The response of the hepatocyte to ischemia

BACKGROUND: Ischemia-reperfusion (I/R) injury associated with hepatic resections and liver transplantation remains a serious complication in clinical practice, in spite of several attempts to solve the problem. AIMS: To evaluate the response of the hepatocyte to ischemia METHODS: Published data are thus revised. RESULTS: The response of the hepatocyte to ischemia is based on the sensitivity of hepatocytes to different types of ischemia, the kind of cell death of the hepatocyte when it is subjected to ischemia, and on the response of the hepatocyte to the different times and extents of ischemia. Clinical factors including starvation, graft, age, and hepatic steatosis, all of which contribute to enhancing liver susceptibility to ischemia/reperfusion injury. CONCLUSION: Ischemic preconditioning, based on the induction of a brief ischemia to the liver prior to a prolonged ischemia, has been applied in tumor hepatic resections for reducing hepatic I/R injury and recent clinical studies suggest that this surgical strategy could be appropriate for liver transplantation

Fructose-1,6-biphosphate in rat intestinal preconditioning: involvement of nitric oxide

BACKGROUND AND AIMS—Inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by nitric oxide (NO) in intestinal preconditioning could modify the rate of formation of glycolytic intermediates. Fructose-1,6-biphosphate (F16BP) is a glycolytic intermediate that protects tissue from ischaemia/reperfusion injury. We evaluated if F16BP may be endogenously accumulated as a consequence of GAPDH inhibition by NO during intestinal preconditioning in rats.
METHODS—We assessed: (1) effect of preconditioning on F16BP content; (2) effect of NO on GAPDH activity before and during sustained ischaemia; and (3) protective effect of F16BP in control, ischaemic, and preconditioned animals with or without administration of N-nitro-L-arginine methyl ester (L-NAME), NO donor, or F16BP.
RESULTS—Preconditioned rats showed a significant transient decrease in GAPDH activity and also maintained basal F16BP levels longer than ischaemic rats. L-NAME administration to preconditioned rats reversed these effects. F16BP administration to ischaemic rats decreased protein release in the perfusate. Administration of F16BP to L-NAME treated rats attenuated the harmful effect of L-NAME.
CONCLUSIONS—Our study indicates that F16BP may be endogenously accumulated in preconditioned rats as a consequence of inhibition of GAPDH by NO, and this may contribute to the protection observed in intestinal preconditioning.


Keywords: fructose-1,6-biphosphate; glyceraldehyde- 3-phosphate dehydrogenase; intestinal preconditioning; ischaemia/reperfusion injury; nitric oxid

Up regulation of IL-6 by ischemic preconditioning in normal and fatty rat livers: association with reduction of oxidative stress

We analyzed the role of IL-6 in the protection that ischemic preconditioning (IP) exerts against hepatic ischemia reperfusion-mediated (I/R) oxidative damage, particularly in fatty livers. IP-related IL-6 up-regulation during reperfusion in steatotic and non-steatotic livers was correlated with reduced indexes of liver damage, as also demonstrated by pharmacol. modulation of IL-6. IP activated NF-kB and HSF during ischemia (Isc), whereas AP-1 activity was unaffected. IP blunted the activation of STAT3 and stress-responsive genes, such as NF-kB, AP-1 and heme oxygenase (HO-1) during reperfusion. The role of reduced oxidative stress in hepatoprotection of fatty livers was further demonstrated by the fact that: (i) IP prevented the decrease of glutathione levels and the increase of lipid peroxidn.; (ii) the anti-oxidant GSH-ester prevented lipid peroxidn. and necrosis. In conclusion, IP modulates the activity of transcription factors and triggers IL-6 prodn.; this may prevent hepatic I/R damage in a oxidative stress-dependent way, particularly in fatty livers

HIF is under control of nitric oxide in normoxic fatty liver graft reperfusion injury

AIM: Here we examine the relevance of hypoxia inducible factor (HIF-1) and nitric oxide (NO) on the preservation of fatty liver against cold ischemia-reperfusion injury (IRI). METHODS: We used an isolated perfused rat liver model and we evaluated HIF-1α in steatotic and non-steatotic livers preserved for 24 hours at 4ºC in UW and IGL-1 solutions and then subjected to 2 hours of normothermic reperfusion. After normoxic reperfusion, AST/ALT, bile production, bromosulfophthalein clearance, as well as HIF-1α and NO (eNOS activity and nitrites/nitrates) were also measured. Other factors associated with the higher susceptibility of steatotic livers to IRI as mitochondrial damage (GLDH) and vascular resistance were evaluated. RESULTS: A significant increase of HIF-1α was evidenced in steatotic and non-steatotic livers preserved in IGL-1 after cold storage. Livers preserved in IGL-1 showed a significant prevention of liver injury and an amelioration of liver function parameters. These benefits were enhanced by the addition of trimetazidine (an anti-ischemic drug) to IGL-1 solution which induces NO and eNOS activation. In normoxic reperfusion, the presence of NO favours the HIF-1α accumulation, promoting also the activation of other cytoprotective genes, as heme-oxygenase-1. CONCLUSION: We evidenced the relevance of the HIF-1α/NO system for fatty liver preservation, especially when IGL-1 solution is used

P-selectin upregulation in bleomycin induced lung injury in rats: effect of N-acetyl-L-cysteine

Background: A number of adhesion molecules are involved in the process of neutrophil infiltration into the lung. P-selectin is one of these neutrophil-endothelial cell adhesion molecules. A study was undertaken to examine the involvement of P-selectin in the development of bleomycin induced inflammation and the ability of N-acetyl-L-cysteine to reduce the potential expression of this selectin in rats. Methods: N-acetyl-L-cysteine (3 mmol/kg po) was administered daily for seven days prior to bleomycin administration (2.5 U/kg). The kinetics of P-selectin expression and the effect of N-acetyl-L-cysteine after bleomycin treatment were measured using radiolabelled antibodies. P-selectin localisation was evaluated by immunohistochemistry and neutrophil infiltration was assessed by myeloperoxidase activity. Results: Bleomycin administration resulted in an upregulation of P-selectin at 1 hour, returning to baseline at 3 hours. Myeloperoxidase activity showed a significant increase at 6 hours after bleomycin administration that lasted for 3 days. N-acetyl-L-cysteine treatment completely prevented these increases. Conclusion: Upregulation of P-selectin in the lung is associated with neutrophil recruitment in response to bleomycin. The beneficial effect of N-acetyl-L-cysteine on bleomycin induced lung injury may be explained in part by the prevention of neutrophil recruitment in the inflammatory stage of the disease

Graft Protection Against Cold Ischemia Preservation: An Institute George Lopez 1 and Histidine-tryptophan-ketoglutarate Solution Appraisal

Cold storage of organs in preservation solutions, such as Institute George Lopez 1 (IGL-1) or histidine-tryptophan-ketoglutarate (HTK), is a mandatory step for organ transplantation. This preservation leads to an ischemic injury that affects the outcome of the organ. This article studies the liver graft eluate after organ recovery using IGL-1 or HTK solutions. We explore the influence of the volume used for washing out the liver and the consequences in the graft preservation when both solutions are used. Livers were washed out with different volumes of HTK and IGL-1 according to manufacturers' instructions and then preserved in both solutions for 24 hours at 4°C. Tissue and eluates were collected for subsequent analyses. We measured transaminases (aspartate aminotransferase and alanine aminotransferase), histology by hematoxylin/eosin staining, and red blood cell and hemoglobin counts, respectively. After washing out and cold storage, the IGL-1 processed livers showed better preservation than those with HTK solution; however, in this latter case, an important accumulation of erythrocytes was found when compared to IGL-1. These data were consistent with the higher hemoglobin and red blood cell counts observed for IGL-1 eluates after 24 hours. The volume used for washing out the organ depends on the composition and properties of the organ preservation solutions (ie, IGL-1 and HTK); this is an important factor for the graft cold preservation. The total volume used for washing out the graft should be considered because it has a direct impact on the total cost for clinical transplantations