琥珀酸在心肌缺血过程中积累,并在再灌注过程中迅速氧化,通过从线粒体复合物II到复合物I的反向电子转移(RET)导致活性氧(ROS)产生,有利于细胞死亡。鉴于连接蛋白43(Cx43)调节线粒体ROS的产生,我们使用诱导型敲除Cx43Cre-ER(T)/fl小鼠研究了Cx43是否影响RET。耗氧量,ROS生产,在肌膜下分析了膜电位和辅酶Q(CoQ)池(SSM,表达Cx43)和从野生型Cx43fl/fl小鼠和用4-羟基他莫昔芬(4OHT)治疗的Cx43Cre-ER(T)/fl敲除动物分离的纤维间(IFM)心脏线粒体。此外,在接受缺血再灌注(IR)的这些动物的离体心脏中评估梗死面积,无论是否用丙二酸治疗,复合物II抑制剂减弱RET。在SSM中,琥珀酸依赖性ROS产生和RET显著降低,但不是IFM,来自缺乏Cx43的动物。线粒体膜电位,RET司机,群体之间是相似的,而CoQ池(2.165±0.338vs.4.18±0.55nmol/mg蛋白质,p<0.05),其还原状态在Cx43缺陷动物中明显较低。与Cx43fl/fl相比,用4OHT治疗的Cx43Cre-ER(T)/fl小鼠的离体心脏在IR后的梗死面积较小,尽管在缺血末期琥珀酸浓度相似,没有丙二酸盐的额外保护。Cx43缺乏减弱SSM中RET产生的ROS,但不是IFM,并与CoQ水平的降低和其氧化还原状态的变化有关。这些结果可能部分解释了在这些动物中观察到的梗死面积减少及其缺乏丙二酸保护作用。
Succinate accumulates during myocardial ischemia and is rapidly oxidized during reperfusion, leading to reactive oxygen species (ROS) production through reverse electron transfer (RET) from mitochondrial complex II to complex I, and favoring cell death. Given that connexin 43 (Cx43) modulates mitochondrial ROS production, we investigated whether Cx43 influences RET using inducible knock-out Cx43Cre-ER(T)/fl mice. Oxygen consumption, ROS production, membrane potential and coenzyme Q (CoQ) pool were analyzed in subsarcolemmal (SSM, expressing Cx43) and interfibrillar (IFM) cardiac mitochondria isolated from wild-type Cx43fl/fl mice and Cx43Cre-ER(T)/fl knock-out animals treated with 4-hydroxytamoxifen (4OHT). In addition, infarct size was assessed in isolated hearts from these animals submitted to ischemia-reperfusion (IR), and treated or not with malonate, a complex II inhibitor attenuating RET. Succinate-dependent ROS production and RET were significantly lower in SSM, but not IFM, from Cx43-deficient animals. Mitochondrial membrane potential, a RET driver, was similar between groups, whereas CoQ pool (2.165 ± 0.338 vs. 4.18 ± 0.55 nmol/mg protein, p < 0.05) and its reduction state were significantly lower in Cx43-deficient animals. Isolated hearts from Cx43Cre-ER(T)/fl mice treated with 4OHT had a smaller infarct size after IR compared to Cx43fl/fl, despite similar concentration of succinate at the end of ischemia, and no additional protection by malonate. Cx43 deficiency attenuates ROS production by RET in SSM, but not IFM, and was associated with a decrease in CoQ levels and a change in its redox state. These results may partially explain the reduced infarct size observed in these animals and their lack of protection by malonate.