Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 2011 Sep 20;108(38):15792-7. doi: 10.1073/pnas.1111331108. Epub 2011 Sep 6.
Nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) are synthesized within cardiac myocytes and play key roles in modulating cardiovascular signaling. Cardiac myocytes contain both the endothelial (eNOS) and neuronal (nNOS) NO synthases, but the differential roles of these NOS isoforms and the interplay of reactive oxygen species and reactive nitrogen species in cardiac signaling pathways are poorly understood. Using a recently developed NO chemical sensor [Cu(2)(FL2E)] to study adult cardiac myocytes from wild-type, eNOS(null), and nNOS(null) mice, we discovered that physiological concentrations of H(2)O(2) activate eNOS but not nNOS. H(2)O(2)-stimulated eNOS activation depends on phosphorylation of both the AMP-activated protein kinase and kinase Akt, and leads to the robust phosphorylation of eNOS. Cardiac myocytes isolated from mice infected with lentivirus expressing the recently developed H(2)O(2) biosensor HyPer2 show marked H(2)O(2) synthesis when stimulated by angiotensin II, but not following β-adrenergic receptor activation. We discovered that the angiotensin-II-promoted increase in cardiac myocyte contractility is dependent on H(2)O(2), whereas β-adrenergic contractile responses occur independently of H(2)O(2) signaling. These studies establish differential roles for H(2)O(2) in control of cardiac contractility and receptor-dependent NOS activation in the heart, and they identify new points for modulation of NO signaling responses by oxidant stress.
一氧化氮（NO）和过氧化氢（H₂O₂）在心肌细胞内合成，在调节心血管信号中发挥关键作用。心肌细胞包含内皮型（eNOS）和神经元型（nNOS）一氧化氮合酶，但这些 NOS 同工型的差异作用以及活性氧和活性氮物种在心脏信号通路中的相互作用仍知之甚少。使用最近开发的一氧化氮化学传感器 [Cu₂（FL2E）] 研究来自野生型、eNOS（null）和 nNOS（null）小鼠的成年心肌细胞，我们发现生理浓度的 H₂O₂激活 eNOS 但不激活 nNOS。H₂O₂刺激的 eNOS 激活依赖于 AMP 激活蛋白激酶和蛋白激酶 Akt 的磷酸化，并导致 eNOS 的强烈磷酸化。用表达最近开发的 H₂O₂生物传感器 HyPer2 的慢病毒感染的小鼠分离的心肌细胞在受到血管紧张素 II 刺激时显示出明显的 H₂O₂合成，但在β-肾上腺素能受体激活后没有。我们发现，血管紧张素 II 促进心肌细胞收缩力的增加依赖于 H₂O₂，而β-肾上腺素能收缩反应独立于 H₂O₂信号。这些研究确立了 H₂O₂在控制心脏收缩力和受体依赖性 NOS 激活方面的差异作用，并确定了氧化应激调节 NO 信号反应的新靶点。
