title: Bradykinin-induced changes in phosphoinositides, inositol phosphate production and intracellular free calcium in cultured bovine aortic endothelial cells.
abstract: Acute hydrolysis of phosphoinositides has been demonstrated in bovine aortic endothelial cells (BAEC) treated with bradykinin (BK) (10(-7)M). The first phosphoinositide to decrease was phosphatidylinositol-4,5-bisphosphate (PIP2) indicating this to be the initial substrate of phospholipase action. Other lipid changes associated with the stimulation of BAEC were an increase in diacylglycerol (DAG) and arachidonic acid (AA) with a sustained production of phosphatidic acid (PA). The changes in cell phospholipids were accompanied by the release of inositol phosphates. Inositol-1,4,5-trisphosphate (Ins-1,4,5-P3) was produced within 10 s of stimulation with BK. There was no evidence for the production of inositol-1,3,4-trisphosphate. The release of ionic calcium (Ca2+) intracellularly was demonstrated. The timecourse of the rise in intracellular Ca2+ was consistent with the timecourse of production of IP3. Intracellular Ca2+ rose from 127 +/- 21 nM to 462 +/- 27 nM. The Ca2+ peak was at 7.0 +/- 0.4 s and took 3 min to reach a steady state which remained above the basal level. When extracellular Ca2+ was depleted in the extracellular medium a spike of intracellular Ca2+ release was measured with an immediate return to basal. Entry of extracellular Ca2+ into the cell after ionophore A23187 treatment does not induce inositol phosphate release, indicating that phosphoinositide hydrolysis is likely to be the cause rather than consequence of the elevation in cytosolic Ca2+. These data indicate action of phospholipase C (PLC) on PIP2 after BK stimulation of BAEC with the subsequent production of InsP3 causing the resulting intracellular Ca2+ release.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: D E
authors.initials: DE
authors.lastname: Myers
authors.forename: R G
authors.initials: RG
authors.lastname: Larkins
mesh_terms: D000818:Animals; D001011:Aorta; D001095:Arachidonic Acids / Q000378:metabolism; D001920:Bradykinin / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004075:Diglycerides / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010740:Phospholipases / Q000378:metabolism
chemical_list: D001095:Arachidonic Acids; D004075:Diglycerides; D007295:Inositol Phosphates; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D000001:Calcimycin; D010740:Phospholipases; D001920:Bradykinin; D002118:Calcium