Changes in prostaglandin release associated with inhibition of muscle protein synthesis by dexamethasone.

Forelimb digit extensor muscles from fed rabbits were incubated in the absence or presence of dexamethasone (100 nM). The presence of dexamethasone decreased the rates of protein synthesis, prostaglandin F2 alpha and prostaglandin E2 release after a time lag of 2.5-3 h. Although intermittent stretching stimulated both protein synthesis and prostaglandin release in the presence of dexamethasone, the absolute activities of both processes were lower in the presence of the steroid than in its absence. It is suggested that the inhibitory action of dexamethasone on muscle protein synthesis in vitro results from its effect on the activity of plasma-membrane phospholipase A2.