Effects of acidic reperfusate medium on apoptosis of myocardial endopasmic reticulum stress

Abstract

Objective To determine the effect of acidic reperfusion solution on apoptosis of myocardial endoplasmic reticulum stress (ERS).Methods Twenty-four SD rats were randomly divided into 3 groups (n =8 each).In control group (C),the isolated heart was only reperfused 180 min with pH 7.4 HEPES-KH solution.In ischemia/reperfusion (I/R) group,the isolated heart was reperfused 20 min and then subjected to ischemia for 60 min followed by 100 min reperfusion with pH 7.4 HEPES-KH solution.In experiment group (E),the isolated heart was reperfused 20 min with pH 7.4 HEPES-KH solution and then subjected to ischemia for 60 min,followed by reperfusion with pH6.8,pH 7.1 and pH 7.4 HEPES-KH solution for 5 min,5 min,and 90 min,respectively.Cardiac troponin I (cTnI) concentration,apoptosis of myocardial cells,the expression levels of calreticulin (CRT) mRNA,the expression levels of Caspase-12 and CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) were assayed.Results As compared with C group (1.3 ±0.4,3.7 ± 1.1,0.48 ±0.04,0.12 ±0.02,0.08 ±0.01),in I/R group and E group,the cTnI concentration (12.5 ±3.2,6.7 ± 1.7),apoptosis rate (27.9 ±5.3,18.0 ± 3.9),expressions of CRT mRNA (1.03 ± 0.06,0.79 ± 0.05),Caspase-12 (0.35 ± 0.05,0.24 ± 0.03) and CHOP (0.19 ±0.04,0.13 ±0.03) were increased significantly (P ＜0.01).All the indexes in E group were significantly reduced as compared with I/R group (P ＜0.01).Conclusion Acidic reperfusion may protect the heart against I/R injury and alleviate ERS-mediated apoptosis by inhibiting excessive ERS during I/R. Key words: Myocardial protection; Acidic reperfusion fluid; Endopasmic reticulum stress; Apoptosis ; Reperfusion injury