THE EFFECTS OF CORTISOL ON GLYCINE AND LEUCINE INCORPORATION IN VIVO AND IN VITRO IN STRIPS OF SKELETAL RAT MUSCLE

Abstract

ABSTRACT The in vivo incorporation of glycine-U-14C into the proteins of the adductor muscles of the hind limbs of rats under influence of cortisol was studied after intraperitoneal administration of the protein precursor. Intensive cortisol treatment resulted in a reduced amino acid incorporation. The in vitro incorporation of L-leucine-U-14C into the proteins of muscle strips prepared from the adductor muscles was stimulated by 38%, in rats previously treated with 1.0 mg cortisol per day during three days. In vitro addition of relatively low cortisol levels stimulated the in vitro incorporation of glycine-U-14C into the proteins of muscle strips by 14–30%. Higher hormonal concentrations reduced the incorporation to control levels. It was observed that under certain conditions cortisol treatment enhanced the incorporation of labelled precursors into the proteins of skeletal muscle, stimulating protein synthesis.