Department of Anesthesiology, Affiliated Hospital of Zunyi Medical University, 563000 Zunyi, China.
Department of Anesthesiology, Chengdu Fifth People's Hospital affiliated to Chengdu University of TCM, 610000 Chengdu, China.
Oxid Med Cell Longev. 2022 Mar 29;2022:7929784. doi: 10.1155/2022/7929784. eCollection 2022.
Our experiments were aimed at probing whether urocortin I postconditioning was beneficial for maintaining the mitochondrial respiratory function and inhibiting the surging of reactive oxygen species. In addition, our experiments also intended to reveal the relationships between urocortin I postconditioning and mitochondrial ATP-sensitive potassium channel.
Langendorff and MPA perfusion systems were used to establish myocardial ischemia-reperfusion injury model and cardiomyocytes hypoxia-reoxygenation injury model in rats, respectively. Isolated hearts and cardiomyocytes were randomly divided into normal group, ischemia-reperfusion/hypoxia-reoxygenation group, urocortin I postconditioning group, and 5-hydroxysolanoic acid (5-HD)+urocortin I group. At the end of balance (T) and reperfusion (T), cardiac functions, mitochondrial state3 respiratory, respiratory control ratio, mitochondrial respiratory enzyme activity, and mitochondrial cardiolipin content were measured. Our experiments also observed the ultrastructure of myocardium. The changes of cardiomyocyte mitochondrial permeability transition pore, mitochondrial membrane potential, reactive oxygen species, expression of apoptosis protein, and cardiomyocytes activity were detected at the end of reoxygenation.
The cardiac functions, mitochondrial respiratory function, and enzyme activity of the normal group were better than other three groups at T, and urocortin I postconditioning group was better than the IR group and 5-HD+urocortin I group. LVEDP, +dp/dt, mitochondrial respiratory function, and enzyme activity of IR group were worse than 5-HD+urocortin I group. Cardiolipin content of the normal group was higher than the other three groups at T, urocortin I postconditioning group was higher than the IR group and 5-HD+urocortin I group, and 5-HD+urocortin I group was still higher than the IR group. The ultrastructure of the normal group maintained the most integrated than the other groups, IR group suffered the most serious damage, and ultrastructure of the urocortin I postconditioning group was better than the IR group and 5-HD+urocortin I group. At the end of reoxygenation, activity of mitochondrial permeability transition pore and generation of reactive oxygen species of normal group were lower than the other groups, HR group and 5-HD+urocortin I group were higher than the urocortin I postconditioning group, and 5-HD+urocortin I group was still higher than the urocortin I postconditioning group. Normal group had the highest level of mitochondrial membrane potential at the end of reoxygenation, and the urocortin I postconditioning group was higher than the HR group and 5-HD+urocortin I group. The normal group had the lowest expression level of Bax and the highest expression level of Bcl-2 at the end of reoxygenation. Urocortin I postconditioning group had lower Bax expression but higher Bcl-2 expression than the HR and 5-HD+urocortin I group. Accordingly, the normal group had the highest activity of cardiomyocytes, and the urocortin I postconditioning group was higher than the HR group and 5-HD+urocortin I group.
Urocortin I postconditioning can protect the activity of cardiomyocytes after hypoxia-reoxygenation injury, improve the mitochondrial respiratory function, and enhance the contractility of isolated heart after myocardial ischemia-reperfusion injury. The alleviation of myocardial injury relates to the opening of mitochondrial ATP-sensitive potassium channel.
本实验旨在探讨加压素 UCNI 后处理对维持线粒体呼吸功能和抑制活性氧簇激增是否有益。此外，我们的实验还旨在揭示 UCNI 后处理与线粒体三磷酸腺苷敏感性钾通道之间的关系。
分别采用 Langendorff 和 MPA 灌注系统建立大鼠心肌缺血再灌注损伤模型和心肌细胞缺氧复氧损伤模型。分离的心脏和心肌细胞随机分为正常组、缺血再灌注/缺氧复氧组、UCNI 后处理组和 5-羟色氨（5-HD）+UCNI 组。在平衡（T）和再灌注（T）结束时，测量心功能、线粒体状态 3 呼吸、呼吸控制比、线粒体呼吸酶活性和线粒体心磷脂含量。我们的实验还观察了心肌的超微结构。在再复氧结束时检测心肌细胞线粒体通透性转换孔、线粒体膜电位、活性氧、凋亡蛋白表达和心肌细胞活性的变化。
在 T 时，正常组的心功能、线粒体呼吸功能和酶活性均优于其他三组，UCNI 后处理组优于 IR 组和 5-HD+UCNI 组。IR 组的 LVEDP、+dp/dt、线粒体呼吸功能和酶活性均较 5-HD+UCNI 组差。正常组的心磷脂含量在 T 时高于其他三组，UCNI 后处理组高于 IR 组和 5-HD+UCNI 组，5-HD+UCNI 组仍高于 IR 组。正常组的超微结构保持最完整，IR 组损伤最严重，UCNI 后处理组的超微结构优于 IR 组和 5-HD+UCNI 组。在再复氧结束时，正常组的线粒体通透性转换孔活性和活性氧生成较低，HR 组和 5-HD+UCNI 组较高，5-HD+UCNI 组仍高于 UCNI 后处理组。在再复氧结束时，正常组的线粒体膜电位最高，UCNI 后处理组高于 HR 组和 5-HD+UCNI 组。在再复氧结束时，正常组 Bax 的表达水平最低，Bcl-2 的表达水平最高。UCNI 后处理组 Bax 的表达水平低于 HR 组和 5-HD+UCNI 组，Bcl-2 的表达水平高于 HR 组和 5-HD+UCNI 组。因此，正常组的心肌细胞活性最高，UCNI 后处理组高于 HR 组和 5-HD+UCNI 组。
加压素 UCNI 后处理可减轻心肌细胞缺氧复氧损伤后的活性损伤，改善线粒体呼吸功能，增强心肌缺血再灌注损伤后心脏的收缩功能。心肌损伤的减轻与线粒体三磷酸腺苷敏感性钾通道的开放有关。
