Effect of activating adenosine A2B receptors on autophagy during myocardial ischemia-reperfusion in rats: role of PI3K/Akt signaling pathway / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of activating adenosine A2B receptors on autophagy during myocardial ischemia-reperfusion (I/R) and the role of phosphatidylinositol 3-kinase/serine/threonine protein kinase (PI3K/Akt) signaling pathway in rats.Methods:Forty-eight clean-grade healthy male Sprague-Dawley rats, weighing 220-280 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), myocardial I/R group (group I/R), adenosine A2B receptor agonist BAY 60-6583 group (group BAY) and BAY 60-6583+ PI3K inhibitor LY 294002 group (group BAY+ LY). Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery for 30 min followed by 120-min reperfusion.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion in group BAY.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion and LY 294002 10 mg/kg was intraperitoneally injected at 10 min before reperfusion in group BAY+ LY.Blood samples were obtained at the end of reperfusion for determination of concentrations of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in serum (by enzyme-linked immunosorbent assay). The animals were sacrificed, and myocardial tissues were obtained for measurement of the percentage of myocardial infarct size (by Evan Blue and TTC double-staining) and for determination of the expression of microtubule-associated protein 1 light chain 3 (LC3Ⅰ), LC3Ⅱ, Beclin-1 and phosphorylated Akt (p-Akt) (by Western blot). The ratio of LC3Ⅱ/LC3Ⅰ was calculated. Results:Compared with group Sham, the serum LDH and CK-MB concentrations and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group I/R ( P<0.05). Compared with group I/R, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly decreased, the expression of p-Akt was up-regulated, the expression of Beclin-1 and LC3Ⅱ was down-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was decreased in the group BAY ( P<0.05), and no significant change was found in the parameters mentioned above in group BAY+ LY ( P>0.05). Compared with group BAY, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group BAY+ LY ( P<0.05). Conclusion:Activating adenosine A2B receptors can decrease autophagy of myocardial cells during myocardial I/R injury, and the mechanism may be related to activating PI3K/Akt signaling pathway in rats.