Mobilization of low-molecular-weight iron and peroxidative damage during ischemia and reoxygenation of the rat liver.

Third Department of Surgery, Tokyo Women's Medical College, Japan.
Transplantation Proceedings (Impact Factor: 0.95). 05/1994; 26(2):918-21.
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    ABSTRACT: To evaluate whether desferrioxamine decreases ischemia and perfusion injury aggravated by cold storage (CS) in a rat liver perfusion model. Isolated rat livers were kept in CS in University of Wisconsin Solution for 20 h at 4 °C, then exposed to 25 min of warm ischemia (WI) at 37 °C followed by 2 h of warm perfusion (WP) at 37 °C with oxygenated (95% oxygen and 5% carbon dioxide) Krebs-Henseleit buffer. Desferrioxamine (DFO), an iron chelator, was added at different stages of storage, ischemia and perfusion: in CS only, in WI only, in WP only, in WI and perfusion, or in all stages. Effluent samples were collected after CS and after WI. Perfusate samples and bile were collected every 30 min (0, 0.5, 1, 1.5 and 2 h) during liver perfusion. Cellular injury was assessed by the determination of lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) in the effluent and perfusate samples. Total iron was analysed in the perfusate samples. After WP, the liver was collected for the determination of liver swelling (wet to dry ratio) and liver morphological examination (hematoxylin and eosin staining). Increased CS time caused increased liver dysfunction during WP. After 2 h of WP, liver injury was indicated by increased release of AST (0.5 h CS: 9.4 ± 2.2 U/g liver vs 20 h CS: 45.9 ± 10.8 U/g liver, P < 0.05) and LDH (0.5 h CS: 59 ± 14 U/g liver vs 20 h CS: 297 ± 71 U/g liver, P < 0.05). There was an associated increase in iron release into the perfusate (0.5 h CS: 0.11 ± 0.03 μmoL/g liver vs 20 h CS: 0.58 ± 0.10 μmoL/g liver, P < 0.05) and reduction in bile flow (0.5 h CS: 194 ± 12 μL/g vs 20 h CS: 71 ± 8 μL/g liver, P < 0.05). When DFO was added during WI and WP following 20 h of CS, release of iron into the perfusate was decreased (DFO absent 0.58 ± 0.10 μmoL/g liver vs DFO present 0.31 ± 0.06 μmoL/g liver, P < 0.05), and liver function substantially improved with decreased release of AST (DFO absent 45.9 ± 10.8 U/g liver vs DFO present 8.1 ± 0.9 U/g liver, P < 0.05) and LDH (DFO absent 297 ± 71 U/g liver vs DFO present 56 ± 7 U/g liver, P < 0.05), and increased bile flow (DFO absent 71 ± 8 μL/g liver vs DFO present 237 ± 36 μL/g liver, P < 0.05). DFO was also shown to improve liver morphology after WP. Cellular injury (the release of LDH and AST) was significantly reduced with the addition of DFO in CS medium but to a lesser extent compared to the addition of DFO in WP or WI and perfusion. There was no effect on liver swelling or bile flow when DFO was only added to the CS medium. DFO added during WI and perfusion decreased liver perfusion injury aggravated by extended CS.
    World Journal of Gastroenterology 02/2013; 19(5):673-81. · 2.55 Impact Factor
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    ABSTRACT: Both Atp7b (Wilson disease gene) and Atp7a (Menkes disease gene) have been reported to be trafficked by copper. Atp7b is trafficked to the bile duct canaliculi and Atp7a to the plasma membrane. Whether or not liver ischemia or ischemia-reperfusion modulates Atp7b expression and trafficking has not been reported. In this study, we report for the first time that the multi-specific metal transporter Atp7b is significantly induced and trafficked by both liver ischemia alone and liver ischemia-reperfusion, as judged by immunohistochemistry and Western blot analyses. Although hepatocytes also stained for Atp7b, localized intense staining of Atp7b was found on bile duct canaliculi. Inductive coupled plasma-mass spectrometry analysis of bile copper, iron, zinc, and manganese found a corresponding significant increase in biliary iron. In our attempt to determine if the increased biliary iron transport observed may be a result of altered bile flow, lysosomal trafficking, or glutathione biliary transport, we measured bile flow, bile acid phosphatase activity, and glutathione content. No significant difference was found in bile flow, bile acid phosphatase activity, and glutathione, between control livers and livers subjected to ischemia-reperfusion. Thus, we conclude that liver ischemia and ischemia-reperfusion induction and trafficking Atp7b to the bile duct canaliculi may contribute to preferential iron transport into bile.
    Biological Trace Element Research 05/2008; 122(1):26-41. · 1.31 Impact Factor
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    ABSTRACT: Oxidative stress is believed to accompany reperfusion and to mediate dysfunction of the liver after traumatic-hemorrhagic shock (THS). Recently, endoplasmic reticulum (ER) stress has been suggested as an additional factor. This study investigated whether reperfusion after THS leads to increased oxidative and/or ER stress in the liver. In a rat model, including laparotomy, bleeding until decompensation, followed by inadequate or adequate reperfusion phase, three time points were investigated: 40 min, 3 h, and 18 h after shock. The reactive oxygen and nitrogen species and its scavenging capacity (superoxide dismutase 2), the nitrotyrosine formation in proteins, and the lipid peroxidation together with the status of endogenous antioxidants (alpha-tocopherylquinone-alpha-tocopherol ratio) were investigated as markers for oxidative or nitrosylative stress. Mitochondrial function and cytochrome P450 isoform 1A1 activity were analyzed as representatives for hepatocyte function. Activation of the inositol-requiring enzyme 1/X-box binding protein pathway and up-regulation of the 78-kDa glucose-regulated protein were recorded as ER stress markers. Plasma levels of alanine aminotransferase and Bax/Bcl-XL messenger RNA (mRNA) ratio were used as indicators for hepatocyte damage and apoptosis induction. Oxidative or nitrosylative stress markers or representatives of hepatocyte function were unchanged during and short after reperfusion (40 min, 3 h after shock). In contrast, ER stress markers were elevated and paralleled those of hepatocyte damage. Incidence for sustained ER stress and subsequent apoptosis induction were found at 18 h after shock. Thus, THS or reperfusion induces early and persistent ER stress of the liver, independent of oxidative or nitrosylative stress. Although ER stress was not associated with depressed hepatocyte function, it may act as an early trigger of protracted cell death, thereby contributing to delayed organ failure after THS.
    Shock (Augusta, Ga.) 07/2009; 33(3):289-98. · 2.87 Impact Factor