Effects of Cortisol on Amino Acids in Skeletal Muscle and Plasma

Abstract

Effects of cortisol administration on concentrations of free amino acids and other ninhydrin reacting substances (NRS) were determined in plasma of fasted mice and skeletal muscle of fasted and nonfasted mice by column chromatography. The following amino acids were found: alanine, arginine, aspartic acid, glutamic acid, glycine, glutamine, histidine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, tryptophan and valine. Cystine and cysteine were absent and traces of phenylalanine and tyrosine were present. Non-amino acid NRS found included carnosine, glycerophosphoethanolamine, phosphoethanolamine, phosphoserine, taurine and urea. Taurine accounted for more than half the total NRS. Administration of cortisol appeared to result in increased concentration of virtually all amino acids and urea in both fasted and nonfasted animals. In the fed group, the difference between the sums of amino acids present was significant. Cortisol injection also increased plasma amino acids but to a lesser degree than in muscle. The findings are not consistent with the hypothesis that cortisol affects protein metabolism in muscle by limiting access of amino acids into the cells.