Incorporation Rate of Leucine into Proteins in Human Liver Slices

The rate of incorporation of leucine into hepatic proteins in liver slices from 42 patients was studied. Zero order kinetics for the incorporation of leucine in relation to the incubation time and to the amount of incubated proteins were obtained, provided that the medium contained a complete amino acid mixture with a concentration 4 times that of normal human serum. – Inulin space and water content of the preparation were of the same magnitude as reported for rat liver. The presence of fructose (5.5 mM) in the medium caused an inhibition of the rate of incorporation of leucine into pro teins. Insulin in the medium, however, stimulated tho incorporation rate. – Assuming that the rate of incorporation of leucine into hepatic proteins is representative of protein synthesis, the half‐life of liver proteins can be calculated to be 35 days for subjects below 60 years of age. For those who were older than 60 years, the protein turnover rate was approximately 30% higher.