Laboratoire des Hydrosystèmes Naturels et Anthropisés, UMR 5023 CNRS, Université de Lyon, ENTPE, Lyon, France.
Proc Biol Sci. 2019 Sep 25;286(1911):20191693. doi: 10.1098/rspb.2019.1693.
Metabolic activity sets the rates of individual resource uptake from the environment and resource allocations. For this reason, the relationship with body size has been heavily documented from ecosystems to cells. Until now, most of the studies used the fluxes of oxygen as a proxy of energy output without knowledge of the efficiency of biological systems to convert oxygen into ATP. The aim of this study was to examine the allometry of coupling efficiency (ATP/O) of skeletal muscle mitochondria isolated from 12 mammal species ranging from 6 g to 550 kg. Mitochondrial efficiencies were measured at different steady states of phosphorylation. The efficiencies increased sharply at higher metabolic rates. We have shown that body mass dependence of mitochondrial efficiency depends on metabolic intensity in skeletal muscles of mammals. Mitochondrial efficiency positively depends on body mass when mitochondria are close to the basal metabolic rate; however, the efficiency is independent of body mass at the maximum metabolic rate. As a result, it follows that large mammals exhibit a faster dynamic increase in ATP/O than small species when mitochondria shift from basal to maximal activities. Finally, the invariant value of maximal coupling efficiency across mammal species could partly explain why scaling exponent values are very close to 1 at maximal metabolic rates.
代谢活动设定了个体从环境中摄取资源的速率和资源分配。因此，从生态系统到细胞，生物体大小与代谢活动的关系已经得到了广泛的研究。直到现在，大多数研究都使用氧气通量作为能量输出的替代物，而没有了解生物系统将氧气转化为 ATP 的效率。本研究旨在检查从 6 克到 550 公斤的 12 种哺乳动物物种中分离出的骨骼肌线粒体的耦合效率（ATP/O）的异速关系。在不同的磷酸化稳态下测量线粒体效率。效率在较高的代谢率下急剧增加。我们已经表明，哺乳动物骨骼肌中线粒体效率对体质量的依赖性取决于代谢强度。当线粒体接近基础代谢率时，线粒体效率与体质量呈正相关；然而，在最大代谢率下，效率与体质量无关。因此，当线粒体从基础活动转变为最大活动时，大型哺乳动物的 ATP/O 比小型物种的动态增加更快。最后，最大耦合效率在哺乳动物物种中的不变值可以部分解释为什么在最大代谢率下，标度指数值非常接近 1。
