METHODS: Two hundred and forty male Wistar rats were randomized into a sham-operation group, an AMI group, and a recombinant human tumor necrosis factor receptor: Fc fusion protein(rhTNFR:Fc) group. Acute anterior wall myocardial infarction was produced in the AMI group by ligating the left anterior descending coronary artery (LAD), and there was no ligation but operation in the sham-operation group. The rhTNFR: Fc group was treated with rhTNFR: Fc(10 mg/kg), a TNF-alpha antagonist, 24 hours before LAD ligation. The spontaneous and induced programmed electrical stimulation ventricular arrhythmias were recorded at baseline and 10 minutes, 20 minutes, 30 minutes, 60 minutes, 3 hours, 6 hours and 12 hours after ligation. At the same time the protein and mRNA expression levels of TNF-alpha among different groups were detected by histochemistry and real-time fluorescent quantitative PCR. RESULTS: Expression of TNF-alpha increased markedly from 10 minutes after infarction, peaked at 20-30 minutes, and returned to baseline gradually in the AMI group and rhTNFR: Fc group. The time-windows of spontaneous and induced ventricular arrhythmias were similar. Compared with the AMI group, the rhTNFR: Fc group showed a lesser expression of TNF-alpha protein and a lower incidence of ventricular arrhythmias (P<0.05). There was no obvious change in the sham-operation group. CONCLUSION: The expression of TNF-alpha induced by AMI could contribute to the onset of ventricular arrhythmias.