In vitro synthesis of microsomal protein and albumin in young and old rats

Abstract

1. 1. Protein and serum albumin synthesis was investigated with isolated liver microsomes from young and old rats. Albumin synthesis of old rats, based on mg protein, is 50 % higher than that of young rats, but there is no difference in total protein synthesis. 2. 2. The increased albumin synthetic activity resides in the microsomal particles and not in the cell sap. 3. 3. The albumin synthesis of young rats can be stimulated by bleeding. Increased albumin synthesis reaches its peak at 3 h after bleeding and is 40 % higher than in non-bled young rats, whereas in old rats, bleeding does not further increase albumin synthesis. 4. 4. The cell sap fraction from bled rats, either young or old, has a stimulating effect on albumin synthesis by the microsome fraction from young rats.