Dulhunty A F
J Muscle Res Cell Motil. 1984 Jun;5(3):333-47. doi: 10.1007/BF00713111.
Average dimensions of transverse tubules were obtained from electron micrographs of thin sections of mammalian and amphibian skeletal muscle fibres and the effect of transverse tubule geometry on the electrical characteristics of the fibres has been considered. The preparations examined were toad sartorius, mouse soleus, rat extensor digitorum longus, soleus and sternomastoid muscles. The T-tubule dimensions varied considerably between the different preparations and the average volume to surface ratio of the transverse tubule in amphibian fibres (8.1 nm) was generally greater than that in mammalian fibres (3.0-6.2 nm). The small volume to surface ratio of the mammalian transverse tubule would tend to reduce the electrical space constant of the transverse tubule system and reduce the rate of cross-sectional activation of the fibres during a twitch contraction. The area of transverse tubule membrane in junctional contact with the sarcoplasmic reticulum was determined and was found to be greater in mammalian fibres than in amphibian fibres. The relative areas of junctional contact, along a unit length of transverse tubule, were the same in rat extensor digitorum longus and soleus fibres.
通过对哺乳动物和两栖动物骨骼肌纤维薄片的电子显微照片获取横小管的平均尺寸，并考虑了横小管几何形状对纤维电特性的影响。所检查的标本包括蟾蜍缝匠肌、小鼠比目鱼肌、大鼠趾长伸肌、比目鱼肌和胸锁乳突肌。不同标本之间的横小管尺寸差异很大，两栖动物纤维中横小管的平均体积与表面积之比（8.1纳米）通常大于哺乳动物纤维（3.0 - 6.2纳米）。哺乳动物横小管的小体积与表面积之比往往会降低横小管系统的电空间常数，并降低抽搐收缩期间纤维的横截面积激活率。测定了与肌浆网连接接触的横小管膜面积，发现其在哺乳动物纤维中比在两栖动物纤维中更大。在大鼠趾长伸肌和比目鱼肌纤维中，沿单位长度横小管的连接接触相对面积相同。
