大鼠骨骼肌中的线粒体效率：呼吸速率、底物和肌肉类型的影响。

Mitochondrial efficiency in rat skeletal muscle: influence of respiration rate, substrate and muscle type.

作者信息

Mogensen M, Sahlin K

机构信息

Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.

出版信息

Acta Physiol Scand. 2005 Nov;185(3):229-36. doi: 10.1111/j.1365-201X.2005.01488.x.

DOI:10.1111/j.1365-201X.2005.01488.x

PMID:16218928

Abstract

AIM

To investigate the hypothesis that mitochondrial efficiency (i.e. P/O ratio) is higher in type I than in type II fibres during submaximal rates of respiration.

METHODS

Mitochondria were isolated from rat soleus and extensor digitorum longus (EDL) muscles, representing type I and type II fibres, respectively. Mitochondrial efficiency (P/O ratio) was determined with pyruvate (Pyr) or palmitoyl-l-carnitine (PC) during submaximal (constant rate of adenosine diphosphate infusion) and maximal (V(max), state 3) rates of respiration and fitted to monoexponential functions.

RESULTS

There was no difference in V(max) between PC and Pyr in soleus but in EDL V(max) with PC was only 58% of that with Pyr. The activity of 3-hydroxyacyl-CoA dehydrogenase was threefold higher in soleus than in EDL. P/O ratio at V(max) was 8-9% lower with PC [2.33 +/- 0.02 (soleus) and 2.30 +/- 0.02 (EDL)] than with Pyr [2.52 +/- 0.03 (soleus) and 2.54 +/- 0.03 (EDL)] but not different between the two muscles (P > 0.05). P/O ratio was low at low rates of respiration and increased exponentially when the rate of respiration increased. The asymptotes of the curves were similar to P/O ratio at V(max). P/O ratio at submaximal respirations was not different between soleus and EDL neither with Pyr nor with PC.

CONCLUSION

Mitochondrial efficiency, as determined in vitro, was not significantly different in the two fibre types neither at V(max) nor at submaximal rates of respiration. The low V(max) for PC oxidation in EDL may relate to low activity of beta-oxidation.

摘要

目的

研究关于在次最大呼吸速率下I型纤维中线粒体效率（即磷氧比）高于II型纤维的假说。

方法

分别从大鼠比目鱼肌和趾长伸肌（EDL）中分离出线粒体，这两种肌肉分别代表I型和II型纤维。在次最大（恒定二磷酸腺苷输注速率）和最大（V(max)，状态3）呼吸速率下，用丙酮酸（Pyr）或棕榈酰-L-肉碱（PC）测定线粒体效率（磷氧比），并拟合为单指数函数。

结果

比目鱼肌中PC和Pyr的V(max)无差异，但在EDL中，PC的V(max)仅为Pyr的58%。比目鱼肌中3-羟酰基辅酶A脱氢酶的活性比EDL高两倍。在V(max)时，PC的磷氧比[2.33±0.02（比目鱼肌）和2.30±0.02（EDL）]比Pyr[2.52±0.03（比目鱼肌）和2.54±0.03（EDL）]低8 - 9%，但两种肌肉之间无差异（P>0.05）。在低呼吸速率下磷氧比低，当呼吸速率增加时呈指数增加。曲线的渐近线类似于V(max)时的磷氧比。在次最大呼吸时，比目鱼肌和EDL之间用Pyr或PC时的磷氧比均无差异。