INTERACTION OF LYSOPHOSPHATIDYLCHOLINE WITH AORTIC ENDOTHELIAL-CELLS

To better understand the vascular actions of lysophosphatidylcholine (lysoPC), we studied the interaction of [1-C-14]palmitate-labeled lysoPC with bovine aortic endothelial cells. These cells took up lysoPC from media containing albumin, low-density lipoproteins (LDL), or acetyl-LDL. Uptake occurred faster than conversion to phosphatidylcholine (PC), leading to some lysoPC accumulation in endothelial lipids. Endothelial cell monolayers grown on micropore filters took up lysoPC from both apical and basolateral surfaces, preventing substantial amounts from passage across the endothelial monolayer. However, lysoPC present in the interstitial medium of an endothelial-smooth muscle coculture was incorporated primarily by the smooth muscle cells. Endothelial cells grown on filters released lysoPC into both the apical and basolateral medium in the presence of albumin or lipoproteins. Exposure to 50-mu-M lysoPC produced no evidence of endothelial cytotoxicity, but prostaglandin (PG)I2 production was reduced. These studies suggest that the endothelium can participate in the processing of circulating lysoPC and, through basolateral uptake, can facilitate the removal of lysoPC formed within the arterial wall. By decreasing PGI2 output, however, exposure to high concentrations of lysoPC may reduce the antithrombotic and vasodilator capacity of the endothelium.