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

缺血预处理是一种现象，其中短暂的间歇性缺血期对随后的缺血性损伤具有矛盾的保护作用。为了表征肌膜和线粒体 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（一种将线粒体呼吸与 ATP 合成解偶联的质子载体）对离体大鼠心室肌细胞中黄素蛋白氧化（线粒体解偶联指数）和肌膜 KATP 激活的预处理作用。还研究了线粒体 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的预处理使黄素蛋白氧化和肌膜 KATP 激活变得敏感。在 5-羟基癸酸存在下，敏化作用被完全消除。如果没有代谢抑制，致敏心肌几乎呈现正常的黄素蛋白氧化和肌醇 KATP 活性。这些结果表明，如果我们假设记忆分子，则记忆分子增强线粒体解偶联和肌膜 KATP 的直接作用可以忽略不计，但在面对代谢损伤时，记忆分子增强线粒体解偶联和肌膜 KATP。此外，记忆分子的产生对5-羟基癸酸敏感。 接下来，我们评估了异氟烷对培养的大鼠平滑肌细胞中K_<ATP>通道活性的影响。 K_<ATP> 通道的开放基于特征性单通道电导 (28±4pS)、100 μM 吡那地尔激活和细胞贴壁配置中 3 μM 格列本脲阻断来识别。在细胞贴壁记录过程中，将异氟烷应用于浴液中可显着激活 K_<ATP> 通道。与细胞贴附的膜片相比，异氟烷在外向膜片钳配置中不会诱导 K_<ATP> 通道电流的激活。异氟烷诱导的K_<ATP>通道的激活被PKA抑制肽的组合消除。我们的结果表明，异氟烷通过 PKA 激活 K_<ATP> 通道电流激活大鼠平滑肌细胞中的 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