Free amino acid and amine concentrations in liver: effects of hydrocortisone and fasting

Abstract

Concentrations of the following Ninhydrin-reacting substances (NRS) were determined in the unhydrolyzed protein-free fraction of mouse liver by column chromatography: phosphoethanolamine, taurine, urea, aspartic acid, threonine, serine, glutamine, proline, glutamic acid, glycine, alanine, valine, cystine, methionine, isoleucine, leucine, tyrosine, phenylalanine, ß-alanine, ß-aminoisobutyric acid, α-aminobutyric acid, ornithine, ethanolamine, lysine, histidine, and arginine. The NRS present in highest concentration was taurine. Adrenalectomy, fasting for 24 hr, and cortisol administration had little effect on the sum of NRS or individual amino acids. Administration of cortisol did, however, decrease the concentration of amino acids in fasted adrenalectomized animals but increased their concentration in nonfasted adrenalectomized animals. Since the concentration of amino acids was lowered or raised under circumstances known to increase protein synthesis, it is concluded that increased protein synthesis promoted by cortisol is independent of the total pool of amino acids in liver.