Effect of clenbuterol on skeletal muscle atrophy in mice induced by the glucocorticoid dexamethasone.

1. The ability of clenbuterol to antagonize the catabolic effect of the glucocorticoid dexamethasone on the skeletal muscles, soleus, gastrocnemius and extensor digitorum longus was studied in mice. 2. Daily injections of 5 mg dexamethasone/kg body weight over 10 days caused a significant (20%) loss of muscle weight and protein content in fast twitch but not in slow twitch muscles. 3. Inclusion of clenbuterol (4 mg/kg) in the diet for the period of dexamethasone treatment partly prevented glucocorticoid-induced muscle atrophy, and increasing the concentration of clenbuterol to 8 mg/kg diet totally prevented glucocorticoid-induced protein loss in all muscles.