Mitochondrial oxidative stress and nitrate tolerance--comparison of nitroglycerin and pentaerithrityl tetranitrate in Mn-SOD+/- mice.
BACKGROUND
Chronic therapy with nitroglycerin (GTN) results in a rapid development of nitrate tolerance which is associated with an increased production of reactive oxygen species (ROS). According to recent studies, mitochondrial ROS formation and oxidative inactivation of the organic nitrate bioactivating enzyme mitochondrial aldehyde dehydrogenase (ALDH-2) play an important role for the development of nitrate and cross-tolerance.


METHODS
Tolerance was induced by infusion of wild type (WT) and heterozygous manganese superoxide dismutase mice (Mn-SOD+/-) with ethanolic solution of GTN (12.5 mug/min/kg for 4 d). For comparison, the tolerance-free pentaerithrityl tetranitrate (PETN, 17.5 mug/min/kg for 4 d) was infused in DMSO. Vascular reactivity was measured by isometric tension studies of isolated aortic rings. ROS formation and aldehyde dehydrogenase (ALDH-2) activity was measured in isolated heart mitochondria.


RESULTS
Chronic GTN infusion lead to impaired vascular responses to GTN and acetylcholine (ACh), increased the ROS formation in mitochondria and decreased ALDH-2 activity in Mn-SOD+/- mice. In contrast, PETN infusion did not increase mitochondrial ROS formation, did not decrease ALDH-2 activity and accordingly did not lead to tolerance and cross-tolerance in Mn-SOD+/- mice. PETN but not GTN increased heme oxygenase-1 mRNA in EA.hy 926 cells and bilirubin efficiently scavenged GTN-derived ROS.


CONCLUSIONS
Chronic GTN infusion stimulates mitochondrial ROS production which is an important mechanism leading to tolerance and cross-tolerance. The tetranitrate PETN is devoid of mitochondrial oxidative stress induction and according to the present animal study as well as numerous previous clinical studies can be used without limitations due to tolerance and cross-tolerance.
Mollnau
Hanke
H
The 2nd Medical Clinic, Johannes Gutenberg-University, Mainz, Germany. mollnau@uni-mainz.de <mollnau@uni-mainz.de>
Wenzel
Philip
P
Oelze
Matthias
M
Treiber
Nicolai
N
Pautz
Andrea
A
Schulz
Eberhard
E
Schuhmacher
Swenja
S
Reifenberg
Kurt
K
Stalleicken
Dirk
D
Scharffetter-Kochanek
Karin
K
Kleinert
Hartmut
H
Münzel
Thomas
T
Daiber
Andreas
A
D000109:Acetylcholine / Q000494:pharmacology; D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001663:Bilirubin / Q000378:metabolism; D002460:Cell Line; D004334:Drug Administration Schedule; D004361:Drug Tolerance; D016166:Free Radical Scavengers / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008929:Mitochondria, Heart / Q000378:metabolism*; D005996:Nitroglycerin / Q000008:administration & dosage / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D010417:Pentaerythritol Tetranitrate / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D013482:Superoxide Dismutase / Q000172:deficiency* / Q000235:genetics; D014664:Vasodilation; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
D016166:Free Radical Scavengers; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014665:Vasodilator Agents; D010417:Pentaerythritol Tetranitrate; D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; C515029:ALDH2 protein, mouse; D000444:Aldehyde Dehydrogenase; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D005996:Nitroglycerin; D000109:Acetylcholine; D001663:Bilirubin