Oka Norihiko, Wang Lixing, Mi Wenyu, Zhu Wei, Honjo Osami, Caldarone Christopher A
Division of Cardiovascular Surgery, the Hospital for Sick Children, University of Toronto, Ontario, Canada.
J Thorac Cardiovasc Surg. 2008 Jan;135(1):123-30, 130.e1-2. doi: 10.1016/j.jtcvs.2007.05.009.
Mitochondrial permeability transition pore opening plays a critical role in mediating the mitochondrial response to ischemia/reperfusion injury and initiation of apoptosis. We tested whether inhibition of mitochondrial permeability transition pore opening with cyclosporine A prevented apoptosis-related alterations in mitochondrial structure and function after cardioplegic arrest.
Newborn piglets (age approximately 14 days) underwent cardiopulmonary bypass, cardioplegic arrest (60 minutes), weaning from bypass, and 6-hour reperfusion. Comparison was made among cold crystalloid cardioplegia (n = 5), cold crystalloid cardioplegia with cyclosporine A pretreatment (n = 5), and noncardiopulmonary bypass (n = 5) groups.
Early apoptosis signaling events (Bax translocation to the mitochondria) were prominent in cold crystalloid cardioplegia and prevented in cold crystalloid cardioplegia + cyclosporine A myocardium. Mitochondrial release of cytochrome c, determined by Western blot of cytosolic fractions and confocal quantitative colocalization analysis, was also prominent in cold crystalloid cardioplegia but prevented in cold crystalloid cardioplegia + cyclosporine A myocardium. Electron microscopy of isolated mitochondria demonstrated subjective alterations in mitochondrial architecture in cold crystalloid cardioplegia mitochondria, which were prevented by cyclosporine A. Deficiency of isolated mitochondrial oxygen consumption at Complex I was present in cold crystalloid cardioplegia mitochondria and prevented by cyclosporine A (P < .01). The frequency of deoxyuride-5'-triphosphate biotin nick end labeling-positive myocytes was diminished in cold crystalloid cardioplegia + cyclosporine A myocardium (P < .05). Mitochondrial resistance to calcium-mediated mitochondrial permeability transition pore opening was not different in cold crystalloid cardioplegia and noncardiopulmonary bypass mitochondria, suggesting that calcium overload is not solely responsible for the observed deficits in mitochondrial function.
Cyclosporine A pretreatment prevents postcardioplegia alterations in mitochondrial structure and function in a clinically relevant model of neonatal cardiac surgery. Prevention of mitochondrial permeability transition pore opening and apoptosis signaling events (Bax translocation and mitochondrial permeabilization) are associated with superior mitochondrial preservation.
线粒体通透性转换孔开放在介导线粒体对缺血/再灌注损伤的反应及凋亡启动过程中起关键作用。我们测试了用环孢素A抑制线粒体通透性转换孔开放是否能预防心脏停搏后线粒体结构和功能的凋亡相关改变。
新生仔猪（约14日龄）接受体外循环、心脏停搏（60分钟）、脱离体外循环及6小时再灌注。对冷晶体心脏停搏组（n = 5）、冷晶体心脏停搏+环孢素A预处理组（n = 5）和非体外循环组（n = 5）进行比较。
早期凋亡信号事件（Bax转位至线粒体）在冷晶体心脏停搏组中显著，而在冷晶体心脏停搏+环孢素A的心肌中被预防。通过胞质组分的蛋白质印迹法和共聚焦定量共定位分析确定的细胞色素c的线粒体释放，在冷晶体心脏停搏组中也很显著，但在冷晶体心脏停搏+环孢素A的心肌中被预防。分离线粒体的电子显微镜检查显示冷晶体心脏停搏线粒体的线粒体结构有主观改变，而环孢素A可预防这种改变。冷晶体心脏停搏线粒体中复合体I处分离线粒体氧消耗不足，而环孢素A可预防（P <.01）。冷晶体心脏停搏+环孢素A的心肌中脱氧尿苷-5'-三磷酸生物素缺口末端标记阳性心肌细胞的频率降低（P <.05）。冷晶体心脏停搏和非体外循环线粒体对钙介导的线粒体通透性转换孔开放的抵抗力无差异，提示钙超载并非观察到的线粒体功能缺陷的唯一原因。
在新生儿心脏手术的临床相关模型中，环孢素A预处理可预防心脏停搏后线粒体结构和功能的改变。预防线粒体通透性转换孔开放和凋亡信号事件（Bax转位和线粒体通透性改变）与更好的线粒体保存相关。
