title: Chronic therapy with isosorbide-5-mononitrate causes endothelial dysfunction, oxidative stress, and a marked increase in vascular endothelin-1 expression.
abstract: OBJECTIVE
  Isosorbide-5-mononitrate (ISMN) is one of the most frequently used compounds in the treatment of coronary artery disease predominantly in the USA. However, ISMN was reported to induce endothelial dysfunction, which was corrected by vitamin C pointing to a crucial role of reactive oxygen species (ROS) in causing this phenomenon. We sought to elucidate the mechanism how ISMN causes endothelial dysfunction and oxidative stress in vascular tissue.
  
  
  RESULTS
  Male Wistar rats (n= 69 in total) were treated with ISMN (75 mg/kg/day) or placebo for 7 days. Endothelin (ET) expression was determined by immunohistochemistry in aortic sections. Isosorbide-5-mononitrate infusion caused significant endothelial dysfunction but no tolerance to ISMN itself, whereas ROS formation and nicotinamide adenine dinucleotidephosphate (NADPH) oxidase activity in the aorta, heart, and whole blood were increased. Isosorbide-5-mononitrate up-regulated the expression of NADPH subunits and caused uncoupling of the endothelial nitric oxide synthase (eNOS) likely due to a down-regulation of the tetrahydrobiopterin-synthesizing enzyme GTP-cyclohydrolase-1 and to S-glutathionylation of eNOS. The adverse effects of ISMN were improved in gp91phox knockout mice and normalized by bosentan in vivo/ex vivo treatment and suppressed by apocynin. In addition, a strong increase in the expression of ET within the endothelial cell layer and the adventitia was observed.
  
  
  CONCLUSIONS
  Chronic treatment with ISMN causes endothelial dysfunction and oxidative stress, predominantly by an ET-dependent activation of the vascular and phagocytic NADPH oxidase activity and NOS uncoupling. These findings may explain at least in part results from a retrospective analysis indicating increased mortality in post-infarct patients in response to long-term treatment with mononitrates.
authors.affiliation: 2nd Medical Clinic, Department of Cardiology, Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Oelze
authors.forename: Maike
authors.initials: M
authors.lastname: Knorr
authors.forename: Swenja
authors.initials: S
authors.lastname: Kröller-Schön
authors.forename: Sabine
authors.initials: S
authors.lastname: Kossmann
authors.forename: Anna
authors.initials: A
authors.lastname: Gottschlich
authors.forename: Robert
authors.initials: R
authors.lastname: Rümmler
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schuff
authors.forename: Steffen
authors.initials: S
authors.lastname: Daub
authors.forename: Christopher
authors.initials: C
authors.lastname: Doppler
authors.forename: Hartmut
authors.initials: H
authors.lastname: Kleinert
authors.forename: Tommaso
authors.initials: T
authors.lastname: Gori
authors.forename: Andreas
authors.initials: A
authors.lastname: Daiber
authors.forename: Thomas
authors.initials: T
authors.lastname: Münzel
mesh_terms: D000818:Animals; D001011:Aorta; D006152:Cyclic GMP / Q000378:metabolism; D019332:Endothelin-1 / Q000378:metabolism* / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007548:Isosorbide Dinitrate / Q000031:analogs & derivatives* / Q000633:toxicity; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000009:adverse effects*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism
chemical_list: D019332:Endothelin-1; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D013481:Superoxides; D052250:Nitric Oxide Synthase Type III; D019255:NADPH Oxidases; D006152:Cyclic GMP; D007548:Isosorbide Dinitrate; C030397:isosorbide-5-mononitrate; D019331:NG-Nitroarginine Methyl Ester