吡格列酮对缺血-再灌注大鼠心肌梗死面积和线粒体ATP敏感性钾通道的影响

目的 观察PPARγ激动剂吡格列酮对在体大鼠心肌缺血-再灌注心肌梗死面积、缺血面积及线粒体ATP敏感性钾通道(mitoKATP)影响,探讨其可能机制.方法 健康雄性SD大鼠54只,分为实验一和实验二完成.在实验一中24只大鼠随机分4组,每组6只:(1)假手术对照组(SO)行冠脉穿线但不结扎,4 h后取出心脏;(2)单纯I/R组于I/R前24 h由尾静脉注入0.9%生理盐水,开胸结扎冠脉前降支30 min,松解后再灌注4 h;(3)5-HD+吡格列酮组(5-HD+Pio)于I/R前24 h由尾静脉缓慢注入mitoKATP阻滞剂5羟基葵酸(10 ms/ks),30 min后再缓慢注入吡格列酮(3 mg/kg),持续5 min,24 h后处理同I/R组;(4)吡格列酮预处理组(Pio)于缺血-再灌注前24 h只注入吡格列酮(3 mg/kg),持续5min,余处理同(3).后三组结扎前降支30 min、再灌注4 h后取出心脏.Western blot法测P38MAPK、JNK和NFκB P65蛋白水平的表达.在实验二中SD大鼠30只,分为SO组、I/R组、Pio组、5-HD+Pio组及单纯5-HD组(于I/R前24 h由尾静脉缓慢注入5羟基葵酸10 mg/kg余同I/R组),再灌注4 h后,测心肌缺血及梗死范围.多组间比较采用单因素方差分析(SNK-q检验),采用SPSS 11.0软件系统分析,P<0.05为差异具有统计学意义.结果 (1)与I/R组(34.93±5.55)%相比,Pio组梗死面积(20.24±3.93%)明显减少(P<0.05),5-HD+Pio组和5-HD与I/R组相比差异无统计学意义(P>0.05);除SO组外,其他各绀间心肌缺血面积差异无统计学意义(P>0.05).与SO组相比,I/R组P38MAPKmRNA、JNK mRNA及P38MAPK、JNKI、JNK2和NFκB P65蛋白表达水平明显增加(P<0.05);与I/R组相比Pio绀能抑制以上水平的过度表达(P<0.05).结论 吡格列酮预处理可通过减少心肌梗死范围起到抗缺血-再灌注损伤作用,该保护作用可能与开放线粒体ATP敏感性钾通道及下调P38MAPK、JNK及NF-κB P65蛋白表达活性有关.

The effects of preconditioning with pioglitazone on infarct size and mitochondrial ATP-sensitive potassium channel in rats with ischemia-reperfusion

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.