Studies on Acute Phase Proteins of Rat Serum. V. Effect of Induced Inflammation on the Synthesis of Albumin and α1-Acid Glycoprotein by Liver Slices

Abstract

Liver slices from normal rats and those suffering from inflammation for 24–48 h were incubated with L-[14C]leucine or D-[I4C]glucosamine. Immunological techniques coupled with radioautography indicated that the microsome fraction prepared from slices contained the subcellular site of synthesis of the polypeptide chain of serum albumin, and the polypeptide and carbohydrate chains of α1-acid glycoprotein; both proteins were also present in the medium in labelled forms. The contents of albumin and α1-acid glycoprotein in the medium and in extracts of liver from experiments with liver slices from control rats and 8–72 h experimental rats were determined using the quantitative precipitin technique. There was a net increase in synthesis of both proteins when slices from control and experimental animals were used, the increase showing up in medium proteins. However, slices from livers from 8–72 h experimental rats had a greater capacity for synthesis of α1-acid glycoprotein and a lower capacity for synthesis of albumin than slices from livers from control rats, the greatest changes occurring with slices from 24 h experimental rats. Changes in synthetic capacities of liver slices from experimental rats for albumin and α1-acid glycoprotein were always accompanied by large increases in specific radioactivities of total medium proteins when experiments involved incubation of slices with L-[3H]leucine and D-[14C]glucosamine. It is suggested that the increase in specific radioactivities of medium proteins following incubation of liver slices from experimental rats with labelled leucine and glucosamine is a characteristic of the response of liver to inflammation, and reflects changes in the capacity of liver for the synthesis of α1-acid glycoprotein and other acute phase serum proteins.