Oxysterol mediated changes in fatty acid distribution and lipid synthesis in cultured bovine aortic smooth muscle cells.

We studied the actions of oxysterols on fatty acid distribution and lipid synthesis in cultured bovine aortic smooth muscle cells. Cultures were labeled with [1-14C]arachidonate or [1-14C]oleate. During a 24-hr incubation, 25- or 22R-hydroxycholesterol enhanced the incorporation of label into triglycerides, concomitant with a reduction in the labeling of phospholipids. Cholestantriol or 20-hydroxycholesterol had the opposite effects. They caused a higher incorporation of radiolabel into phospholipids and a reduction of labeling of triacylglycerols. Similar changes were seen in cells labeled with [1-14C]acetate. Therefore, we conclude that oxysterols can promote changes in the distribution of fatty acids between neutral lipids and phospholipids through mechanisms that still need to be clarified.