Amino Acid Mixtures Effective Parenterally for Long Continued Plasma Protein Production. Casein Digests Compared

Abstract

Our objective in the experiments tabulated below is a better understanding of the amino acid requirements for plasma protein production. It is important to determine the optimal make-up of mixtures which are used by the plasma-depleted dog to produce new plasma proteins. Briefly it may be said that the better mixtures of amino acids rate with the best food proteins in the production of new plasma protein in dogs standardized as described below under Methods. They are better tolerated when given intravenously than are casein digests, producing no clinical disturbance when given several times faster than the tolerable rate for such digests. They provide nitrogen balance as well as plasma protein production over periods of several months.In a previous report (11) it was found that good plasma protein regeneration was obtained from feeding or injecting the ten amino acids determined by Rose (21) to be essential for the growth of rats. Further tests have now been made of various mixtures of these ten acids and of non-essential amino acids. Similar mixtures of the ten essential amino acids plus glycine have appeared similarly well used and tolerated in the first trial in a human patient recently reported (2) as well as in other trials in patients to be reported soon. These mixtures appear not to have the undesirable vomiting and pyrogenic effects noted in an earlier report regarding the use in infants of an amino acid mixture containing more of the non-essential amino acids (25).Subcutaneous administration of the better mixtures of amino acids in 10 per cent solution in distilled water produces no clinical disturbance in dogs or in man and is accompanied by good utilization. The availability of the subcutaneous route is a great boon in many instances where repeated daffy injections are indicated. It is particularly fortunate that solutions of high concentration are so well tolerated.* We are indebted to Merck and Company, Inc., for the crystalline amino acids used in these experiments.We are indebted to Eli Lilly and Company for aid in conducting this work and for valuable materials. 6O7