Altered hepatobiliary transport of taurocholic acid in aged rats

Hepatobiliary transport of taurocholic acid was studied in adult (3 months) and old (2 years) rats using an isolated perfused rat liver technique in order to determine the effect of age on hepatic uptake and secretion of bile acids simultaneously. The results were analyzed using a steady-state compartmental model to estimate the uptake and secretion of taurocholic acid. Hepatic secretion was decreased to a greater extent than the uptake in old rats. These changes in transport activities were associated with increases in perfusate and liver bile acid pool sizes. These results can explain the decrease in total pool size and synthesis rate of bile acids observed previously in old rats using in vivo studies. It has been suggested that the age-dependent decrease in bile acid transport capacity of the liver is secondary to the altered lipid composition of the liver plasma membranes of old rats.