Effect of hydrocortisone and nicotinamide on gamma glutamyltransferase in primary cultures of rat hepatocytes.

Isolated rat hepatocytes cultured on collagen coated plates exhibit a gradual fetal phenotypic change during time in culture. The fetal liver marker gamma glutamyltransferase (GGT) was used to follow this change. Inasmuch as a significant overgrowth of nonparenchymal liver derived cells is seen frequently in primary cultures of hepatocytes, a technique was utilized that corrects for the presence of nonparenchymal cells. In media supplemented with either hydrocortisone (10(-5) M) or nicotinamide (25 mM) the original epithelial morphology of hepatocytes was preserved for a longer period of time than in unsupplemented media. Hepatocytes in unsupplemented media exhibited an increase in GGT specific activity over time. Hydrocortisone (10(-5) M) induced an increase in GGT activity compared to controls. Nicotinamide (25 mM) inhibited the increase in GGT activity compared to the unsupplemented hepatocytes. Our results indicate that GGT is regulated by hydrocortisone and nicotinamide.