Functional and cardioprotective effects of simultaneous and individual activation of protein kinase A and Epac.
Functional and cardioprotective effects of simultaneous and individual activation of protein kinase A and Epac.
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DOI：
10.1111/bph.13709
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发表时间：
2017-03
影响因子：
7.3
通讯作者：
Suleiman MS
中科院分区：
文献类型：
--
作者：
Khaliulin I;Bond M;James AF;Dyar Z;Amini R;Johnson JL;Suleiman MS
心肌cAMP升高对缺血/再灌注(I/R)损伤具有心脏保护作用。CAMP激活两条独立的信号通路：PKA和EPAC。本研究探讨了激活PKA和/或EPAC对心脏的影响及其在心肌缺血再灌注保护中的作用。雄性大鼠的心脏用于测定PKA和PKC的激活，或以Langendorff模式灌流以分离心肌细胞，或用于监测基础水平和全脑缺血30min再灌流2h后的功能活动。观察再灌注期的功能恢复情况和心肌损伤情况(乳酸脱氢酶释放和心肌梗死面积)。在存在或不存在PKA、EPAC和PKC抑制剂的情况下，使用细胞通透性cAMP类似物诱导PKA和/或EPAC在灌流心脏中的激活。用H9C2细胞和心肌细胞检测EPAC的激活及其对钙离子瞬变的影响。选择性地激活PKA或EPAC均可触发正性变力作用，当这两个通路同时激活时，这种作用显著增强。只有联合激活PKA和EPAC对心肌I/R损伤有明显的保护作用。伴随着PKCε的激活，并被PKA、EPAC或PKC的抑制剂抑制。同时激活PKA和EPAC可产生相加的变力作用，对I/R损伤具有最佳和显著的心脏保护作用。后一种作用是通过激活PKCε来实现的。这项工作介绍了一种新的治疗方法和靶点，以保护心脏免受心脏损伤。
Myocardial cAMP elevation confers cardioprotection against ischaemia/reperfusion (I/R) injury. cAMP activates two independent signalling pathways, PKA and Epac. This study investigated the cardiac effects of activating PKA and/or Epac and their involvement in cardioprotection against I/R. Hearts from male rats were used either for determination of PKA and PKC activation or perfused in the Langendorff mode for either cardiomyocyte isolation or used to monitor functional activity at basal levels and after 30 min global ischaemia and 2 h reperfusion. Functional recovery and myocardial injury during reperfusion (LDH release and infarct size) were evaluated. Activation of PKA and/or Epac in perfused hearts was induced using cell permeable cAMP analogues in the presence or absence of inhibitors of PKA, Epac and PKC. H9C2 cells and cardiomyocytes were used to assess activation of Epac and effect on Ca2+ transients. Selective activation of either PKA or Epac was found to trigger a positive inotropic effect, which was considerably enhanced when both pathways were simultaneously activated. Only combined activation of PKA and Epac induced marked cardioprotection against I/R injury. This was accompanied by PKCε activation and repressed by inhibitors of PKA, Epac or PKC. Simultaneous activation of both PKA and Epac induces an additive inotropic effect and confers optimal and marked cardioprotection against I/R injury. The latter effect is mediated by PKCε activation. This work has introduced a new therapeutic approach and targets to protect the heart against cardiac insults.