Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
J Cardiovasc Pharmacol. 2013 May;61(5):369-77. doi: 10.1097/FJC.0b013e318285f55b.
Cardiac mitochondria and the sarcolemmal (sarc)KATP channels contribute to cardioprotective signaling of anesthetic-induced preconditioning. Changes in mitochondrial bioenergetics influence the sarcolemmal ATP-sensitive K (sarcKATP) channel function, but whether this channel has impacts on mitochondria is uncertain. We used the mouse model with deleted pore-forming Kir6.2 subunit of sarcKATP channel (Kir6.2 KO) to investigate whether the functional sarcKATP channels are necessary for isoflurane activation of mitochondrial protective mechanisms. Ventricular cardiomyocytes were isolated from C57Bl6 wild-type (WT) and Kir6.2 KO mouse hearts. Flavoprotein autofluorescence, mitochondrial reactive oxygen species production, and mitochondrial membrane potential were monitored by laser-scanning confocal microscopy in intact cardiomyocytes. Cell survival was assessed using H2O2-induced stress. Isoflurane (0.5 mM) increased flavoprotein fluorescence to 180% ± 14% and 190% ± 15% and reactive oxygen species production to 118% ± 2% and 124% ± 6% of baseline in WT and Kir6.2 KO myocytes, respectively. Tetramethylrhodamine ethyl ester fluorescence decreased to 84% ± 6% in WT and to 86% ± 4% in Kir6.2 KO myocytes. This effect was abolished by 5HD. Pretreatment with isoflurane decreased the stress-induced cell death from 31% ± 1% to 21% ± 1% in WT and from 44% ± 2% to 35% ± 2% in Kir6.2 KO myocytes. In conclusion, Kir6.2 deletion increases the sensitivity of intact cardiomyocytes to oxidative stress, but does not alter the isoflurane-elicited protective mitochondrial mechanisms, suggesting independent roles for cardiac mitochondria and sarcKATP channels in anesthetic-induced preconditioning by isoflurane.
心肌线粒体和肌浆网（sar）KATP 通道有助于麻醉预处理的心脏保护信号转导。线粒体生物能学的变化影响肌浆网 ATP 敏感性 K（sarcKATP）通道的功能，但该通道是否对线粒体有影响尚不确定。我们使用肌浆网 sarcKATP 通道缺失孔形成 Kir6.2 亚基的小鼠模型（Kir6.2 KO），研究功能性 sarcKATP 通道是否是异氟烷激活线粒体保护机制所必需的。从 C57Bl6 野生型（WT）和 Kir6.2 KO 小鼠心脏分离心室肌细胞。通过激光扫描共聚焦显微镜在完整的心肌细胞中监测黄素蛋白自发荧光、线粒体活性氧的产生和线粒体膜电位。通过 H2O2 诱导的应激评估细胞存活率。异氟烷（0.5 mM）使 WT 和 Kir6.2 KO 心肌细胞的黄素蛋白荧光分别增加 180%±14%和 190%±15%，活性氧的产生分别增加 118%±2%和 124%±6%。四甲基罗丹明乙酯荧光分别降低至 WT 中的 84%±6%和 Kir6.2 KO 中的 86%±4%。该作用被 5HD 所消除。异氟烷预处理使 WT 心肌细胞应激诱导的细胞死亡从 31%±1%减少至 21%±1%，从 Kir6.2 KO 心肌细胞的 44%±2%减少至 35%±2%。总之，Kir6.2 缺失增加了完整心肌细胞对氧化应激的敏感性，但不改变异氟烷诱导的保护性线粒体机制，表明心肌线粒体和 sarcKATP 通道在异氟烷诱导的预处理中具有独立的作用。
