The in vivo transformation of phospholipid vesicles to a particle resembling HDL in the rat.

Phospholipid vesicles containing 14 C-labeled cholesteryl oleate or lecithin were injected intravenously into rats. A change in the physical properties of the vesicles was observed in plasma shortly after injection. The radioactive markers became associated with a particle similar to high density lipoprotein (HDL) in density and size. A similar change occurred when vesicles were incubated with plasma in vitro. The turnover in plasma of labeled cholesteryl oleate vesicles was studied and found to disappear exponentially over a 10-hour period. No hydrolysis of labeled cholesteryl oleate was observed in plasma, but uptake and hydrolysis did occur in liver.