Arachidonic acid mobilization among phospholipids in murine mastocytoma P-815 cells: role of et her4 in ked phospholipids

Abrtract The ethanolamine-containing glycerophospholipids, choline-containing glycerophospholipids, and phosphatidylinmitol fractions are major sources of arachidonic acid in murine mastocytoma P-815 cloned cells. The choline-linked fraction contained high arachidonic acid contents in 1-0-alkyl-2-acyl(18%) and 1,2-diacyl-sn-glycero-3-phosphocholine (ll%), with smaller amounts in l-O-alk-l'-enyl-2-acyl species, whereas the arachidonic acid content of the ethanolamine-linked fraction was high in 1-0alk-11-enyl-2-acyl (26%) and 1,2-diacyl species (15%) and low in 1-0-alkyl-2-acyl species. The uptake and transfer of ['Hlarachidonic acid into the 1,2-diacyl and ether classes of cholinecontaining glycerophospholipids and ethanolamine-containing glycerophospholipids in mastocytoma cells were examined. There was very rapid incorporation of radioactive arachidonic acid into mastocytoma cells that leveled off after 30 min. By labeling cells with ['H]arachidonic acid for 7.5 min, the radioactivity was recovered in the choline-containing glycerophospholipids (43%), phosphatidylimitol(32 %), and ethanolamine-containing glycerophospholipids (20%) with little in other phospholipids, neutral lipid, or free fatty acid fractions. Upon reincubation of the mastocytoma cells in the radiolabel-free medium, the [ SH]arachidonate radioactivity was gradually lost from the choline-containing glycerophospholipids fraction and, concomitantly, increased in ethanolamine-containing glycerophospholipids. At the zero time of reincubation, most of the radioactivity was recovered in the 1,2-diacyl species of both choline-containing glycerophospholipids and ethanolamine-containing glycerophospholipids. With increasing time of reincubation, the radioactivity rapidly decreased from 1,2-diacyl-m-glycero-3-phosphocholme, with a concurrent increase in l-0-alkyl-2-acyl-sn-glycero-3-phosphocholine a d 1-0-alkl'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine. Such gradual transfer of arachidonic acid may result in its preferential enrichment in these ether phospholipids, especially in ethanolamine plasmalogen.-Yorhioka, S., S. Nakashima, Y. Okano, and Y. Noeawa. Arachidonic acid mobilization among phospholipids in murine mastocytoma P-815 cells: role of ether-linked phospholipids. J. Lipid Res. 1986. 27: 939-944.