Deaciuc I V, D'Souza N B, Sarphie T G, Schmidt J, Hill D B, McClain C J
Department of Internal Medicine, Albert B. Chandler Medical Center, University of Kentucky, Lexington, USA.
J Hepatol. 1999 Feb;30(2):213-21. doi: 10.1016/s0168-8278(99)80064-6.
BACKGROUND/AIMS: Functional and morphological alterations of the hepatic sinusoidal endothelial cell occur in several models of experimental liver injury and in clinical settings. The causes of these alterations are multiple. The aim of this study was to test the hypothesis that the early functional impairment and morphological alterations of the sinusoidal endothelial cell and hepatic sinusoid associated with liver injury are mediated by free radical species, such as superoxide anion and nitric oxide.
Isolated rat livers were perfused by recirculation with hemoglobin-free, Krebs-Henseleit bicarbonate buffer and presented with a source of superoxide anion (xanthine oxidase+hypoxanthine) or nitric oxide (S-nitroso-N-acetyl penicillamine). Hyaluronan uptake (an index of sinusoidal endothelial cell scavenging function), thiobarbituric acid-reactive substances content of the tissue (a marker of lipid peroxidation), reduced and oxidized glutathione (a marker of the thiol system oxidation/reduction state), lactate dehydrogenase and alanine aminotransferase activities (markers of cytolysis), as well as scanning and transmission electron microscopic appearance of the sinusoid were evaluated.
At the high concentrations used, both free radical generating systems suppressed hyaluronan uptake, increased malondialdehyde content of the tissue, enhanced the release of both liver enzymes, decreased the total glutathione content of the liver, and altered the ratio of reduced/oxidized glutathione. Both free radical species induced dose-dependent morphological alterations of the sinusoid, consisting of the appearance of large gaps replacing the sieve-plated fenestration.
The free radical species-induced functional impairment and morphological alterations of the liver sinusoid, presented in this study, closely resemble the early in vivo changes associated with liver injury under a variety of conditions, such as preservation and reperfusion, or administration of hepatotoxicants such as D-galactosamine, Gram-negative bacterial lipopolysaccharides, acetaminophen, alcohol and others. Therefore, we suggest that early liver sinusoid injury, observed under these conditions, can be attributed to the action of free radicals, such as superoxide anion and nitric oxide.
背景/目的：肝窦内皮细胞的功能和形态改变出现在多种实验性肝损伤模型及临床环境中。这些改变的原因是多方面的。本研究的目的是验证以下假说：与肝损伤相关的肝窦内皮细胞和肝血窦的早期功能损害及形态改变是由超氧阴离子和一氧化氮等自由基介导的。
用无血红蛋白的 Krebs-Henseleit 碳酸氢盐缓冲液对分离的大鼠肝脏进行再循环灌注，并给予超氧阴离子源（黄嘌呤氧化酶+次黄嘌呤）或一氧化氮源（S-亚硝基-N-乙酰青霉胺）。评估透明质酸摄取（肝窦内皮细胞清除功能的指标）、组织中硫代巴比妥酸反应性物质含量（脂质过氧化的标志物）、还原型和氧化型谷胱甘肽（硫醇系统氧化/还原状态的标志物）、乳酸脱氢酶和丙氨酸氨基转移酶活性（细胞溶解的标志物），以及肝血窦的扫描和透射电子显微镜外观。
在所用的高浓度下，两种自由基生成系统均抑制透明质酸摄取，增加组织中丙二醛含量，增强两种肝酶的释放，降低肝脏总谷胱甘肽含量，并改变还原型/氧化型谷胱甘肽的比例。两种自由基均诱导肝血窦出现剂量依赖性形态改变，表现为出现大的间隙取代筛板状窗孔。
本研究中自由基诱导的肝血窦功能损害和形态改变与多种情况下肝损伤相关的早期体内变化非常相似，如保存和再灌注，或给予 D-半乳糖胺、革兰氏阴性菌脂多糖、对乙酰氨基酚、酒精等肝毒性物质。因此，我们认为在这些情况下观察到的早期肝血窦损伤可归因于超氧阴离子和一氧化氮等自由基的作用。
