Activation of mitochondrial ATP-sensitive K+ channel for cardiac protection against ischemic injury is dependent on protein kinase C activity
Activation of mitochondrial ATP-sensitive K+ channel for cardiac protection against ischemic injury is dependent on protein kinase C activity
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DOI：
10.1161/01.res.85.8.731
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发表时间：
1999-10-15
影响因子：
20.1
通讯作者：
Ashraf, M
中科院分区：
文献类型：
--
作者：
Wang, YG;Hirai, K;Ashraf, M
蛋白激酶C （PKC）在缺血和Ca2+预处理过程中参与第二信使信号级联。鉴于线粒体ATP敏感的K+ (mitoK(ATP))通道的药理激活也模拟了预处理，PKC激活和mitoK（ATP）通道的联系机制仍有待建立。我们假设PKC活性对mitoK（ATP）通道的打开很重要。为了检验这一点，在缺血/再灌注（I/R）模型中，将mitoK（ATP）通道的特异性打开剂二氮氧化物与PKC的亚细胞分布结合使用。langendorff灌注大鼠心脏缺血40分钟，再灌注30分钟。评估mitoK（ATP）通道激活和其他干预措施对缺血心脏功能、生化和病理变化的影响。用二氮氧化合物治疗的心脏，IIR后左室舒张末压和冠状动脉血流明显改善；乳酸脱氢酶释放量也显著降低。与未处理的缺血对照心脏相比，二氮唑处理心脏的形态学保存较好。二氮氧化合物对缺血损伤的有益作用与Ca2+预处理相似。在缺血期间，在二氮氧化物预处理或二氮氧化物持续存在期间，给予有效的mitoK（ATP）通道阻滞剂5-羟乙酸钠或PKC抑制剂chelerythrine或calphostin C，完全消除了二氮氧化物对VR损伤的有益作用，在二氮氧化物治疗期间，通过维拉帕米抑制l型Ca2+通道阻断Ca2+进入也完全逆转了二氮氧化物在I/R期间的有益作用。PKC-alpha易位到肌膜，PKC-delta易位到线粒体和嵌层椎间盘，PKC-epsilon易位到嵌层椎间盘。通过免疫共聚焦显微镜对线粒体分布与四甲基罗丹明乙酯（TMRE）和PKC异构体的共定位研究发现PKC-delta抗体特异性染色线粒体。二氮唑处理的心脏中ATP显著增加。此外，数据表明PKC对线粒体的激活和易位似乎对mitoK（ATP）通道介导的保护很重要。
Protein kinase C (PKC) is involved in the second messenger signaling cascade during ischemic and Ca2+ preconditioning. Given that the pharmacological activation of mitochondrial ATP-sensitive K+ (mitoK(ATP)) channels also mimics preconditioning, the mechanisms linking PKC activation and mitoK(ATP) channels remain to be established. We hypothesize that PKC activity is important for the opening of the mitoK(ATP) channel. To examine this, a specific opener of the mitoK(ATP) channel, diazoxide, was used in conjunction with subcellular distribution of PKC in a model of ischemia/reperfusion (I/R). Langendorff-perfused rat hearts were subjected to 40-minute ischemia followed by 30-minute reperfusion. Effects of activation of the mitoK(ATP) channel and other interventions on functional, biochemical, and pathological changes in ischemic hearts were assessed. In hearts treated with diazoxide, left ventricular end-diastolic pressure and coronary flow were significantly improved after IIR; lactate dehydrogenase release was also significantly decreased. The morphology was well preserved in diazoxide-treated hearts compared with nontreated ischemic control hearts. The salutary effects of diazoxide on the ischemic injury were similar to those of Ca2+ preconditioning. Administration of sodium 5-hydroxydecanoate, an effective blocker of the mitoK(ATP) channel, or chelerythrine or calphostin C, an inhibitor of PKC, during diazoxide pretreatment or during continuous presence of diazoxide in the ischemic period, completely abolished the beneficial effects of the diazoxide on the VR injury, Blockade of Ca2+ entry during diazoxide treatment by inhibiting the L-type Ca2+ channel with verapamil also completely reversed the beneficial effect of diazoxide during I/R. PKC-alpha was translocated to sarcolemma, whereas PKC-delta was translocated to the mitochondria and intercalated disc, and PKC-epsilon was translocated to the intercalated disc of the diazoxide pretreated hearts. Colocalization studies for mitochondrial distribution with tetramethylrhodamine ethyl ester (TMRE) and PKC isoforms by immunoconfocal microscopy revealed that PKC-delta antibody specifically stained the mitochondria. ATP was significantly increased in the diazoxide-treated hearts. Moreover, the data suggest that activation and translocation of PKC to mitochondria appear to be important for the protection mediated by mitoK(ATP) channel.