This study examines the patterns of response of primary cultures of hamster hepatocytes to increased delivery of
glucose or
oleate. Increased
glucose in the medium produced: (1) increased
triglyceride in the cells and the medium; (2) no change in
cholesterol ester in the cells or the medium; (3) no change in apo B100 secreted into the medium; (4) more apo B100 particles within the VLDL range with an increase in the
VLDL triglyceride to apo B100 ratio. By contrast, increased
oleate in the medium resulted in: (1) increased
triglyceride in the cells and the medium; (2) increased
cholesterol ester in the cells and the medium; and (3) increased apo B100 secreted into the medium. Important differences in the intracellular metabolism of
triglyceride and
cholesterol ester were also documented. Under all circumstances, there was substantially more radiolabelled
triglyceride (overall eight times more) in the cell than in the medium, indicating that up to 90% of the newly synthesized
triglyceride enters the cellular pool rather than being secreted with apo B100. By contrast, almost half of the newly synthesized
cholesterol ester molecules were secreted with apo B100, pointing to an equal probability of entering the cell storage pool as opposed to being secreted. The data establish therefore two patterns of response of the liver to increased
triglyceride synthesis depending on whether the substrate drive is
glucose or
oleate.