线粒体钙单向转运体参予肿瘤坏死因子α抗心肌缺血/复灌损伤的研究

MITOCHONDRIAL CALCIUM UNIPORTER PARTICIPATES IN TNF-ALPHA INDUCED CARDIOPROTECTION IN ISOLATED RAT HEARTS SUBJECTED TO ISCHEMIA/REPERFUSION

目的:探讨肿瘤坏死因子α(TNFα)诱导的抗心肌缺血/复灌损伤的保护作用是否与线粒体钙单向转运体以及相关成分有关。方法:采用离体大鼠心脏灌流方法,结扎冠状动脉左前降支30 min和复灌120 min复制局部缺血/复灌损伤模型,测定心肌梗死面积、冠脉流量和冠脉流出液中乳酸脱氢酶(LDH)含量。提取大鼠心肌线粒体,分光光度法测定520 nm吸光度。结果:与单纯缺血/复灌组相比,10 U/ml TNFα预处理明显降低心脏缺血/复灌后的梗死面积和复灌期冠脉流出液中LDH含量,促进冠脉流量的恢复;复灌开始用线粒体钙单向转运体激动剂精胺(20μmol/L)灌流10 min减弱了TNFα降低梗死面积和LDH含量的作用。10 U/ml TNFα预处理离体大鼠心脏后分离线粒体,520 nm处吸光度的下降明显低于对照组;精胺(50μmol/L)减弱了TNFα对520 nm处吸光度的影响。结论:TNFα诱导的抗心肌缺血/复灌损伤的保护作用可能与其抑制线粒体钙单向转运体的开放和抑制线粒体通透性转变孔道开放有关。

Aim： To investigate whether mitochondrial calcium uniporter participates in the cardioprotection of tumor necrosis factor a （TNFα） pretreatment in isolated rat hearts subjected to ischemia/reperfusion. Methods： Isolated perfused rat hearts were subjected to 30 min regional ischemia（occlusion of left anterior descending artery） and 120 rain reperfusion. The infarct size, coronary flow （CF） and lactate dehydrogenase（LDH） release during reperfusion were measured. The mitochondria of the heart were isolated and suspended in the swelling buffer for measurement of absorbance at 520 nm. Resalts：Pretreatment with TNFα at 10 U/ml for 7 min followed by 10 min washout reduced the infarct size and LDH release, and improved the recovery of CF during reperfusion. Administration of spermine（20 μmol/L）, an opener of mitochondrial calcium uniporter, for 10 min during early reperfusion attenuated the reduction of infarct size and LDH release, and improvement of CF induced by TNFα. In isolated mitochondria of the heart pretreated with TNFα, the absorbance at 520 nm decreased less than that of mitochondria without TNFα pretreatment. Administration of spermine（50 μmol/ L） attenuated the change of the absorbance induced by TNFα. Conclusion：The findings indicate that TNFα protects myocardium against ischemia/reperfusion injury via inhibiting mitochondrial calcium uniporter opening as well as mitochondrial permeability transition pore opening.