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[Effect of lipoprotein on phosphatidylinositol -4,5-bisphosphate and phosphatidic acid in platelet]
1Department of Pharmacology, Faculty of Basic Medicine, Peking Union Medical College, Beijing.
Abstract:
Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were separated from normal human serum and incubated with 32P labelled human platelets. Studies were designed to explore the effects of thrombin, LDL, HDL plus LDL on the changes of the important metabolites: phosphatidylinositol-4,5-bisphosphate (PIP2) and phosphatidic acid (PA) of phosphatidylinositol cycle (PI). The results indicated that both thrombin and LDL caused a significant decrease of PIP2 within 15 seconds. Then, they gradually returned to the control level. This was accompanied simultaneously by a significant increase of PA level for 60 seconds in time-dependent manner. The effects of thrombin or LDL on PIP2 decrease and PA increase were also both dose-dependent. In addition, HDL significantly antagonized the decrease of PIP2 and increase of PA induced by LDL. It is suggested that PI cycle is closely related to atherosclerosis.