ACTIVATION OF PHOSPHOLIPASE-D IN RABBIT NEUTROPHILS BY FMET-LEU-PHE IS MEDIATED BY A PERTUSSIS TOXIN-SENSITIVE GTP-BINDING PROTEIN THAT MAY BE DISTINCT FROM A PHOSPHOLIPASE C-REGULATING PROTEIN

Stimulation by N-formyl-Met-Leu-Phe (fMLP) of rabbit peritoneal neutrophils, in which phosphatidylcholine was preferentially labeled with 1-O-[H-3]octadecyl lyso platelet-activating factor, activated phospholipase D, resulting in the formation of [H-3]PA from [H-3]PC. A direct activator of GTP-binding proteins (G-proteins), NaF, also stimulated [H-3]PA formation. fMLP-stimulated [H-3]PA formation was inhibited by pertussis toxin (IAP) in a time- and dose-dependent manner. IAP also inhibited fMLP-stimulated IP3 formation, but the inhibition of IP3 formation was significantly greater than that of [H-3]PA formation. These results indicate that activation of phospholipase D by fMLP in rabbit neutrophils is mediated by an IAP-sensitive G-protein that may be distinct from a phospholipase C-regulating protein.