Hara Yuzuru, Teramoto Kenichi, Ishidate Kozo, Arii Shigeki
Department of Surgery, School of Medicine, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
Surgery. 2006 Mar;139(3):377-84. doi: 10.1016/j.surg.2005.08.019.
Tetrahydrobiopterin (BH(4)) is a key coenzyme of nitric oxide synthase (NOS), which is associated with a cytoprotective function in various ischemia-reperfusion (I/R) injury models. There have been a few reports on the efficacy of BH(4) in the treatment of I/R injury in other organs; therefore, the aim of this study was to investigate the effect of BH(4) related with NOS reaction in hepatic I/R injury.
A model of 70% liver I/R injury with a 100-minute ischemic time was created in rats, and the non-ischemic lobes were then resected. The rats were given BH(4) (BH(4) group) or saline solution (saline group) before reperfusion. The specific inducible NOS blocker 1400W was used to evaluate the effect of endogenous inducible NOS in the I/R hepatic injury. Survival, nitric oxide products (nitrate and nitrite), NOS expression, and nitrotyrosine (ie, the peroxynitrite product) were measured after reperfusion.
On day 7, the survival rate was 62.5% in the BH(4) group, as opposed to 14.3% in the saline group (P = .0004); 1400W administration to the BH(4) group decreased the survival rate to 0% (P = .003). BH(4) prevented the significant increase in total bilirubin levels (P < .01) after 12-hour reperfusion. The increases in serum alanine transaminase levels (after 3 hours and 12 hours of reperfusion) were significantly (P < .01) attenuated in the BH(4) group. BH(4) increased the nitrate/nitrite concentrations in liver tissue (P < .05) and reduced nitrotyrosine production, and the protein assay showed that BH(4) increased inducible NOS and endothelial NOS expression. Histologic examination of the liver revealed that BH(4) mitigated the damage that was caused by liver I/R.
Exogenous BH(4) increased nitric oxide production, which attenuated the hepatic I/R injury.
四氢生物蝶呤（BH₄）是一氧化氮合酶（NOS）的关键辅酶，在多种缺血再灌注（I/R）损伤模型中具有细胞保护功能。关于BH₄在治疗其他器官I/R损伤方面的疗效已有一些报道；因此，本研究的目的是探讨与NOS反应相关的BH₄在肝脏I/R损伤中的作用。
在大鼠中建立缺血100分钟的70%肝脏I/R损伤模型，然后切除非缺血叶。在再灌注前给大鼠注射BH₄（BH₄组）或生理盐水（生理盐水组）。使用特异性诱导型NOS阻滞剂1400W评估内源性诱导型NOS在I/R肝损伤中的作用。再灌注后测量存活率、一氧化氮产物（硝酸盐和亚硝酸盐）、NOS表达和硝基酪氨酸（即过氧亚硝酸盐产物）。
在第7天，BH₄组的存活率为62.5%，而生理盐水组为14.3%（P = 0.0004）；给BH₄组注射1400W后存活率降至0%（P = 0.003）。BH₄可防止再灌注12小时后总胆红素水平的显著升高（P < 0.01）。BH₄组血清丙氨酸转氨酶水平在再灌注3小时和12小时后的升高显著（P < 0.01）减弱。BH₄增加了肝组织中硝酸盐/亚硝酸盐浓度（P < 0.05）并减少了硝基酪氨酸的产生，蛋白质检测显示BH₄增加了诱导型NOS和内皮型NOS的表达。肝脏组织学检查显示BH₄减轻了肝脏I/R引起的损伤。
外源性BH₄增加了一氧化氮的产生，从而减轻了肝脏I/R损伤。
