INFLUENCE OF AMINO-ACID CONCENTRATION IN THE CULTURE-MEDIUM ON THE RATE OF AMINO-ACID-INCORPORATION INTO PROTEIN AND AMINO-ACID OXIDATION OF CULTURED CHICKEN HEPATOCYTES

Hepatocytes from a 70-d-old male broiler were dissociated using a modified technique of double perfusion with an isotonic solution through the jejunum mesenteric and pancreatic veins followed by collagenase perfusion. A basal medium was made up with the same amino-acid composition of the whole chicken egg, diluted 25 times. Dilutions of 1:1, 1:2, 1:4, 1:20, 1:40 and 1:80 of the basal medium constituted the experimental treatments. Amino-acid incorporation into protein and amino-acid oxidation were determined by counting the radioactivity of [H-3]-leucine present in cellular proteins and the (CO2)-C-14 released by the cells for 6 periods of time. The rate of amino-acid incorporation into cellular proteins was proportional to the concentration of amino acids in the culture medium, indicating their effect on the regulation of protein synthesis. At least 6 h incubation is needed to reach the maximal values of incorporation. Media containing large amounts of amino acids also showed higher values for oxidation, but the ratio oxidation/incorporation was higher when the amino-acid concentration in the medium was low.