Platelet activating factor (PAF-acether) promotes an early degradation of phosphatidylinositol-4,5-biphosphate in rabbit platelets.
32P-Labelled washed rabbit platelets were incubated with 0.6 nM platelet activating factor (PAF-acether), giving a full aggregation and release response within 30-60 s. The major phospholipid changes observed under these conditions were: (1) An increased labelling of phosphatidic acid (PA) within 10 s and of phosphatidylinositol (MPI) at 30 s, reflecting the activation of the MPI cycle via the cytosolic phospholipase C; (2) an enhancement of phosphatidylinositol-4-phosphate (DPI) and phosphatidylinositol-4,5-bisphosphate (TPI) labelling at later incubation times; (3) an early degradation of TPI with a counterbalancing formation of DPI. The latter changes suggest a receptor-mediated stimulation of TPI-phosphomonoesterase, the role of which in the mechanism of platelet activation is discussed.
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000097:blood*; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D011817:Rabbits
D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; C026613:1-0-octadecyl 2-0-acetyl sn-glycero-3-phosphorylcholine