Individuals with higher metabolic rates have lower levels of reactive oxygen species in vivo
Individuals with higher metabolic rates have lower levels of reactive oxygen species in vivo
复制标题
代谢率较高的个体体内活性氧水平较低
作者：
K. Salin;S. Auer;Agata M Rudolf;Graeme J. Anderson;Andrew G. Cairns;W. Mullen;R. Hartley;C. Selman;N. Metcalfe
能量代谢对氧化应激的影响越来越引起人们的兴趣，但氧消耗速率与活性氧（ROS）产生之间的关系却很模糊。线粒体中ROS（如过氧化氢，H2 O2）的产生主要是从体外测量间接推断的，这可能不能反映活体动物中实际的ROS产生。在这里，我们使用最近开发的MitoB探针测量体内H2 O2含量，该探针在活生物体的线粒体中浓缩，在那里它被H2 O2转化为称为MitoP的替代形式; MitoP/MitoB的比率指示体内线粒体H2 O2的水平。使用褐鳟鱼萨尔莫trutta，我们测试是否在体内过氧化氢含量超过24小时的时间内测量与个体间的标准代谢率（SMR）的变化。我们发现，H2 O2含量变化高达26倍，在相同的环境条件和营养状态下，相同年龄的鱼。H2 O2含量的个体间差异与线粒体密度无关，但与SMR显著相关：具有较高质量独立SMR的鱼H2 O2水平较低。SMR和体内H2 O2含量之间观察到的这种关系的机制需要进一步研究，但可能涉及线粒体解偶联，这可以同时增加SMR，但减少ROS的产生。据我们所知，这是第一项在生物体中进行的研究，表明具有较高耗氧率的个体实际上可以具有较低的H2 O2水平。
There is increasing interest in the effect of energy metabolism on oxidative stress, but much ambiguity over the relationship between the rate of oxygen consumption and the generation of reactive oxygen species (ROS). Production of ROS (such as hydrogen peroxide, H2O2) in the mitochondria is primarily inferred indirectly from measurements in vitro, which may not reflect actual ROS production in living animals. Here, we measured in vivo H2O2 content using the recently developed MitoB probe that becomes concentrated in the mitochondria of living organisms, where it is converted by H2O2 into an alternative form termed MitoP; the ratio of MitoP/MitoB indicates the level of mitochondrial H2O2 in vivo. Using the brown trout Salmo trutta, we tested whether this measurement of in vivo H2O2 content over a 24 h-period was related to interindividual variation in standard metabolic rate (SMR). We showed that the H2O2 content varied up to 26-fold among fish of the same age and under identical environmental conditions and nutritional states. Interindividual variation in H2O2 content was unrelated to mitochondrial density but was significantly associated with SMR: fish with a higher mass-independent SMR had a lower level of H2O2. The mechanism underlying this observed relationship between SMR and in vivo H2O2 content requires further investigation, but may implicate mitochondrial uncoupling which can simultaneously increase SMR but reduce ROS production. To our knowledge, this is the first study in living organisms to show that individuals with higher oxygen consumption rates can actually have lower levels of H2O2.