1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine: a novel source of arachidonic acid in neutrophils stimulated by the calcium ionophore A23187.

Rabbit peritoneal neutrophils incorporated [14C]arachidonic acid into seven molecular species of choline-containing phosphoglycerides. These 2-[14C]arachidonoyl species differed with respect to the alkyl ether or acyl residue bound at the sn-1 position; four of the seven were ether-linked. Stimulation with calcium ionophore A23187 induced a proportionate release of arachidonate from all seven molecular species: 40% of the released arachidonate came from alkyl ether species. Thus, 1-O-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine (GPC) is a significant source of metabolizable arachidonic acid. Since 1-O-alkyl-2-lyso-GPC is the metabolic precursor of platelet activating factor, these results further interrelate pathways forming arachidonate metabolites and platelet activating factor; they also supply a rationale for the observation that both classes of stimuli form concomitantly during cell activation.