Increased inducible nitric oxide synthase and arginase II expression in heart failure: no net nitrite/nitrate production and protein S-nitrosylation.
Our objective was to address the balance of inducible nitric oxide (NO) synthase (iNOS) and arginase and their contribution to contractile dysfunction in heart failure (HF). Excessive NO formation is thought to contribute to contractile dysfunction; in macrophages, increased iNOS expression is associated with increased arginase expression, which competes with iNOS for arginine. With substrate limitation, iNOS may become uncoupled and produce reactive oxygen species (ROS). In rabbits, HF was induced by left ventricular (LV) pacing (400 beats/min) for 3 wk. iNOS mRNA [quantitative real-time PCR (qRT-PCR)] and protein expression (confocal microscopy) were detected, and arginase II expression was quantified with Western blot; serum arginine and myocardial nitrite and nitrate concentrations were determined by chemiluminescence, and protein S-nitrosylation with Western blot. Superoxide anions were quantified with dihydroethidine staining. HF rabbits had increased LV end-diastolic diameter [20.0 + or - 0.5 (SE) vs. 17.2 + or - 0.3 mm in sham] and decreased systolic fractional shortening (11.1 + or - 1.4 vs. 30.6 + or - 0.7% in sham; both P < 0.05). Myocardial iNOS mRNA and protein expression were increased, however, not associated with increased myocardial nitrite or nitrate concentrations or protein S-nitrosylation. The serum arginine concentration was decreased (124.3 + or - 5.6 vs. 155.4 + or - 12.0 micromol/l in sham; P < 0.05) at a time when cardiac arginase II expression was increased (0.06 + or - 0.01 vs. 0.02 + or - 0.01 arbitrary units in sham; P < 0.05). Inhibition of iNOS with 1400W attenuated superoxide anion formation and contractile dysfunction in failing hearts. Concomitant increases in iNOS and arginase expression result in unchanged NO species and protein S-nitrosylation; with substrate limitation, uncoupled iNOS produces superoxide anions and contributes to contractile dysfunction.
Heusch
Philipp
P
Institute for Pathophysiology, Univ. of Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany.
Aker
Stephanie
S
Boengler
Kerstin
K
Deindl
Elisabeth
E
van de Sand
Anita
A
Klein
Kristina
K
Rassaf
Tienush
T
Konietzka
Ina
I
Sewell
Adrian
A
Menazza
Sara
S
Canton
Marcella
M
Heusch
Gerd
G
Di Lisa
Fabio
F
Schulz
Rainer
R
D000818:Animals; D001119:Arginase / Q000378:metabolism*; D001120:Arginine / Q000097:blood; D015153:Blotting, Western; D002304:Cardiac Pacing, Artificial; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006333:Heart Failure / Q000201:enzymology* / Q000209:etiology / Q000503:physiopathology; D006339:Heart Rate; D007097:Imines / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology*; D009566:Nitrates / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013318:Stroke Volume; D013481:Superoxides / Q000378:metabolism; D015854:Up-Regulation; D016277:Ventricular Function, Left / Q000187:drug effects
D004791:Enzyme Inhibitors; D007097:Imines; C496401:N-((3-(aminomethyl)phenyl)methyl)ethanimidamide; D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; D013481:Superoxides; D001120:Arginine; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D001119:Arginase