Evidence that chlorpromazine and prostaglandin E1 but not neomycin interfere with the inositol phospholipid metabolism in intact human platelets

Human platelets that had been prelabelled with 32P]Pi were stimulated with trombin in the presence or absence of neomycin, prostaglandin E1 (PGE1) or chlorpromazine. The content of 32P]Pi in phosphatidylinositol 4-phosphate, phosphatidylinositol 4,5-bisphosphate and phosphatidic acid (PA) were determined. The data demonstrate that PGE1 and chlorpromazine but not neomycin interfere with the tight metabolic relationship that exists between the inositol phospholipids and PA in thrombin-stimulated platelets (1989) Biochem. J. 263, 621-624]. Our results therefore indicate that neomycin does not inhibit signal transduction in intact platelets at the level of the inositol phospholipid metabolism.