The direct actions of glucocorticoid hormones on protein turnover were studied in isolated soleus muscles. These steroids were found to decrease the rates of both protein synthesis and protein breakdown within 3 h and 4 h respectively. Synthetic steroids (e.g. dexamethasone) were found to be more potent than naturally secreted hormones (e.g. cortisol) in inducing these changes, but only at concentrations in vitro less than 10nm.
