Kao Raymond L C, Martin Claudio M, Xenocostas Anargyros, Huang Weixiong, Rui Tao
Department of National Defense, Canadian Forces Health Services, Ottawa, Ontario, Canada.
J Trauma. 2011 Nov;71(5 Suppl 1):S462-7. doi: 10.1097/TA.0b013e318232e7a2.
Sepsis and septic shock remain the major causes of morbidity and mortality in intensive care units. One mechanism that leads to organ failure is microcirculatory dysfunction. Erythropoietin (EPO) is a glycoprotein produced by the kidney that primarily regulates erythropoiesis, but it also can exert hemodynamic, anti-inflammatory, and tissue protective effects. We previously reported that administration of EPO to septic mice improves mouse skeletal muscle capillary perfusion and tissue bioenergetics. The objective of this study was to explore the potential mechanism(s) involved.
Sepsis was induced by intraperitoneal (i.p.) injection of a fecal suspension (12.5 g in 0.5 saline/mouse) in mice. At 18 hours after sepsis induction, a single dose of rHuEPO (400 U/kg) was given to the mice. Mouse capillary perfusion density and nicotinamide adenine dinucleotide (NADH) fluorescence in skeletal muscle were observed using intravital microscopy. Endothelial cells derived from the skeletal muscle were treated with rHuEPO (5 U/mL) and endothelial nitric oxide synthase (eNOS) activation and activity were assessed.
Septic mice had decreased capillary perfusion density and increased tissue NADH fluorescence indicating impaired tissue bioenergetics, whereas animals treated with rHuEPO demonstrated an improvement in capillary perfusion density and decreased skeletal muscle NADH fluorescence. The beneficial effect of rHuEPO did not occur in septic mice treated with l-NAME (an NOS inhibitor, 20 mg/kg) or mice genetically deficient in eNOS. Treatment of endothelial cells with rHuEPO resulted in activation of eNOS as indicated by increased eNOS phosphorylation and NO production.
Our results suggest that eNOS plays an important role in mediating the beneficial effect of rHuEPO on microcirculation in this septic mouse model.
脓毒症和脓毒性休克仍然是重症监护病房发病和死亡的主要原因。导致器官衰竭的一种机制是微循环功能障碍。促红细胞生成素（EPO）是一种由肾脏产生的糖蛋白，主要调节红细胞生成，但它也可发挥血流动力学、抗炎和组织保护作用。我们之前报道，给脓毒症小鼠注射EPO可改善小鼠骨骼肌毛细血管灌注和组织生物能量学。本研究的目的是探索其中潜在的机制。
通过腹腔内（i.p.）注射粪便悬液（每只小鼠0.5ml生理盐水含12.5g）诱导小鼠发生脓毒症。在脓毒症诱导后18小时，给小鼠单次注射重组人促红细胞生成素（rHuEPO，400U/kg）。使用活体显微镜观察小鼠骨骼肌的毛细血管灌注密度和烟酰胺腺嘌呤二核苷酸（NADH）荧光。用rHuEPO（5U/mL）处理来源于骨骼肌的内皮细胞，并评估内皮型一氧化氮合酶（eNOS）的激活和活性。
脓毒症小鼠的毛细血管灌注密度降低，组织NADH荧光增加，表明组织生物能量学受损，而接受rHuEPO治疗的动物毛细血管灌注密度得到改善，骨骼肌NADH荧光降低。rHuEPO的有益作用在接受L-NAME（一种NOS抑制剂，20mg/kg）治疗的脓毒症小鼠或eNOS基因缺陷小鼠中未出现。用rHuEPO处理内皮细胞导致eNOS激活，表现为eNOS磷酸化增加和NO生成增加。
我们的结果表明，在这个脓毒症小鼠模型中，eNOS在介导rHuEPO对微循环的有益作用中起重要作用。
