title: Nitroglycerin-induced endothelial dysfunction and tolerance involve adverse phosphorylation and S-Glutathionylation of endothelial nitric oxide synthase: beneficial effects of therapy with the AT1 receptor blocker telmisartan.
abstract: OBJECTIVE
  Continuous administration of nitroglycerin (GTN) causes tolerance and endothelial dysfunction by inducing reactive oxygen species (ROS) production from various enzymatic sources, such as mitochondria, NADPH oxidase, and an uncoupled endothelial nitric oxide synthase (eNOS). In the present study, we tested the effects of type 1 angiotensin (AT(1))-receptor blockade with telmisartan on GTN-induced endothelial dysfunction in particular on eNOS phosphorylation and S-glutathionylation sites and the eNOS cofactor synthesizing enzyme GTP-cyclohydrolase I.
  
  
  RESULTS
  Wistar rats were treated with telmisartan (2.7 or 8 mg/kg per day PO for 10 days) and with GTN (50 mg/kg per day SC for 3 days). Aortic eNOS phosphorylation and S-glutathionylation were assessed using antibodies against phospho-Thr495 and Ser1177 or protein-bound glutathione, which regulate eNOS activity and eNOS-dependent superoxide production (uncoupling). Expression of mitochondrial aldehyde dehydrogenase was determined by Western blotting. Formation of aortic and cardiac ROS was assessed by fluorescence, chemiluminescence, and 3-nitrotyrosine/malondialdehyde-positive protein content. Telmisartan prevented endothelial dysfunction and partially improved nitrate tolerance. Vascular, cardiac, mitochondrial, and white blood cell ROS formation were significantly increased by GTN treatment and inhibited by telmisartan. GTN-induced decrease in Ser1177, increase in Thr495 phosphorylation or S-glutathionylation of eNOS, and decrease in mitochondrial aldehyde dehydrogenase expression were normalized by telmisartan.
  
  
  CONCLUSIONS
  These data identify modification of eNOS phosphorylation as an important component of GTN-induced endothelial dysfunction. Via its pleiotropic "antioxidant" properties, telmisartan prevents, at least in part, GTN-induced oxidative stress, nitrate tolerance, and endothelial dysfunction.
authors.affiliation: Second Medical Clinic, Department of Cardiology, Medical Center of Johannes Gutenberg University, Mainz, Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: Knorr
authors.forename: Michael
authors.initials: M
authors.lastname: Hausding
authors.forename: Swenja
authors.initials: S
authors.lastname: Kröller-Schuhmacher
authors.forename: Sebastian
authors.initials: S
authors.lastname: Steven
authors.forename: Matthias
authors.initials: M
authors.lastname: Oelze
authors.forename: Tjebo
authors.initials: T
authors.lastname: Heeren
authors.forename: Alexander
authors.initials: A
authors.lastname: Scholz
authors.forename: Tommaso
authors.initials: T
authors.lastname: Gori
authors.forename: Philip
authors.initials: P
authors.lastname: Wenzel
authors.forename: Eberhard
authors.initials: E
authors.lastname: Schulz
authors.forename: Andreas
authors.initials: A
authors.lastname: Daiber
authors.forename: Thomas
authors.initials: T
authors.lastname: Münzel
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D001562:Benzimidazoles / Q000097:blood / Q000494:pharmacology*; D001565:Benzoates / Q000097:blood / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077333:Telmisartan; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D001565:Benzoates; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D014665:Vasodilator Agents; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D000444:Aldehyde Dehydrogenase; D013762:Tetrahydrofolate Dehydrogenase; D006136:GTP Cyclohydrolase; D005996:Nitroglycerin; D005978:Glutathione; D000077333:Telmisartan