Utilization of gammalinolenic acid by mouse peritoneal macrophages.
To delineate the metabolism of gammalinolenic acid (18:3(n-6] by macrophages, primary cultures of resident mouse peritoneal macrophages were incubated with [14C]18:3(n-6). At 3, 6 or 20 h, the majority (greater than 85%) of the radiolabel was recovered in cell phospholipids. With increasing time of incubation, a relative reduction of 14C in glycerophosphocholine (ChoGpl, 58.1% to 46.2%) was noted. This was offset by a corresponding increase in glycerophosphoethanolamine (EtnGpl) labeling (from 8.8% to 18.9%). There was also a time-dependent redistribution of 14C from diacyl to ether-containing phospholipid subclasses in ChoGpl and EtnGpl. Analysis of cell extracts by reverse-phae HPLC following transmethylation demonstrated that 18:3(n-6) was extensively elongated (greater than 80%) to dihomogammalinolenic acid (20:3(n-6] by 3 h. The major radiolabeled phospholipid molecular species in the diacyl (PtdCho) and alkylacylglycerophosphocholine (PakCho) subclasses was 16:0-20:3(n-6). In contrast, diacyl (PtdEtn) and alkenylacylglycerophosphoethanolamine (PlsEtn) subclasses contained primarily [14C]18:0-20:3(n-6) and 16:0-20:3(n-6), respectively. Macrophages prelabeled with [14C]18:3(n-6) for 20 h and stimulated with calcium ionophore A23187 or zymosan synthesized [14C]prostaglandin E1 (PGE1). These data demonstrate that macrophages possess an active long chain polyunsaturated fatty acid elongase capable of converting 18:3(n-6) to 20:3(n-6) which can, upon stimulation, be converted to PGE1.
Chapkin
R S
RS
Department of Animal Science, Texas A & M University, College Station 77843-2471.
Coble
K J
KJ
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism; D002478:Cells, Cultured; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D008042:Linolenic Acids / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D010101:Oxygen Consumption; D010529:Peritoneal Cavity; D010743:Phospholipids / Q000378:metabolism; D017965:gamma-Linolenic Acid
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004042:Dietary Fats, Unsaturated; D008042:Linolenic Acids; D010743:Phospholipids; D017965:gamma-Linolenic Acid