[Investigations on the utilisation of parenterally administered amino acids by premature and small-for-dates neonates. II. Investigations of elimination half life time, elimination constants, transfer and clearances of amino acids after short-time infusion of L-amino acid mixtures (author's transl)].

10 ml/kg body weight of a 5% standardized L-amino-acid-mixture was given within the first 25 days to 25 prematurely born infants of 32--37 weeks gestationale and 5 small-for-dates newborns. We studied the metabolic kinetics of these amino acids in the serum and calculated elimination half life time, elimination constants, clearance and transfer rates of the single amino acids. The results were correlated with sex, nutritional state and age. 5 additional experiments were performed with 3 prematurely born infants and 2 small-for-dates newborns. The following results were of special interests: 1. Nearly all amino-acids had half life times between 30 and 50 min. Ornithine and tryptophane were more (half life time: 70 and about 50 min, respectively) slowly eliminated, while arginine and glutamic acid had half life times of between 5 and 15 min. 2. There was no statistically significant differences between sexes. 3. Eutrophic prematures eliminated the amino acids much faster then the hypotrophic ones. 4. Hypotrophic premature infants showed slow elimination of nearly all amino acids compared with hypotrophic newborns. 5. The elimination of nearly all amino acids studied grew faster with increasing age. The most significant differences were registered between the 1st and 3rd weeks of life.