Rajesh Katare Gopalrao, Sasaguri Shiro, Suzuki Ryoko, Maeda Hironori
Department of Surgery II, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi, Japan 783-8505.
Am J Physiol Heart Circ Physiol. 2003 Nov;285(5):H2171-8. doi: 10.1152/ajpheart.00143.2003. Epub 2003 Jun 19.
Reperfusion after a period of ischemia is associated with the formation of reactive oxygen species (ROS) and Ca2+ overload resulting in the opening of a nonspecific pore in the inner membrane of the mitochondria, called the mitochondrial permeability transition pore (PTP), leading to cell damage. Although endogenous antioxidants are activated because of oxidative stress following ischemia, their levels are not high enough to prevent reperfusion injury. Hence there is always a need for exogenous supplement of antioxidants, especially after acute ischemia. Here we demonstrated the effects of the antioxidant 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186) in preventing reperfusion injury of the heart by inhibition of PTP opening. Ischemia (30 min) by left coronary artery (LCA) occlusion and reperfusion (120 min) in Wistar rats after pretreatment with MCI-186 (10 mg/kg iv) infusion starting from 30 min before LCA occlusion resulted in 1) less area of myocardial infarction (19.2% vs. 61.6%), 2) well-maintained myocardial ATP content (P < 0.03 vs. control), 3) decreased mitochondrial swelling and reduced cytochrome c release, 4) increased expression of BCl-2, 5) lower prevalence of apoptotic cells (14.3% vs. 2.9%), and 6) reduced DNA fragmentation in the MCI-186-treated group. These cytoprotective effects of MCI-186 were inhibited on opening PTP before MCI-186 treatment with the PTP activators lonidamine (10 mg/kg iv) or atractyloside (5 mg/kg iv) but failed to inhibit the protective effects exerted by another antioxidant, allopurinol, suggesting that the PTP inhibiting property is specific for MCI-186. These results demonstrate that the radical scavenger MCI-186, by inhibiting the opening of the PTP, prevents necrosis and cytochrome c release and hence pathological apoptosis.
一段缺血期后的再灌注与活性氧（ROS）的形成及Ca2+超载相关，这会导致线粒体内膜上一个非特异性孔道——线粒体通透性转换孔（PTP）开放，进而引起细胞损伤。尽管内源性抗氧化剂会因缺血后的氧化应激而被激活，但其水平不足以预防再灌注损伤。因此，一直需要外源性补充抗氧化剂，尤其是在急性缺血后。在此，我们证明了抗氧化剂3-甲基-1-苯基-2-吡唑啉-5-酮（MCI-186）通过抑制PTP开放来预防心脏再灌注损伤的作用。在Wistar大鼠中，从左冠状动脉（LCA）闭塞前30分钟开始静脉输注MCI-186（10 mg/kg）进行预处理，然后进行LCA闭塞30分钟及再灌注120分钟，结果显示：1）心肌梗死面积减小（19.2%对61.6%）；2）心肌ATP含量维持良好（与对照组相比P < 0.03）；3）线粒体肿胀减轻，细胞色素c释放减少；4）BCl-2表达增加；5）凋亡细胞发生率降低（14.3%对2.9%）；6）MCI-186治疗组的DNA片段化减少。在用PTP激活剂氯尼达明（10 mg/kg静脉注射）或苍术苷（5 mg/kg静脉注射）在MCI-186治疗前开放PTP时，MCI-186的这些细胞保护作用受到抑制，但未能抑制另一种抗氧化剂别嘌呤醇发挥的保护作用，这表明PTP抑制特性对MCI-186具有特异性。这些结果表明，自由基清除剂MCI-186通过抑制PTP开放，可预防坏死和细胞色素c释放，从而防止病理性凋亡。
