Cartwright J, Goldstein M A
J Mol Cell Cardiol. 1985 Jan;17(1):1-7. doi: 10.1016/s0022-2828(85)80087-0.
In the postnatal rat heart, muscle cells continue to divide as well as increase in size. At the same time the cells in the soleus muscle (a slow skeletal muscle) do not divide, although they continue to grow in size. Since microtubules may have a role in orienting intracellular structures in muscle, we determined the numbers of microtubules/micron2 cross-sectional area in the rat heart papillary muscle during development. We have previously determined that in the soleus muscle, microtubule number/micron2 increases to a maximum at five to nine days of age, after which there is an abrupt decrease to a steady level characteristic of the adult [2]. The numbers of microtubules/micron2 in the heart were similar to those in the soleus muscle at the same age. The numbers of microtubules/micron2 increased from birth to a maximum at nine days, then decreased to a steady state. This decrease in microtubule number in heart muscle occurred at 9 to 11 days as in the soleus muscle. The distributions of microtubules are thus similar for cardiac and slow skeletal muscle, suggesting similar function(s) in these different muscle types.
在出生后的大鼠心脏中，肌细胞持续分裂并增大体积。与此同时，比目鱼肌（一种慢肌骨骼肌）中的细胞不分裂，尽管它们的体积持续增大。由于微管可能在肌肉细胞内结构的定向中发挥作用，我们测定了发育过程中大鼠心脏乳头肌每平方微米横截面积内的微管数量。我们之前已经确定，在比目鱼肌中，每平方微米的微管数量在5至9日龄时增加到最大值，之后急剧下降至成年期特有的稳定水平[2]。心脏中每平方微米的微管数量与同年龄比目鱼肌中的相似。每平方微米的微管数量从出生到9日龄时增加到最大值，然后下降至稳定状态。心肌中微管数量的减少与比目鱼肌一样发生在9至11日龄。因此，心脏和慢骨骼肌中微管的分布相似，表明这些不同肌肉类型具有相似的功能。
