RNA polymerase and ribonuclease activities in skeletal muscle of prednisolone-treated rats.

Nuclei isolated from gastrocnemius muscles of rats given prednisolone acetate i.p. showed decreased levels of Mg2ł-dependent RNA polymerase activity while the Mn2+-dependent polymerase activity showed no significant change from control levels. Both acid and alkaline ribonuclease activities in gastrocnemius and liver of prednisolone-treated rats were lower than levels in untreated rats. Although evidence was obtained for the existence of an inhibitor of ribonuclease activity in skeletal muscle, the effect of the glucocorticoid on ribonuclease activity was not due to increased levels of any such inhibitor.