The Relative Efficiency of Different forms of Intravenously Administered Nitrogen on Nitrogen Balance and Amino Acid Excretion

Abstract

An enzymic casein hydrolysate and two mixtures of crystalline amino acids have been compared for their ability to promote nitrogen retention in protein depleted dogs when given intravenously at varying levels of nitrogen intake. At levels just sufficient to establish nitrogen equilibrium the mixture of ten essential amino acids and glycine (V_u) was slightly more effective in promoting nitrogen retention than the other two substances. At higher levels of intake the hydrolysate was considerably more effective than the V_u mixture. Urinary excretion of amino acid nitrogen was always greater with the crystalline mixtures than with the hydrolysate. Conversely, more peptide nitrogen appeared in the urine when the hydrolysate was given. The sums of nitrogen lost in both forms were approximately equal although the crystalline mixture was given more slowly than the hydrolysate in order to avoid emesis.