van Ekeren G J, Sengers R C, Stadhouders A M
Department of Cell Biology and Histology, University of Nijmegen, The Netherlands.
Int J Exp Pathol. 1992 Feb;73(1):51-60.
In order to test the hypothesis that subsarcolemmal aggregation of skeletal muscle mitochondria, as noted in some patients with mitochondrial myopathies, is caused by an impaired oxygen supply to mitochondria, we exposed two groups of rats to 8% O2 during 44 or 45 days. One group performed mild exercise, as did a normoxic control group. After hypoxia we investigated fibre type composition, fibre diameter and capillarity of soleus and extensor digitorum longus (e.d.l.) muscles. Mitochondrial volume densities were determined by morphometric analysis. In both e.d.l. and soleus muscle fibre type composition was unchanged and fibre diameter was reduced after hypoxia. Capillary network was unchanged, hence capillary density was increased in both muscles after hypoxia (P less than 0.05 in untrained soleus). Total mitochondrial volume density was increased in soleus muscle, which was due to an increase in the volume density of intermyofibrillar mitochondria (P less than 0.05 in the trained group), whereas the volume density of subsarcolemmal mitochondria decreased. In e.d.l. muscle the volume density of both intermyofibrillar and subsarcolemmal mitochondria decreased. We conclude that subsarcolemmal aggregation of mitochondria did not occur after chronic hypoxia. In soleus and e.d.l. muscle, different changes in the volume densities of mitochondria occurred. This may be related to the relative amounts of type I and type II fibres within these muscles.
正如在一些线粒体肌病患者中所观察到的那样，骨骼肌线粒体在肌膜下聚集是由线粒体氧气供应受损所致，我们将两组大鼠在44或45天内暴露于8%的氧气环境中。其中一组进行轻度运动，常氧对照组也进行轻度运动。缺氧处理后，我们研究了比目鱼肌和趾长伸肌的纤维类型组成、纤维直径和毛细血管分布情况。通过形态计量分析确定线粒体体积密度。缺氧处理后，趾长伸肌和比目鱼肌的纤维类型组成均未改变，但纤维直径减小。毛细血管网络未发生变化，因此缺氧处理后两组肌肉的毛细血管密度均增加（未训练的比目鱼肌中P<0.05）。比目鱼肌的线粒体总体积密度增加，这是由于肌原纤维间线粒体的体积密度增加所致（训练组中P<0.05），而肌膜下线粒体的体积密度降低。在趾长伸肌中，肌原纤维间和肌膜下线粒体的体积密度均降低。我们得出结论，慢性缺氧后未出现线粒体在肌膜下聚集的情况。在比目鱼肌和趾长伸肌中，线粒体体积密度发生了不同的变化。这可能与这些肌肉中I型和II型纤维的相对含量有关。
