Functional role of adrenergic receptor in skeletal muscle plasticity

我们调查了克伦特罗(Clenbuterol，每天1 mg/kg体重)是否能预防铸型制动(IMM)引起的骨骼肌纤维萎缩。将成年雄性SD大鼠分为对照组(CON)、CLE组、IMM组和IMM CLE组，维持9天。分离指长伸肌(EDL)和比目鱼肌(SOL)，ATPase染色后进行组织化学分析。IMM组EDL和SOL肌重均低于CON组。横截面积的定量分析显示，EDL肌萎缩仅限于II型纤维；SOL肌萎缩涉及I型和II型纤维。在IMM CLE组，IMM诱导的肌肉萎缩在EDL中得到缓解，但在SOL肌肉中没有。此外，在II型纤维中观察到了CLE的衰减作用。这些结果表明，CLE可减轻IMM引起的快抽动EDL肌中II型纤维的萎缩，但不能减轻慢抽动SOL肌中II型纤维的萎缩。

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.