Effects of postconditioning with α7 nicotinic acetylcholine receptor agonist and ischemia on myocardial ischemia-reperfusion injury in rats

Abstract

Objective To investigate the effects of postconditioning with α7 nicotinic acetylcholine receptor (α7nAChR) agonist and ischemia on myocardial ischemia-reperfusion (IR) injury in rats. Methods Fifty adult male SD rats weighing 290-320 g were randomly divided into 5 groups ( n = 10 each): Ⅰ sham operation group, Ⅱ IR group, Ⅲ ischemic postconditioning group, Ⅳ α7nAChR agonist postconditioning group and Ⅴpostconditioning with α7nAChR agonist and ischemia group. Myocardial I/R was induced by ligation of anterior descending branch of left coronary artery for 30 min followed by 1 80 min of reperfusion. In group] the anterior descending branch was only exposed but not ligated. In group Ⅲ the hearts were subjected to 3 episodes of 10 second ischemia at 10 second intervals at the end of 30 min ischemia before 180 min reperfusion, Intraperitoneal PNU282987 2.4 mg/kg was injected at the end of 30 min ischemia before 180 min reperfusion in group Ⅳ and Ⅴ .Blood samples were taken from right internal jugular vein at 180 min of reperfusion. Then the rats were killed and hearts removed to determine the concentrations of serum cardiac troponin-I (cTnI), TNF-α and high-mobility group box 1 (HMGB1) by ELISA. The infarction size was measured by Evans blue and triphenyltetrazolium chloride staining. Results The infarction size was significantly larger in the other groups and concentrations of serum cTrI, TNF-α and HMGB1 were significantly higher in group Ⅱ than in group Ⅰ ( P ＜ 0.05). The infarction size was significantly smaller and concentrations of serum cTnI, TNF-α and HMGBI were significantly lower in group Ⅲ, Ⅴ than in group Ⅱ (P ＜ 0.05). The infarction size was significantly smaller in group Ⅴ and concentrations of serum cTnI, TNF-α and HMGB1 were significantly lower in group Ⅳ and Ⅴ than in group Ⅲ (P ＜0.05). The infarction size was significantly smaller and concentrations of serum cTnI, TNF-α and HMGB1 were significantly lower in group Ⅴ than in group Ⅳ ( P ＜ 0.05 ). Conclusion Postconditioning with α7nAChR agonist and ischemia can reduce myocardial I/R injury and the efficacy is better than that of α7nAChR agonist postconditioning or ischemic postconditioning alone. Key words: Receptors, nicotinic; Myocardial reperfusion injury; Ischemic postconditioning