Interaction of sarcolemmal and mitochondrial ATP-sensitive K channel on cardioprotection

缺血预处理是一种现象，在这种现象中，短暂的间歇性缺血对随后的缺血性损伤具有矛盾的保护作用。为了表征肌层和线粒体ATP敏感K通道（KATP）对心脏保护的相互作用，我们研究了2,4-二硝基苯酚（一种使线粒体呼吸与ATP合成分离的质子载体）预处理对离体大鼠心室肌细胞黄蛋白氧化（线粒体解偶联指标）和肌层KATP激活的影响。研究了线粒体KATP抑制剂5-羟基癸酸对预处理效果的影响。本研究的主要发现是线粒体解偶联剂预处理使黄蛋白氧化和肌层KATP活化增敏。在5-羟基癸酸存在下，增敏作用完全消失。在没有代谢抑制的情况下，致敏心肌表现出几乎正常的黄蛋白氧化和肌醇活性。这些结果表明，如果我们假设一个记忆分子，记忆分子增强线粒体解偶联和肌层KATP的直接作用可以忽略不计，但面对代谢损伤，记忆分子增强线粒体解偶联和肌层KATP。此外，记忆分子的产生是5-羟基癸酸敏感的。接下来，我们评估了异氟醚对培养大鼠平滑肌细胞K_<ATP>通道活性的影响。K_<ATP>通道的开口是根据其特征的单通道电导（28±4pS）、100 μM pinacidil激活和3 μM格列本脲在细胞附着构型下的阻断来确定的。在细胞贴附记录过程中，将异氟烷应用于浴液可显著激活K_<ATP>通道。与细胞贴片相比，在外向膜片钳结构下，异氟醚没有诱导K_<ATP>通道电流的激活。异氟醚诱导的K_<ATP>通道激活被PKA抑制肽联合消除。结果表明，异氟醚通过PKA激活K_<ATP>通道电流，激活大鼠平滑肌细胞的K_<ATP>通道

Ischemic Preconditioning is a phenomenon in which brief intermittent periods of ischemia are paradoxically protective against subsequent ischemic injury. To characterize the interaction sarcolemmal and mitochondrial ATP-sensitive K channel (KATP) on cardioprotection, we studied pretreatment effects of 2,4-dinitrophenol, a protonophore that uncouples mitochondrial respiration from ATP synthesis, on both flavoprotein oxidation, an index of mitochondrial uncoupling and sarcolemmal KATP activation in isolated rat ventricular myocytes. Effects of 5-hydroxydecanoic acid, a mitochondrial KATP inhibitor, on the pretreatment effects were also studied. Major findings of this study were that pretreatment of mitochondrial uncoupler sensitizes flavoprotein oxidation and sarcolemmal KATP activation. In the presence of 5-hydroxydecanoic acid the sensitizing effects were completely abolished. Without metabolic inhibition, sensitized myocardium represents almost normal flavoprotein oxidation and sarcol … More emmal KATP activity. These results suggest that, if we assume a memory molecule, direct effects of the memory molecule potentiates mitochondrial uncoupling and sarcolemmal KATP are negligible, but the memory molecule potentates mitochondrial uncoupling and sarcolemmal KATP in the face of metabolic impairment. In addition, the production of the memory molecule is 5-hydroxydecanoic acid-sensitive.Next, we evaluated the effects of isoflurane on the K_<ATP> channel activities in cultured rat smooth muscle cells. Openings of K_<ATP> channels were identified on the basis of the characteristic single-channel conductance (28±4pS), activation by 100 μM pinacidil, and block by 3 μM glibenclamide in cell-attached configuration. Application of isoflurane to bath solution during cell-attached recording significantly activated K_<ATP> channels. In contrast to cell-attached patches, isoflurane did not induced activation on K_<ATP> channel currents in outside-out patchclamp configuration. Isoflurane induced activation of K_<ATP> channels was abolished by a combination of PKA inhibitor peptide. Our results indicated that isoflurane activated K_<ATP> channels in rat smooth muscle cells via PKA activation K_<ATP> channel currents Less