title: Lack of involvement of extracellular signal-regulated kinase (ERK) in the agonist-induced endothelial nitric oxide synthesis.
abstract: In a recent paper, it was shown that stimulation of endothelial cells with bradykinin (BK) leads to phosphorylation of endothelial nitric oxide synthase (eNOS) mediated by extracellular signal-regulated kinase (ERK) (J. Biol. Chem. 275 (2000) 30707). Since in vitro phosphorylation by ERK reduced the catalytic activity of eNOS, it was suggested that this mechanism may be an important determinant of nitric oxide signalling in endothelial cells. To explore the physiological role of ERK as regulator of nitric oxide synthesis in intact cells, we measured the effects of the kinase inhibitor PD 98059 on BK- and ATP-induced nitric oxide formation in cultured endothelial cells and isolated vascular smooth muscle strips. PD 98059 completely inhibited ERK activation by BK and ATP in porcine aortic endothelial cells without affecting eNOS activation. Moreover, PD 98059 did not potentiate relaxation of isolated porcine pulmonary arteries to BK or ATP, indicating that ERK-catalysed eNOS phosphorylation does not contribute to the regulation of nitric oxide formation in intact cells or tissues.
authors.affiliation: Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Universitätsplatz 2, A-8010 Graz, Austria. kurt.schmidt@uni-graz.at
authors.forename: Kurt
authors.initials: K
authors.lastname: Schmidt
authors.forename: Hanan D
authors.initials: HD
authors.lastname: Gibraeil
authors.forename: Bernd
authors.initials: B
authors.lastname: Mayer
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D013552:Swine
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D020928:Mitogen-Activated Protein Kinases; D001920:Bradykinin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium