Thrombocytic membranes were incubated with [μ-32P] ATP in the presence of Mg2+ to observe the effect of tetramethylpyrazine on incorporation of 32 P into phospholipids and proteins. The result showed there are phosphatidylinositol kinase and phosphatidylinositol 4 - phosphate kinase in platelet membranes, while almost none or very little in cytosol. ATP stimulated the phosphory-lation of phosphoinositides. Tetram- ethylpyrazine inhibited the phosphoryla-tion of phosphatidylinositol 4-phosphate and 20K protein in platelets. Concentrations givin...