title: Bradykinin stimulation of inositol polyphosphate production in porcine aortic endothelial cells.
abstract: Bradykinin stimulation of inositol polyphosphate production was followed using [3H]inositol-labeled porcine aortic endothelial cells grown in culture. Bradykinin stimulated a significant increase in inositol trisphosphate (IP3) production within 15 s. This increase reached a maximum value of 5-fold above control at 30 s and returned toward baseline by 90 s. Production of inositol bisphosphate increased with time reaching 4-fold by 60 s. Bradykinin stimulated the production of IP3 and inositol biphosphate in a dose-dependent manner with an EC50 of 9 X 10(-9) M. Labeled pools of phosphatidylinositol-4,5-bisphosphate (PIPP) decreased by 50% within 30 s, corresponding to the rise in IP3, while labeled lysophosphatidylinositol pools increased 3-fold by 60 s. Pertussis toxin, a protein which ribosylates GTP-binding proteins, did not inhibit bradykinin-stimulated inositol polyphosphate production. Incubation of labeled cells in the absence of extracellular Ca2+ also did not affect bradykinin-stimulated inositol polyphosphate production. Further, A23187, a Ca2+ ionophore, failed to stimulate PIPP metabolism. Finally, Ca2+ influx into cell monolayers occurred with a time course which paralleled rather than preceded the increase in IP3 levels. These data suggest that bradykinin stimulates phospholipase C metabolism of PIPP to IP3 by a mechanism which does not contain a pertussis toxin sensitive GTP-binding protein. Also, this receptor-linked phospholipase C activity does not appear to be activated by extracellular Ca2+ influx. The results support the proposal that IP3 production initiates Ca2+ mobilization and suggest that the calcium-dependent step in arachidonate release is distal to IP3 production.
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism*; D001920:Bradykinin / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004727:Endothelium / Q000187:drug effects / Q000378:metabolism*; D006023:Glycoproteins; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000096:biosynthesis*; D007700:Kinetics; D037342:Pertussis Toxin; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification; D049231:Saposins; D049128:Sphingolipid Activator Proteins; D013403:Sugar Phosphates / Q000096:biosynthesis*; D013552:Swine; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D006023:Glycoproteins; D007295:Inositol Phosphates; D011506:Proteins; D049231:Saposins; D049128:Sphingolipid Activator Proteins; D013403:Sugar Phosphates; D010566:Virulence Factors, Bordetella; D007294:Inositol; D037342:Pertussis Toxin; D001920:Bradykinin