Institute for Pathophysiology, Univ. of Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany.
Am J Physiol Heart Circ Physiol. 2010 Aug;299(2):H446-53. doi: 10.1152/ajpheart.01034.2009. Epub 2010 May 28.
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.
我们的目标是解决诱导型一氧化氮合酶 (iNOS) 和精氨酸酶的平衡及其对心力衰竭 (HF) 收缩功能障碍的贡献。过度的 NO 形成被认为有助于收缩功能障碍; 在巨噬细胞中，iNOS 表达的增加与精氨酸酶表达的增加相关，后者与 iNOS 竞争精氨酸。在底物限制的情况下，iNOS 可能会失去偶联并产生活性氧 (ROS)。在兔子中，通过左心室 (LV) 起搏 (400 次/分钟) 诱导 HF 3 周。通过定量实时 PCR (qRT-PCR) 检测 iNOS mRNA 和蛋白表达 (共聚焦显微镜)，并通过 Western blot 定量测定精氨酸酶 II 的表达; 血清精氨酸和心肌亚硝酸盐和硝酸盐浓度通过化学发光法测定，蛋白 S-亚硝基化通过 Western blot 测定。超氧阴离子通过二氢乙啶染色定量。HF 兔的 LV 舒张末期直径增加[20.0 + 或 - 0.5(SE) 与假手术组的 17.2 + 或 - 0.3mm 相比]，收缩分数缩短[11.1 + 或 - 1.4 与假手术组的 30.6 + 或 - 0.7%相比; 均 P < 0.05]。心肌 iNOS mRNA 和蛋白表达增加，但与心肌亚硝酸盐或硝酸盐浓度或蛋白 S-亚硝基化增加无关。血清精氨酸浓度降低(124.3 + 或 - 5.6 与假手术组的 155.4 + 或 - 12.0 微摩尔/升相比; P < 0.05)，而此时心脏精氨酸酶 II 表达增加(0.06 + 或 - 0.01 与假手术组的 0.02 + 或 - 0.01 任意单位相比; P < 0.05)。用 1400W 抑制 iNOS 可减轻衰竭心脏中超氧阴离子的形成和收缩功能障碍。iNOS 和精氨酸酶表达的同时增加导致 NO 物种和蛋白 S-亚硝基化不变; 在底物限制的情况下，失偶联的 iNOS 产生超氧阴离子并导致收缩功能障碍。
