title: Rapid decrease of phosphatidylinositol 4,5-bisphosphate in thrombin-stimulated platelets.
abstract: The addition of thrombin to horse platelets prelabeled with 32P induces a rapid decrease of the radioactivity from phosphatidylinositol 4,5-bisphosphate. Maximum loss of the radioactivity from phosphatidylinositol 4,5-bisphosphate occurs with 10 s of stimulation and is followed by an increased incorporation of 32P into this lipid. The stimulation of phosphatidylinositol 4,5-bisphosphate loss by thrombin is concentration-dependent. The ionophore A23187, which mobilizes Ca2+, is ineffective in inducing the degradation of phosphatidylinositol 4,5-bisphosphate. Measurements of polyphosphoinositides by phosphorus estimation show that, 10 s after thrombin stimulation, there is a decrease of 15-20% of the total phosphatidylinositol 4,5-bisphosphate without any significant change in phosphatidylinositol 4-monophosphate. It appears that thrombin causes a rapid and transient degradation of phosphatidylinositol 4,5-bisphosphate and that this effect might be related to the initiation of platelet activation.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D006736:Horses; D007700:Kinetics; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000096:biosynthesis / Q000097:blood*; D013917:Thrombin / Q000502:physiology*
chemical_list: D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D000001:Calcimycin; D013917:Thrombin