Recently, it is generally admitted that the infusion of amino acids and the administration of anabolic steroids are effective to prevent the protein catabolism after the surgical stress. But there are not so few unclear mechanism in the early amino acid metabolism in liver after the surgical stress.
Ten % of cristalline amino acids solution was injected intravenously to the adult male dog with average speed of 10ml/kg/hour for 60 minutes. Amino-nitrogen and urea nitrogen concentrations are measured at the sites of peripheral vein, hepatic vein for the period of six hours after the injection was initially given. These procedures are multiplily repeated in the following conditions—hemorrhagic hypotension, medication of corticoids, loading of ACTH, severance of autonomic nerves of liver, administration of anabolic steroids and so on.
According to the varying processes of fluctuated concentrations of above mentioned, the author finally obtained the following conclusions regarding the metabolism of amino acids in liver.
1. There is no marked difference between the infusion from peripheral vein and that from hepatic vein concerning the metabolic transaction of amino acids and urea production in liver. The metabolic function of amino acids in liver is comparatively great, however, it is found that the considerable amounts are converted to urea by the massive rapid infusion of amino acids.
2. The biological reactions become most active and promotive during the period of hemorrhagic hypotension. Moderate degree of hemorrhagic hypotension in this series is not induced to shock state. When the amino acids solution is infused within this period, the urea formation which is converted from these infused amino acids becomes more active. These phenomena have been revealed that the infused amino acids are rapidly catabolized in liver. Considering the slight increase of differenciated amino acids concentrations in hepatic and portal veins, and the rapid disappearance of infused amino acids from peripheral circulation, it is evident that the infused amino acids are satisfactory utilized for their anabolizations in liver.
3. The metabolic process of infused amino acids immediate after the hemorrhagic hypotension is entirely similar to those with ACTH and corticoids adiministrations under the same condition. It is thought that the change to transfer ability of amino acids after the addition of various stresses is proceeding strongly influenced with the increase of liberated corticosteroids.
4. The autonomic nerves of liver act inhibitorily in the intrahepatic metabolism of amino acids and urea formation to the stored and the infused amino acids, and control the homeostasis of protein metabolism in liver.
5. Protein anabolic steroids actively promote the protein synthesis of infused amino acids in liver, and clearly depress the increasing tendency of urea formation. These effects are evident even after the hemorrhagic hypotension.

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