Start Of Perfusion Research Articles

Uptake and metabolism of amino acids by the dog liver perfused in situ

Dog livers were perfused in situ for periods up to 6 hr with dog blood recycled through a pump-oxygenator. An amino acid mixture was administered for 90 min. Concentrations of amino acids were determined at intervals of 30 min or more. Rates of uptake and metabolism were calculated. After the start of perfusion, there is a fall in most plasma amino acid concentrations and a reciprocal rise in liver amino acids. Addition of amino acids causes a sharp rise in plasma amino acids. There is a rapid uptake of most of the amino acids by liver, although the concentrations of amino acids in liver fail to rise appreciably. Notable exceptions are valine, leucine, and isoleucine. Uptake of amino acids stimulates: a) an increase in the rate of synthesis of urea which ultimately accounts for 90% of the metabolized amino acids; b) a net synthesis of ornithine; and c) net noncatabolic metabolism of amino acids which may in part be protein synthesis. The results support the view that the liver temporarily stores a part of ingested amino acids as proteins, and subsequently makes them available to other organs.

ピラジナミドの定量法 (第4報)

Decomposition of pyrazinamide in the digestive tract and the liver was examined and it was found that although this compound is stable in artificial gastric and enteric solutions, a part of it was decomposed to pyrazinoic acid by the enzyme solution of rabbit enteric membrane, acetone-dried powder of bovine enteric membrane, and homogenate of a rabbit liver. Perfusion experiments were conducted with excised liver of a rabbit and the concentration of pyrazinamide and pyrazinoic acid in the perfusion solution was determined at definite intervals by colorimetry. It was thereby found that a fair amount of pyrazinamide (ca. 100γ/cc.) was decomposed 5 minutes after the start of perfusion and that it changed almost completely into pyrazinoic acid by two hours of perfusion.