Clenbuterol, a beta 2-agonist, retards atrophy in denervated muscles.

Denervated soleus, anterior tibialis, and gastrocnemius muscles, but not the extensor digitorum longus, contained 95-110% more protein after 2-3 wk of treatment with the adrenergic beta 2-receptor agonist, clenbuterol, than denervated controls. In addition, the twofold difference in the protein content of denervated solei was paralleled by similar changes in contractile strength and muscle fiber cross-sectional area. In contrast, when the innervated contralateral muscles were examined, the extensor digitorum longus and anterior tibialis showed relatively small increases in protein of 32 and 19%, respectively, whereas the soleus and gastrocnemius were unaffected. The magnitude of the effects of clenbuterol in sparing the mass and functional capacity of denervated muscle suggests that this agent may be important in studies of neuromuscular diseases and disuse atrophy.