Effect of serum from chickens treated with clenbuterol on myosin accumulation, beta-adrenergic receptor population, and cyclic AMP synthesis in embryonic chicken skeletal muscle cell cultures.

Broiler chickens at 35 d of age were fed 1 ppm clenbuterol for 14 d. This level of dietary clenbuterol led to 5-7% increases in the weights of leg and breast muscle tissue. At the end of the 14-d period, serum was prepared from both control and clenbuterol-treated chickens, and was then employed as a component of cell culture media at a final concentration of 20% (v/v).