Bile acids and lipids in isolated rat hepatocytes: content, synthesis, and release, as affected by cholestyramine treatment of the donor rats

Abstract

Contents of bile acids and lipids, as well as rates of triglyceride synthesis, were determined in isolated hepatocytes from control or cholestyramine-fed rats (denoted below as ''control'' or ''treated'' hepatocytes, respectively). During a 3-hr incubation period, total bile acid production was markedly higher in ''treated'' cells than in ''control'' cells. With both kinds of cells a marked fall in production rate occurred after the first hour of incubation. Newly produced bile acids appeared in the conjugated form with both kinds of hepatocytes. ''Control'' cells produced only taurine-conjugated, while ''treated'' cells made both taurine-conjugated and glycine-conjugated bile acids. However, with exogenous taurine (0.5 mM), the latter cells also produced taurine-conjugated bile acids only. With both kinds of cells, cholic and beta-muricholic acids, but not dihydroxylated bile acids, appeared as newly formed species during the incubation. Addition of dialyzed rat serum to the incubation did not result in a stimulation of bile acid production, with either kind of hepatocytes. ''Treated'' cells had a slightly higher content of free cholesterol than control cells; contents of other lipids were not different. Fractional release of bile acids and lipids into the medium did not differ between the two kinds of cells. Triglyceride synthesis from added [14C]palmitate (0.5 mM) was 1.8-fold higher in ''treated'' than in ''control'' hepatocytes.