Abstract
The addition of the synthetic chemotactic peptide formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe) to rabbit neutrophils promoted [14C]arachidonic acid incorporation into phosphatidylinositol and lysosomal enzyme release; these two processes increased in parallel with respect to time and peptide concentration and were dependent upon extracellular Ca2+. Cytochalasin B, which augments enzyme release, also enhanced fMet-Leu-Phe-evoked arachidonyl phosphatidylinositol turnover. The peptide did not alter the incorporation of labeled palmitic acid or glycerol into phosphatidylinositol, although 32P turnover was increased within 2 min. Another synthetic peptide, methionyl-leucyl-phenylalanine, failed to enhance arachidonic acid incorporation into phosphatidylinositol and was unable to promote lysosomal enzyme secretion. These results support the hypothesis that fMet-Leu-Phe-induced stimulation of lysosomal enzyme release and Ca2+-dependent turnover of arachidonyl phosphatidylinositol are somehow related. These findings, taken together with our previous studies demonstrating similar changes in membrane phospholipids during ACTH action on adrenocortical cells, suggest that the turnover of arachidonic acid in phospholipids mediated by a Ca2+-dependent phospholipase A2 may represent a general mechanism for producing rapid perturbations in the cell membrane during accelerated secretory activity.
- Copyright © 1981 by The American Society for Pharmacology and Experimental Therapeutics
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