Abstract
1. Experiments were designed to be carried out with dog's intestine to study amino acid absorption. Similar experiments were designed to study the fate of amino acids after administration of 14C-labelled amino acids to rats. Results of experiments are follows: Two thirds of amino acids, disappeared from the intestinal lumen in 30 minutes after administration, were found to be retained in the wall of intestine, mainly as a bound form, i. e. protein. The remaining amount, 1/3 of the amino acid absorbed from the intestinal lumen, appeared in the portal blood. One half or two thirds of the amino acids absorbed in the portal blood are retained in liver to be utilized for protein synthesis or for other physiological need. The remaining of the amino acid not retained and passed through the liver are utilized in the other tissues. Thus the amino acid taken in the total circulating blood is only one thirds- or one nineth of the amino acids absorbed from the intestinal lumen in 30 minutes after administratron. The amino acid thus retained in the intestinal wall and liver was found to be transported by the blood in a bound form, probably in a form of protein to various tissues in the body. Thus the protein which bounds the absorbed amino acids in the intestinal wall and liver seems to play a role as a functional reserve protein.
2. Nutritional efficiency of amino acid mixture of various composition was examined with the human subjects by measuring the amino acid concentration in serum after administration of various kinds of amino acid mixture. The results were confirmed with rats by measuring the growth curve, protein efficiency ratio and net protein utilization. Experimental results revealed that the utilization efficiency is the best with the amino acid mixture which contains the same amounts of the non essential amino acid with that of the essential amino acids of FAO pattern. The E/T ratio of the mixture is about 4.0.
