ABSTRACT
Objective To observe the effects of preconditioning with pioglitazone on infarct size and mito-chondrial ATP-sensitive potassium channel in rats with ischemia-repedusion, and to explore its possible mecha-nism. Method The whole experiment was divided into experiment Ⅰ and Ⅱ. In experiment Ⅰ, 24 rats were ran-domly divided into four groups (6 rats in each group): (1)Sham-operated (SO) group: the coronary artery of rat was threading without hgation, and the heart was removed by cutting immediately 4 hours later; (2) Isehemia-reperfusion (I/R) group: the rats were administered with 0.9% saline intravenously via caudal vein at 24 hours before iigating the left anterior descending branch of coronary artery for 30 minutes, and followed by reperfusion for 4 hours; (3)5-hydroxydecanoate plus pioglitazone(5HD+Pio) group: the rats were injected with 10 mg/kg 5-hy-droxydecanoate (the blocker of mitochondrial ATP-sensitive potassium channels,) at 24 hours before ligation, and 30 minutes later, 3 mg/kg pioglitazone was given in 5 minutes, and then the rats were subjected to ischemia for 30 minutes, followed by reperfusion for4 hours; (4)pioglitazone treatment group (Pio): the mrs were given 3 mg/kg pioglitazone at 24 hours before occlusion, and then they were treated as done in the 5HD+Pio group. In I/R, 5HD+Pio and Pio group, the hearts were removed by cutting after reperfusion. Western blotting was used to detect the protein expression of P38MAPK, .INK and NFκB P65. In experiment Ⅱ, 30 rats were randomly divided into five groups: SO, I/R, Pio, 5HD+Pio and 5-HD group (rats were treated as done in the rats of I/R group and were injected with 10 mg/kg 5-bydroxydecanoate 24 h before ischemia/reperfusion),and the size of myocardial in-farction and isehemia were measured after reperfusion. Statistical analyses were performed using SPSS10.0 soft-ware. Multiple comparisons were analyzed by one-way analysis of variance (SNK-q test). P<0.05 was consid-ered statistically significant. Results (1) The infarct size in i/R group was(34.93±5.55)%, while pioglita-zone reduced the infarct size to(20.24±3.93)% (P<0.05). There was no significant difference between I/R and 5-HD±Pio or 5-HD groups (P>0.05). Compared with the sham-operated group, the expression of P38MAPKmRNA, JNKmRNA and protein of P38MAPK, JNK and NFκB P65 in I/R increased (P<0.05). Com-pared with the I/R group, pioglitazone inhibited these undue expressions (P<0.05). Conclusions Pioglitazone could protect the heart from ischemia-reperfusion injury evidenced by reducing infarct size. These protective effects of pioglitazone may be related to opening mitochondrial ATP-seusitive potassium channels or downregulation of JNK and p38 MAPK signaling, leading to the overexpression of NFκB p65 activation.