Regulation of cholesterol metabolism in fetal rabbit aorta: Role of amniotic fluid factors

This study shows that amniotic fluid enhances cholesterol esterification in arterial wall, as measured by in vitro assay of acyl-CoA:cholesterol acyltransferase (ACAT) activity and by incorporation of oleic acid to cholesteryl esters in cultured fetal aortas and smooth muscle cells. This property is mostly evident in the fraction of molecular weight >100,000 and it is abolished by delipidation, indicating that stimulating factor is probably lipoprotein in nature. Despite an increased cholesterol esterification by the presence of amniotic fluid in medium of cultured fetal aortas, the content of cholesterol and cholesteryl esters was much lower. The cellular structures are better preserved in explants cultured with amniotic fluid than in control animals. This study indicates that amniotic fluid contains factors that may have a pronounced effect on arterial wall during development.