Department of Biological Sciences, Brock University, St. Catharines, ON, Canada L2S 3A1.
Comp Biochem Physiol A Mol Integr Physiol. 2012 Jul;162(3):157-62. doi: 10.1016/j.cbpa.2012.01.022. Epub 2012 Feb 21.
Within mammalian species, standard metabolic rate (SMR) increases disproportionately with body mass (Mb), such that the mass-specific SMR correlates negatively with Mb. This phenomenon can be explained in part by reduced cellular metabolic rates in larger species. To better understand the cause(s) of this cellular metabolic rate allometry we have used an ex vivo approach to isolate and identify potential contributors. Skeletal myoblasts from mammalian species ranging inMb from 30 g to over 300,000 g were isolated and differentiated into myotubes in vitro. Oxygen consumption rates, citrate synthase (CS) activity, and lactate dehydrogenase (LDH) activity were measured in myotubes under standardized conditions. No correlation of any of these parameters was observedwith speciesMb, suggesting that there is no genetic contribution to between-species differences in cellular metabolic rates. Myotubes were incubated in serum from species ranging from 30 g to 400,000 g to determine whether between-species differences in the levels of metabolically important hormones might produce allometric trends in the cultured cells. However, there was no observed effect of serum donor Mb on any of the metabolic characteristicsmeasured. Thus, there is no evidence for a relationship between skeletal muscle oxidative metabolism and Mb in an ex vivo model.
在哺乳动物物种中，标准代谢率（SMR）与体重（Mb）不成比例地增加，使得比特定的 SMR 与 Mb 呈负相关。这种现象可以部分解释为较大物种的细胞代谢率降低。为了更好地理解这种细胞代谢率的分形学原因，我们使用了一种离体方法来分离和鉴定潜在的贡献者。从 Mb 范围在 30 克到 300,000 克以上的哺乳动物物种中分离出骨骼肌成肌细胞，并在体外分化为肌管。在标准化条件下测量肌管中的耗氧量、柠檬酸合酶（CS）活性和乳酸脱氢酶（LDH）活性。这些参数中没有任何一个与物种 Mb 相关，这表明细胞代谢率的种间差异没有遗传贡献。将肌管在来自 30 克到 400,000 克的物种的血清中孵育，以确定代谢重要激素的种间差异是否会在培养细胞中产生分形趋势。然而，血清供体 Mb 对测量的任何代谢特征都没有观察到影响。因此，在离体模型中，没有证据表明骨骼肌氧化代谢与 Mb 之间存在关系。
