Department of Medicine II (Gastroenterology and Hepatology), University of Munich-Grosshadern, Munich, Germany.
Shock. 2010 Apr;33(4):412-8. doi: 10.1097/SHK.0b013e3181b85934.
This study aimed to investigate the effects of reactive oxygen species on the hepatic macrophages, the Kupffer cells (KC), and to identify the relevant targets of vasoconstrictors involved in the regulation of intrahepatic microcirculation and therefore portal pressure. The effects of hydrogen peroxide (H2O2), xanthine/xanthine oxidase or a thromboxane (TX) analogue (U46619; 0.1 microM) were tested in sham-operated and fibrotic livers (bile duct ligation over 4 weeks) during isolated rat liver perfusion and in vivo with or without additional KC blockade (gadolinium chloride, 10 mg kg(-1) body weight, 48 and 24 h, i.p.). To investigate downstream mechanisms, a TXA2 antagonist (BM 13.177; 20 microM) or a Rho kinase inhibitor (Y27632; 10 microM) was infused additionally. TXB2 efflux was measured by enzyme-linked immunosorbent assay. The phosphorylation state of moesin (p-moesin), as indicator for Rho kinase activity, was assessed by Western blot analyses. Portal pressure was dose-dependently increased by H2O2 (maximum, 0.5 mM) and, to a lower extent, by xanthine/xanthine oxidase together with catalase. The portal pressure increase by H2O2 was attenuated by previous KC blockade. TXA2 efflux increased after H2O2 infusion and was reduced by KC blockade. The TXA2 antagonist counteracted the H2O2-induced increase in portal pressure. The Rho kinase inhibitor attenuated portal pressure increase after TXA2 analogue or H2O2 infusion. Hepatic levels of p-moesin were increased after H2O2 infusion. Reactive oxygen species increased portal pressure via stimulation of TXA2 production by KCs and a subsequent Rho kinase-dependent contraction of the intrahepatic vasculature. In conclusion, the KCs that are well known to produce H2O2 could also be activated by H2O2. This vicious cycle may best be interrupted at the earliest time point.
本研究旨在探讨活性氧对肝巨噬细胞（枯否细胞）的影响，并确定参与调节肝内微循环和门静脉压的缩血管物质的相关靶点。在离体大鼠肝灌注和体内实验中，检测了过氧化氢（H2O2）、黄嘌呤/黄嘌呤氧化酶或血栓烷（TX）类似物（U46619；0.1μM）在假手术和纤维化肝脏（胆管结扎 4 周）中的作用，同时进行或不进行额外的 KC 阻断（氯化钆，10mgkg(-1)体重，腹腔内注射 48 和 24 小时）。为了研究下游机制，另外输注了 TXA2 拮抗剂（BM 13.177；20μM）或 Rho 激酶抑制剂（Y27632；10μM）。通过酶联免疫吸附试验测量 TXB2 外排。通过 Western blot 分析评估 moesin 的磷酸化状态（p-moesin），作为 Rho 激酶活性的指标。H2O2（最大浓度为 0.5mM）和黄嘌呤/黄嘌呤氧化酶与过氧化氢酶一起剂量依赖性地增加门静脉压力。H2O2 引起的门静脉压力升高可被 KC 阻断预先减轻。H2O2 输注后 TXA2 外排量增加，KC 阻断后减少。TXA2 拮抗剂可拮抗 H2O2 诱导的门静脉压力升高。Rho 激酶抑制剂可减轻 TXA2 类似物或 H2O2 输注后门静脉压力升高。H2O2 输注后肝内 p-moesin 水平增加。活性氧通过 KC 产生 TXA2 的刺激和随后的 Rho 激酶依赖性肝内血管收缩来增加门静脉压力。总之，众所周知的产生 H2O2 的 KC 也可被 H2O2 激活。这种恶性循环可能在最早的时间点被打断。
