Urinary excretion of alpha-amino nitrogen following intravenous administration of amino acid mixtures.

It has recently been reported (Howe, Unna, Richards, and Seeler (1)) that an amino acid mixture consisting largely of the essential amino acids in their natural form can be administered to dogs intravenously without gross ill effect at much faster rates than can a similar mixture which contains a larger proportion of racemic amino acids. Since the rapid administration of amino acids might result in their increased loss in the urine, as suggested by Elman and Weiner (2), experiments were undertaken to determine whether the practical advantages offered by an increase in the rate of infusion might be offset by a greater loss of amino acids in the urine. Studies were also carried out on the relation of the urinary excretion of a-amino nitrogen both to the type of amino acid preparation infused and to the state of protein depletion of the animal. The rate of removal from the circulation was determined by measurement of the plasma amino acid levels, and urines were analyzed for the ten essential amino acids by the procedure of Stokes, Gunness, Dwyer, and CaswelP (3).