Remodeling of arachidonate-containing phosphoglycerides within the human neutrophil.
Initial incorporation and subsequent remodeling of 16 phosphoglyceride molecular species containing arachidonate in the human neutrophil have been studied. Neutrophils were pulse-labeled with [3H]arachidonic acid (AA) for 5 min, then phospholipids were analyzed either at this time point or after a subsequent 120-min incubation. [3H]AA was found to be incorporated into phosphoglycerides phosphatidylinositol (PI) greater than phosphatidylcholine (PC) greater than phosphatidylethanolamine (PE) by 5 min. Incorporation of [3H]AA was not related to pool size, but reflected an increase in phosphoglyceride turnover. Following the 120-min incubation, only PE gained a significant amount of labeled arachidonate. Specific activity analysis revealed that PI contained the highest labeled/unlabeled ratio at both 5 min and 120 min. After the initial 5-min pulse, the majority of [3H]arachidonate was incorporated into 1-acyl-2-[3H]arachidonoyl-sn-glycero-3-PC, -PE, and -PI showing no preference for fatty acyl chains at the sn-1 position. However, [3H]AA was remodeled into 1-alkyl-acyl-and 1-alk-1-enyl-acyl-sn-glycero-3-PC and -PE molecular species in those neutrophils incubated for the additional 120 min. Specific activities of [3H]AA within all diacyl molecular species were initially higher relative to those alkyl-acyl and alk-1-enyl-acyl molecular species, but for PC and PE became more uniform as label shifted into ether and plasmalogen pools during the additional 120-min incubation. In contrast, the specific activity of 1-stearoyl-2-arachidonoyl-sn-glycero-3-PI remained constant throughout the 120-min incubation.
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood*; D005994:Glycerophosphates / Q000096:biosynthesis / Q000097:blood*; D006801:Humans; D007700:Kinetics; D009504:Neutrophils / Q000378:metabolism*; D010743:Phospholipids / Q000096:biosynthesis / Q000097:blood; D011865:Radioisotope Dilution Technique; D014316:Tritium
D001095:Arachidonic Acids; D005994:Glycerophosphates; D010743:Phospholipids; D014316:Tritium; D016718:Arachidonic Acid