title: Effects of bradykinin on prostaglandin I(2) synthesis in human vascular endothelial cells.
abstract: The effects of bradykinin on the regulatory mechanisms of prostacyclin synthesis in endothelial cells were investigated in association with intracellular Ca(2+) kinetics, cytosolic phospholipase A(2) (cPLA(2)) activity, and mRNA expression of cPLA(2) and prostaglandin H synthase (PGHS) isoforms. Bradykinin enhanced prostacyclin release from endothelial cells time-dependently, but pretreatment with EGTA H-7 or HOE 140 inhibited bradykinin-induced prostacyclin release. Bradykinin increased both the influx of extracellular Ca(2+) and Ca(2+) release from the intracellular Ca(2+) storage sites. These reactions occurred within 5 minutes after bradykinin stimulation. Within 15 minutes, bradykinin activated cPLA(2) to 1.3-fold the control level. The constitutive expressions of mRNA of cPLA(2), PGHS-1, and PGHS-2 was 87, 562, and 47 amol/microg RNA, respectively. With the stimulation of bradykinin, cPLA(2) mRNA increased to 746 amol/microg RNA in 15 minutes, PGHS-1 mRNA increased to 10 608 amol/microg RNA, and PGHS-2 mRNA increased to 22 400 amol/microg RNA in 180 minutes. Pretreatment with cycloheximide superinduced cPLA(2) and PGHS-2 mRNA expression but almost completely inhibited PGHS-1. Pretreatment with EGTA had effects similar to pretreatment with cycloheximide in the case of cPLA(2) and PGHS-1 but did not affect PGHS-2. These findings suggest that the elevation of cPLA(2) activity caused by the increase of intracellular Ca(2+) concentration is important in the early phase of bradykinin-induced prostacyclin synthesis and that the mechanisms regulating cPLA(2) are different from those regulating PGHS isoforms in endothelial cells.
authors.affiliation: Second Department of Medicine, Kyoto Prefectural University of Medicine, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yamasaki
authors.forename: S
authors.initials: S
authors.lastname: Sawada
authors.forename: S
authors.initials: S
authors.lastname: Komatsu
authors.forename: T
authors.initials: T
authors.lastname: Kawahara
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuda
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: A
authors.initials: A
authors.lastname: Toratani
authors.forename: Y
authors.initials: Y
authors.lastname: Kono
authors.forename: T
authors.initials: T
authors.lastname: Higaki
authors.forename: H
authors.initials: H
authors.lastname: Imamura
authors.forename: Y
authors.initials: Y
authors.lastname: Tada
authors.forename: N
authors.initials: N
authors.lastname: Akamatsu
authors.forename: T
authors.initials: T
authors.lastname: Tamagaki
authors.forename: H
authors.initials: H
authors.lastname: Tsuji
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
mesh_terms: D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011464:Epoprostenol / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007527:Isoenzymes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010741:Phospholipases A / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D004533:Egtazic Acid; D015544:Inositol 1,4,5-Trisphosphate; D011464:Epoprostenol; D011451:Prostaglandin-Endoperoxide Synthases; D010741:Phospholipases A; D001920:Bradykinin; D002118:Calcium