Concentration of Amino-acids in Rat Muscle and Plasma

Abstract

NEITHER the precise mechanism of amino-acid transport in muscle nor the means of its regulation is known. In most instances (there are exceptions^1,2) what has been examined is the ratio of radioactivity in the tissue water to that in the medium after incubating muscle with a single radioactive amino-acid. There is no assurance that this accurately reflects the concentration ratio for the unlabelled amino-acid. Moreover, these experiments are of the nature of black-box investigations since the concentration of individual amino-acids in rat diaphragm and heart muscle, the two tissues most frequently used for in vitro examination, has only infrequently been reported³. Clearly, what is required of a proper examination of the mechanism, and the hormonal regulation, of amino-acid penetration into muscle is a chemical determination of the exact amount of amino-acids in tissue and medium. Preparatory to such an investigation we have determined the concentration of ninhydrin reacting material in rat diaphragm and heart muscle and in rat plasma.