title: Specific incorporation of 5-hydroxy-6,8,11,14-eicosatetraenoic acid into phosphatidylcholine in human endothelial cells.
abstract: The incorporation of hydroxyeicosatetraenoic acids (HETEs) into cellular lipids was studied in cultures of human umbilical vein endothelial cells. 5-[3H]HETE was incorporated into the phospholipids (8%) and neutral lipids (15.5%). The uptake was at half maximum after 15 min and reached a plateau after 1 h. The incorporation occurred mainly into phosphatidylcholine (6.3%) with minimal uptake into phosphatidylserine and phosphatidylinositol (0.6%) or phosphatidylethanolamine (1.2%). There was no uptake of 12-[3H]HETE, 15-[3H]HETE or [3H]leukotriene B4 into phospholipids. Treatment of the phosphatidylcholine fraction with phospholipase A2 released 64% of the 5-[3H]HETE with 26% remaining in the lysophosphatidylcholine fraction. This indicates that the majority of the 5-HETE was in the sn-2 position. Unlabeled 5-HETE and arachidonic acid inhibited the uptake of 5-[3H]HETE into phosphatidylcholine with an ID50 of 2.5 and 1.25 microM, respectively. Stearic acid and 15-HETE were not effective inhibitors. Histamine, which activates phospholipases, increased the uptake of 5-[3H]HETE into phosphatidylcholine by 3-fold. Both 5-[3H]HETE and 12-[3H]HETE were incorporated into the neutral lipids of the cells. Analysis of the neutral lipid fraction revealed that 5-[3H]HETE was incorporated into mono-, di- and triacylglycerols but not cholesterol esters. Incorporation of 5-HETE into cellular lipids reduced histamine- and arachidonic acid-stimulated synthesis of 6-ketoprostaglandin F1 alpha and prostaglandin E2 in a concentration-related manner. Angiotensin I converting enzyme activity was not changed. Thus, 5-HETE is incorporated specifically into phosphatidylcholine and glycerol esters of human endothelial cells and this incorporation inhibits prostaglandin synthesis in these cells.
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D003331:Coronary Vessels / Q000378:metabolism; D004727:Endothelium / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism* / Q000494:pharmacology; D050356:Lipid Metabolism; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D011453:Prostaglandins / Q000096:biosynthesis; D014470:Umbilical Cord / Q000378:metabolism
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D010713:Phosphatidylcholines; D011453:Prostaglandins; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; D006632:Histamine; D007703:Peptidyl-Dipeptidase A