Effects of Cortisone onin VitroIncorporation of Glycine Into Protein of Rat Diaphragm

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Abstract
Experiments were carried out in which effects of administration of cortisone in vivo on incorporation of the 14C label of glycine into skeletal muscle (diaphragm) protein was measured in vitro. Specific activity of glycine was measured both in cell water and in muscle protein and the amount of amino acid incorporated into protein was calculated. No significant difference was observed between the concentration of glycine in cell water of the cortisone-treated and that of the control diaphragms. The mean specific activities of glycine with respect to 14C in cell water were also similar, but the mean specific activity of glycine in protein was significantly diminished in the cortisone-treated group. Incorporation of glycine into total protein (expressed as jumole free glycine incorporated per Mmole protein glycine per hr) was also diminished in the cortisone-treated tissues. These experiments provide evidence against the hypothesis that cortisone acts by limiting access of amino acids into the cells, and in favor of the concept that the action of cortisone is to inhibit protein synthesis in skeletal muscle. (Endocrinology74: 709, 1964)