Department of Neurology, Tenth People's Hospital of Tongji University, Shanghai 200072, P.R. China.
Department of Geriatrics, Shanghai First People's Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200080, P.R. China.
Mol Med Rep. 2017 Dec;16(6):8289-8294. doi: 10.3892/mmr.2017.7644. Epub 2017 Sep 27.
Carbonic anhydrase III (CAIII) is expressed selectively in type I (slow‑twitch) myofibers. To investigate the association between changes in the expression of CAIII and skeletal muscle structure following denervation, the present study stained adjacent sections of skeletal muscle for ATPase and immunohistochemically for CAIII. In addition, differences in the protein expression and phosphatase activity of CAIII were examined by western blot and phosphatase staining between rat soleus and extensol digitorum longus (EDL) muscles, which are composed of predominantly slow‑ and fast‑twitch fibers, respectively. Upon denervation, the EDL muscle showed more pronounced structural changes, compared with the soleus muscle. There was a transformation from fast to slow fibers, and a concomitant increase in fibers positive for CAIII. Following denervation, the protein expression of CAIII initially increased and then decreased in the soleus muscle, whereas the protein expression of CAIII in the EDL muscle increased gradually with time. In contrast to the protein changes, phosphatase activity in the soleus and EDL muscles decreased significantly following denervation. These results indicated that, following denervation, changes in the expression of CAIII were associated with myofiber remodeling. Specifically, the change in the expression of CAIII reflected the conversion to type I myofibers, suggesting the importance of CAIII in resistance to fatigue in skeletal muscle.
碳酸酐酶 III（CAIII）选择性表达于 I 型（慢收缩）肌纤维。为了研究去神经支配后 CAIII 表达的变化与骨骼肌结构之间的关系，本研究对骨骼肌进行了 ATPase 染色和 CAIII 的免疫组织化学染色。此外，通过 Western blot 和磷酸酶染色，研究了 CAIII 的蛋白表达和磷酸酶活性在大鼠比目鱼肌和伸趾长肌（EDL）之间的差异，EDL 肌主要由快肌纤维组成，而比目鱼肌则主要由慢肌纤维组成。去神经支配后，EDL 肌比比目鱼肌表现出更明显的结构变化。出现了从快肌向慢肌的转变，同时 CAIII 阳性纤维也增加。去神经支配后，比目鱼肌中 CAIII 的蛋白表达先增加后减少，而 EDL 肌中 CAIII 的蛋白表达则随时间逐渐增加。与蛋白变化相反，去神经支配后比目鱼肌和 EDL 肌中的磷酸酶活性显著降低。这些结果表明，去神经支配后，CAIII 的表达变化与肌纤维重塑有关。具体而言，CAIII 表达的变化反映了向 I 型肌纤维的转化，提示 CAIII 在骨骼肌抗疲劳中的重要性。
