[Changes in the cyclic AMP concentration in muscle in experimental dexamethasone myopathy]

A study was made of muscle cAMP content in rabbits with dexamethasone-induced myopathy. The experiments were performed in 15 male rabbits weighing 2.5--3.5 kg. Steroidal myopathy was produced by daily administration of 0.8 dexamethasone/kg body weight. Muscle biopsy was taken on experimental days 1, 3, 7 and 14. The content of cAMP was determined by radioimmunoassay. The clinical signs of myopathy occurred by day 7. The animals were immobilized day 14. The content of cAMP increased after the first administration of dexamethasone and remained unchanged till the end of the experiment. The increased cAMP content may be accounted for by dexamethasone effect on the enzymatic system that monitors the processes of cAMP activation and inhibition.