Functional role of adrenergic receptor in skeletal muscle plasticity

我们研究了每日服用克仑特罗（CLE; 1 mg/kg BW/天）是否可以预防固定制动（IMM）引起的骨骼肌纤维萎缩。将成年雄性Sprague-Dawley大鼠分配到对照（CON）、CLE、IMM和IMM+CLE组，并维持9天。分离趾长伸肌（EDL）和比目鱼肌（SOL），ATP酶染色后进行组织化学分析。IMM组的趾长肌和SOL肌重量低于CON组。横截面积的定量分析显示，EDL肌肉萎缩仅限于II型纤维; SOL肌肉萎缩涉及I型和II型纤维。在IMM+CLE组中，IMM诱导的肌肉萎缩在EDL中减弱，但在SOL肌肉中未减弱。此外，CLE在II型纤维中观察到衰减效果。这些结果表明，CLE衰减IMM诱导的II型纤维的萎缩，在快收缩的EDL肌肉，但不是在慢收缩的SOL肌肉。

We investigated whether daily administration of clenbuterol(CLE;1mg/kg BW per day) prevented casted-immobilization(IMM)-induced atrophy of skeleta muscle fibers. Adult male Sprague-Dawley rats were assigned to control(CON), CLE, IMM, and IMM+CLE groups, and were maintained for 9 days. The extensor digitorum longus(EDL) and soleus(SOL) muscles were isolated and analyzed histochemically after ATPase staining. EDL and SOL muscle weights in the IMM group were lower than those in the CON group. Quantitative analysis of cross-sectional areas revealed that EDL muscle atrophy was limited to type II fibers; SOL muscle atrophy involved type I and type II fibers. In the IMM+CLE group, IMM-induced muscle atrophy was attenuated in the EDL, but not in the SOL muscle. Moreover, the attenuating effect of CLE was observed in type II fibers. These results suggest that CLE attenuated IMM-induced atrophy of type II fibers in the fast-twitch EDL muscle but not in the slow-twitch SOL muscle.