Divison of Cardiology, Department of Medicine, and Divison of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, 171 76 Stockholm, Sweden.
Proc Natl Acad Sci U S A. 2013 Sep 10;110(37):15049-54. doi: 10.1073/pnas.1307058110. Epub 2013 Aug 26.
The theory that red blood cells (RBCs) generate and release nitric oxide (NO)-like bioactivity has gained considerable interest. However, it remains unclear whether it can be produced by endothelial NO synthase (eNOS), which is present in RBCs, and whether NO can escape scavenging by hemoglobin. The aim of this study was to test the hypothesis that arginase reciprocally controls NO formation in RBCs by competition with eNOS for their common substrate arginine and that RBC-derived NO is functionally active following arginase blockade. We show that rodent and human RBCs contain functional arginase 1 and that pharmacological inhibition of arginase increases export of eNOS-derived nitrogen oxides from RBCs under basal conditions. The functional importance was tested in an ex vivo model of myocardial ischemia-reperfusion injury. Inhibitors of arginase significantly improved postischemic functional recovery in rat hearts if administered in whole blood or with RBCs in plasma. By contrast, arginase inhibition did not improve postischemic recovery when administered with buffer solution or plasma alone. The protective effect of arginase inhibition was lost in the presence of a NOS inhibitor. Moreover, hearts from eNOS(-/-) mice were protected when the arginase inhibitor was given with blood from wild-type donors. In contrast, when hearts from wild-type mice were given blood from eNOS(-/-) mice, the arginase inhibitor failed to protect against ischemia-reperfusion. These results strongly support the notion that RBCs contain functional eNOS and release NO-like bioactivity. This process is under tight control by arginase 1 and is of functional importance during ischemia-reperfusion.
红细胞（RBC）产生并释放类似一氧化氮（NO）的生物活性这一理论已经引起了相当大的兴趣。然而，目前尚不清楚它是否可以由存在于 RBC 中的内皮型一氧化氮合酶（eNOS）产生，以及 NO 是否可以逃脱血红蛋白的清除。本研究旨在检验以下假设：精氨酸酶通过与 eNOS 竞争其共同底物精氨酸来反向控制 RBC 中 NO 的形成，并且 RBC 衍生的 NO 在精氨酸酶阻断后具有功能活性。我们表明，啮齿动物和人类 RBC 含有功能性精氨酸酶 1，并且药理学抑制精氨酸酶会增加 RBC 中 eNOS 衍生的氮氧化物在基础条件下的输出。在心肌缺血再灌注损伤的离体模型中测试了其功能重要性。如果在全血中或在血浆中与 RBC 一起给予精氨酸酶抑制剂，可显著改善大鼠心脏缺血后的功能恢复。相比之下，如果给予缓冲液溶液或仅用血浆，则精氨酸酶抑制不会改善缺血后的恢复。在存在 NOS 抑制剂的情况下，精氨酸酶抑制的保护作用丧失。此外，当给予来自野生型供体的血液时，eNOS（-/-）小鼠的心脏得到了保护。相比之下，当给予来自野生型小鼠的心脏来自 eNOS（-/-）小鼠的血液时，精氨酸酶抑制剂不能防止缺血再灌注。这些结果强烈支持 RBC 含有功能性 eNOS 并释放类似 NO 的生物活性的观点。该过程受精氨酸酶 1 的严格控制，在缺血再灌注期间具有功能重要性。
