title: Antioxidant and nitric oxide-sparing actions of dihydropyridines and ACE inhibitors differ in human endothelial cells.
abstract: The effects of dihydropyridine Ca2+ channel blockers (DHP) and ACE inhibitors on superoxide formation and nitric oxide (NO) bioavailability were compared in human EA.Hy926 endothelial cells (EC). EC were stimulated 4 h with angiotensin II (Ang II, 10 nM) +/- study drugs. Specific superoxide formation was measured by lucigenin-enhanced chemiluminescence, reduction of cytochrome c and rhodamine-123 fluorescence. Free NO release was determined with an amperometric NO sensor. NADPH oxidase subunits expression was examined with Western Blot. In untreated EC the intracellular superoxide is -64.3 +/- 6.0% decreased compared to Ang II stimulated EC. Elevated extracellular superoxide formation was on a -43.0 +/- 1.7% lower level in untreated EC. The DHP Ca2+-channel agonist BayK8644 and ACE inhibitors captopril and ramiprilat led extracellular superoxide concentration to control level. Enalaprilat blocked extracellular superoxide, the DHP amlodipine and nisoldipine prevented intracellular increases only (n = 8-9, p < 0.05). Icatibant (HOE 140), a kinin-B2 receptor antagonist, attenuated antioxidant actions of all tested agents except of nisoldipine. Ang II-induced superoxide was elevated by the phorbolester PMA and blocked by the protein kinase C (PKC) inhibitor chelerythrine. Suppression of substance P-evoked NO release by Ang II (>70%, n = 6) was reversed by the PKC inhibitor chelerythrine, the DHP amlodipine and nisoldipine and the ACE inhibitor ramiprilat. Further, Ang II reduces Nox-4 expression by 34.5 +/- 4.9. Nox-2 expression was not regulated. DHP and ACE inhibitors exert different antioxidant effects in human EC stimulated with Ang II, but both improve NO bioavailability via bradykinin and modulation of redox-regulating enzymes.
authors.affiliation: Department of Pharmacology, University Hospital, University of Cologne, Cologne, Germany. heinrich.lob@uni-koeln.de
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lob
authors.forename: Anke Claudia
authors.initials: AC
authors.lastname: Rosenkranz
authors.forename: Thomas
authors.initials: T
authors.lastname: Breitenbach
authors.forename: Reinhard
authors.initials: R
authors.lastname: Berkels
authors.forename: Grant
authors.initials: G
authors.lastname: Drummond
authors.forename: Renate
authors.initials: R
authors.lastname: Roesen
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002460:Cell Line; D004095:Dihydropyridines / Q000494:pharmacology*; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000975:Antioxidants; D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D013481:Superoxides; D000804:Angiotensin II; D009569:Nitric Oxide; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; D011493:Protein Kinase C