Use of primary cultures of rat hepatocytes for the study of ageing and caloric restriction.

Primary cultures of hepatocytes are widely used to investigate liver function, but this technology has not been exploited fully in the study of ageing and caloric restriction (CR). Hepatocytes were isolated from adult and aged, fully fed, and calorie restricted male Sprague-Dawley rats and their viability and biochemical status assessed over 48h in primary culture. The in vivo differences in cellular protein and DNA content due to age and CR were maintained over the 48h experimental period. The results of this study confirm earlier reports that protein synthesis and degradation rates decline with age in liver tissue, and this decline is retarded by CR. Rates of protein synthesis and degradation in the first year of life were depressed in response to CR feeding and were only significantly higher than recorded for control animals during the second year of life. Cells from rats of both ages and diets maintained linear rates of extracellular protein synthesis, intracellular protein synthesis, protein degradation and albumin secretion between 24 and 48h in culture. These findings indicate that hepatocytes from CR rats did not respond adversely to the relatively rich culture medium and cells from CR animals did not immediately revert to the fully fed phenotype.