VLDL-derived fatty acids serve as potent PPAR-α ligands due to efficient delivery. BAEC were transfected with the PPAR α-LBD-GAL4 reporter system, as described in “Methods,” treated for 18 h, and cell lysate assayed for luciferase and β-galoctosidase activity. A: BAEC were exposed to various concentrations of LPL (1, 3, or 10 units/ml) and VLDL (1, 3, 10, or 30 μg/ml), oleic acid (0, 5, 10, or 20 μM at an unbound oleic acid concentration of 2450 nM), or plasma (0–5% v/v). This produced a range of NEFA concentrations, as measured in the cell culture media at the end of treatment. For oleic acid, a linear relationship exists between oleic acid added and NEFA concentration in the cell culture media (data not shown), such that ∼60% of NEFA added remains in the media following incubation with cells. PPAR-α activity is presented as percentage of activation by 10 µM Wy14643, a synthetic PPAR-α ligand. B: Transfected BAEC were incubated with VLDL (10 µg protein/ml) and LPL (10 units/ml) and increasing concentrations of albumin in triplicate. PPAR-α activity is expressed as fold activation over control.