Synthesis and degradation of liver proteins in young and old rats

Abstract

The report describes the study of the in vivo synthesis and degradation of ferritin as an example of an intracellular liver protein, albumin, as an example of a protein secreted by the liver, and total liver protein in young and old rats. In addition, possible age changes in the amounts of these proteins were investigated. Several biochemical changes occur with age. 1. 1. There is twice as much ferritin and about 4 times as much iron in old rat liver ferritin as in livers from young rats. 2. 2. The accumulation of ferritin in old rats appears to be due to a decreased rate of degradation. 3. 3. Albumin synthesis is increased in old rats. 4. 4. Albumin synthesis in young rats can be increased by removing blood from the animals. Old rats do not respond to the removal of blood by increased albumin synthesis. Finally, there is a labeling pattern of ferritin with time which is different from that of total liver protein suggesting two distinct steps, synthesis of subunits and assembly into ferritin molecules. The results suggest that in order to study age-related changes one should consider changes in specific proteins that might be masked if only total proteins are investigated. In addition, certain changes might become apparent only if the system is manipulated, in our case, induction of albumin synthesis by removal of blood from the animal