The effects of low density lipoprotein and high density lipoprotein on phosphoinositide hydrolysis in bovine aortic endothelial cells.
Low density lipoprotein (LDL) and high density lipoprotein (HDL3) were tested for their ability to induce inositol phospholipid turnover and inositol phosphate production in bovine aortic endothelial cells (BAEC). The production of inositol phosphates following hydrolysis of the phosphoinositides was demonstrated by two methods; release of [3H]inositol phosphates after labelling with [3H]myo-inositol and by a direct binding assay for inositol 1,4,5-trisphosphate (InsP3). Acute exposure to LDL induced InsP3 release at low concentrations of the lipoprotein within the physiological range of LDL in tissues. HDL3 did not cause any release of the inositol phosphates. Pre-incubation of BAEC with HDL3 suppressed bradykinin- and LDL-induced inositol phosphate production in BAEC in a concentration-dependent manner. It is concluded that LDL acutely stimulates phosphoinositide breakdown and that pre-incubation of cells with HDL3 inhibits this effect. The mechanism responsible for these effects remains to be elucidated.
Myers
D E
DE
Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Victoria, Australia.
Fidge
N H
NH
Stanton
H
H
Larkins
R G
RG
D000818:Animals; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism / Q000494:pharmacology*; D053440:Lipoproteins, HDL3; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*
D007295:Inositol Phosphates; D008075:Lipoproteins, HDL; D053440:Lipoproteins, HDL3; D008077:Lipoproteins, LDL; D010716:Phosphatidylinositols