Concentrations of Amino Acids in Plasma and Muscle

Abstract

CLINICAL and experimental evidence supports the hypothesis that androgenic steroid hormones are responsible for the acceleration of growth and muscular development that occurs during puberty. It has been shown that these compounds stimulate growth and nitrogen retention.¹This androgen-induced nitrogen retention is assumed to be due largely to an anabolic action on the protein of skeletal muscle. The mechanisms by which these hormones, or other factors, influence growth are not clear. Ultimately, any stimulus to growth must be reflected in the synthesis of new cellular proteins. The free amino acids from which these proteins are formed occur in two general pools, the extracellular pool which is mirrored by the plasma, and that of the cells. Increased growth might be associated with an increase of amino acids in all of these pools as well as in the proteins; with a decrease in both pools, reflecting a depletion of supplies of