Hepatic ischemia-reperfusion injury: roles of Ca2+ and other intracellular mediators of impaired bile flow and hepatocyte damage

Role of TRP Channels in Liver-Related Diseases

The liver plays a crucial role in preserving the homeostasis of an entire organism by metabolizing both endogenous and exogenous substances, a process that relies on the harmonious interactions of hepatocytes, hepatic stellate cells (HSCs), Kupffer cells (KCs), and vascular endothelial cells (ECs). The disruption of the liver's normal structure and function by diverse pathogenic factors imposes a significant healthcare burden. At present, most of the treatments for liver disease are palliative in nature, rather than curative or restorative. Transient receptor potential (TRP) channels, which are extensively expressed in the liver, play a crucial role in regulating intracellular cation concentration and serve as the origin or intermediary stage of certain signaling pathways that contribute to liver diseases. This review provides an overview of recent developments in liver disease research, as well as an examination of the expression and function of TRP channels in various liver cell types. Furthermore, we elucidate the molecular mechanism by which TRP channels mediate liver injury, liver fibrosis, and hepatocellular carcinoma (HCC). Ultimately, the present discourse delves into the current state of research and extant issues pertaining to the targeting of TRP channels in the treatment of liver diseases and other ailments. Despite the numerous obstacles encountered, TRP channels persist as an extremely important target for forthcoming clinical interventions aimed at treating liver diseases.

TRPM2-mediated Ca2+ signaling as a potential therapeutic target in cancer treatment: an updated review of its role in survival and proliferation of cancer cells

The transient receptor potential melastatin subfamily member 2 (TRPM2), a thermo and reactive oxygen species (ROS) sensitive Ca²⁺-permeable cation channel has a vital role in surviving the cell as well as defending the adaptability of various cell groups during and after oxidative stress. It shows higher expression in several cancers involving breast, pancreatic, prostate, melanoma, leukemia, and neuroblastoma, indicating it raises the survivability of cancerous cells. In various cancers including gastric cancers, and neuroblastoma, TRPM2 is known to conserve viability, and several underlying mechanisms of action have been proposed. Transcription factors are thought to activate TRPM2 channels, which is essential for cell proliferation and survival. In normal physiological conditions with an optimal expression of TRPM2, mitochondrial ROS is produced in optimal amounts while regulation of antioxidant expression is carried on. Depletion of TRPM2 overexpression or activity has been shown to improve ischemia-reperfusion injury in organ levels, reduce tumor growth and/or viability of various malignant cancers like breast, gastric, pancreatic, prostate, head and neck cancers, melanoma, neuroblastoma, T-cell and acute myelogenous leukemia. This updated and comprehensive review also analyzes the mechanisms by which TRPM2-mediated Ca²⁺ signaling can regulate the growth and survival of different types of cancer cells. Based on the discussion of the available data, it can be concluded that TRPM2 may be a unique therapeutic target in the treatment of several types of cancer. Video Abstract.

How Machine Perfusion Ameliorates Hepatic Ischaemia Reperfusion Injury

The increasing disparity between the number of patients listed for transplantation and the number of suitable organs has led to the increasing use of extended criteria donors (ECDs). ECDs are at increased risk of developing ischaemia reperfusion injury and greater risk of post-transplant complications. Ischaemia reperfusion injury is a major complication of organ transplantation defined as the inflammatory changes seen following the disruption and restoration of blood flow to an organ—it is a multifactorial process with the potential to cause both local and systemic organ failure. The utilisation of machine perfusion under normothermic (37 degrees Celsius) and hypothermic (4–10 degrees Celsius) has proven to be a significant advancement in organ preservation and restoration. One of the key benefits is its ability to optimise suboptimal organs for successful transplantation. This review is focused on examining ischaemia reperfusion injury and how machine perfusion ameliorates the graft’s response to this.

Inhibition of Drp1 SUMOylation by ALR protects the liver from ischemia-reperfusion injury

Hepatic ischemic reperfusion injury (IRI) is a common complication of liver surgery. Although an imbalance between mitochondrial fission and fusion has been identified as the cause of IRI, the detailed mechanism remains unclear. Augmenter of liver regeneration (ALR) was reported to prevent mitochondrial fission by inhibiting dynamin-related protein 1 (Drp1) phosphorylation, contributing partially to its liver protection. Apart from phosphorylation, Drp1 activity is also regulated by small ubiquitin-like modification (SUMOylation), which accelerates mitochondrial fission. This study aimed to investigate whether ALR-mediated protection from hepatic IRI might be associated with an effect on Drp1 SUMOylation. Liver tissues were harvested from both humans and from heterozygous ALR knockout mice, which underwent IRI. The SUMOylation and phosphorylation of Drp1 and their modulation by ALR were investigated. Hepatic Drp1 SUMOylation was significantly increased in human transplanted livers and IRI-livers of mice. ALR-transfection significantly decreased Drp1 SUMOylation, attenuated the IRI-induced mitochondrial fission and preserved mitochondrial stability and function. This study showed that the binding of transcription factor Yin Yang-1 (YY1) to its downstream target gene UBA2, a subunit of SUMO-E1 enzyme heterodimer, was critical to control Drp1 SUMOylation. By interacting with YY1, ALR inhibits its nuclear import and dramatically decreases the transcriptional level of UBA2. Consequently, mitochondrial fission was significantly reduced, and mitochondrial function was maintained. This study showed that the regulation of Drp1 SUMOylation by ALR protects mitochondria from fission, rescuing hepatocytes from IRI-induced apoptosis. These new findings provide a potential target for clinical intervention to reduce the effects of IRI during hepatic surgery.

Investigation of the protective effect of enoxaparin and ticagrelor pretreatment against ischemia-reperfusion injury in rat lung tissue

OBJECTIVES

This study was conducted to reveal the possible protective effects of ticagrelor and enoxaparin pretreatment against ischemia-reperfusion (IR)-induced injury on the lung tissue of a rat model.

METHODS

Wistar albino rats were randomly divided into 4 groups as follows: group-1 (control-sham), group-2 (control-saline+IR), group-3 (ticagrelor+IR), group-4 (enoxaparin+IR). Before the ischemic period, saline, ticagrelor, and enoxaparin were administered to the 2nd-4th groups, respectively. In these groups, IR injury was induced by clamping the aorta infrarenally for 2 h, followed by 4 h of reperfusion except group-1. After the rats were euthanized, the lungs were processed for histological examinations. Paraffin sections were stained with Haematoxylin&Eosin (H&E) for light microscopic observation. Apoptosis was evaluated by caspase-3 immunoreactivity. Data were statistically analyzed using the SPSS software.

RESULTS

In the lung sections stained with H&E, a normal histological structure was observed in group-1, whereas disorganized epithelial cells, hemorrhage, and inflammatory cell infiltration were seen in the alveolar wall in group-2. The histologic structure of the treatment groups was better than that of group-2. Caspase-3(+) apoptotic cells were noticeable in sections of group-2 and were lower in the treatment groups. In group-4, caspase-3 immunostaining was lower than in group-3. In group-2, apoptotic cells were significantly higher than in the other groups (p<0.001).

CONCLUSION

Based on the histological results, we suggested that both therapies ameliorated the detrimental effects of IR. Caspase-3 immunohistochemistry results also revealed that pre-treatment with enoxaparin gave better results in an IR-induced rat injury model. In further studies, other parameters such as ROS and inflammatory gene expressions should be evaluated for accurate results.

Guanine nucleotide-binding protein G(i)α2 aggravates hepatic ischemia-reperfusion injury in mice by regulating MLK3 signaling

Hepatic ischemia-reperfusion (I/R) injury is a major challenge in liver resection and transplantation surgeries. Previous studies have revealed that guanine nucleotide-binding protein G(i)α2 (GNAI2) was involved in the progression of myocardial and cerebral I/R injury, but the role and function of GNAI2 in hepatic I/R have not been elucidated. The hepatocyte-specific GNAI2 knockout (GNAI2hep-/-) mice were generated and subjected to hepatic I/R injury. Primary hepatocytes isolated from GNAI2hep-/- and GNAI2flox/flox mice were cultured and challenged to hypoxia-reoxygenation insult. The specific function of GNAI2 in I/R-triggered hepatic injury and the underlying molecular mechanism were explored by various phenotypic analyses and molecular biology methods. In this study, we demonstrated that hepatic GNAI2 expression was significantly increased in liver transplantation patients and wild-type mice after hepatic I/R. Interestingly, hepatocyte-specific GNAI2 deficiency attenuated I/R-induced liver damage, inflammation cytokine expression, macrophage/neutrophil infiltration, and hepatocyte apoptosis in vivo and in vitro. Mechanistically, up-regulation of GNAI2 phosphorylates mixed-lineage protein kinase 3 (MLK3) through direct binding, which exacerbated hepatic I/R damage via MAPK and NF-κB pathway activation. Furthermore, blocking MLK3 signaling reversed GNAI2-mediated hepatic I/R injury. Our study firstly identifies GNAI2 as a promising target for prevention of hepatic I/R-induced injury and related liver diseases.-Sun, Q., He, Q., Xu, J., Liu, Q., Lu, Y., Zhang, Z., Xu, X., Sun, B. Guanine nucleotide-binding protein G(i)α2 aggravates hepatic ischemia-reperfusion injury in mice by regulating MLK3 signaling.

The effects of oxytocin on penile tissues in experimental priapism model in rats

PURPOSE

This study aimed to demonstrate the effects of oxytocin on penile tissues in ischemia-reperfusion injury developed after priapism.

METHODS

Forty Wistar Albino strain male rats were divided into four groups. The control group (n = 10) was not intervened. In Group 2, a rat model of priapism was constructed and maintained for 1 h. In Group 3, reperfusion was ensured for 30 min following priapism. Rats in Group 4 rats were given oxytocin 30 min before the induction of reperfusion following priapism. All rats were penectomized, and adequate amounts of blood sample were drawn. Inflammation, vasocongestion, desquamation, and edema in penile tissue were scored between 0 and 3 points (0: normal, 1: mild, 2: moderate, 3: severe) to evaluate the severity of tissue damage. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and the levels of malondialdehyde (MDA), and nitric oxide (NO) in blood samples were determined spectrophotometrically.

RESULTS

In histopathological examination, statistically significant positive changes were detected in vasocongestion, inflammation, desquamation, and edema scores in Group 4 than in Group 2 and Group 3 (p < 0.001). Biochemical test results revealed that NO levels were significantly lower in Group 4 than in Group 3 (p < 0.001). Serum GSH-Px activities in Group 4 significantly increased when compared with the other groups 2 and 3 (p = 0.002, p = 0.001, respectively). There was no statistical difference among the groups regarding SOD activities and MDA levels (p > 0.05).

CONCLUSIONS

Oxytocin protected against priapism-induced ischemia-reperfusion injury developed in cavernosal tissue as observed based on histopathological and biochemical evidence. Although this is an experimental study, oxytocin can be thought as an alternative drug in the treatment of priapism.

Effect of HSP27 and Cofilin in the injury of hypoxia/reoxygenation on hepatocyte membrane F-actin microfilaments

Hypoxia-reoxygenation (H/R) injury hepatocyte models were established to simulate the ischemia/reperfusion injury of transplanted organ. Through the study of the molecular mechanism of H/R on the F-actin damage of the liver cytomembrane, the mechanism of F-actin damage induced by ischemia and reperfusion was studied from the level of cell and molecule.The hypoxic environment of cells in vitro was simulated by chemical hypoxia agent CoCl2. Liver cells were detected by MTT, H/R group was subdivided into 3 subgroups: H/R 2, 4, and 6 h. Changes of cell shape and the growth state, apoptosis, ultrastructural changes, and the changes in F-actin microfilament content were observed. Heat shock protein 27 (HSP27), Cofilin, and F-actin gene and protein levels were determined by real-time polymerase chain reaction and western blot assay, respectively.Cells showed circular adherence growth under normal circumstances, while the spindle cells and shedding cells were significantly increased in H/R groups. Apoptosis cells in H/R group were increased significantly with the extension of hypoxia time. The number of endoplasmic reticulum was decreased significantly in the H/R group, the mitochondrion hydropic was degenerated and the glycogen was disappeared. The F-actin fibers in the H/R group were disordered, the morphology of the fibers was obviously decreased, and the fluorescence staining decreased obviously (P < .05). The transcription and expression levels of HSP27, Cofilin, and F-actin were significantly lower than those in the control group (P < .05).These results demonstrate that H/R can affect the correct assembly of F-actin microfilaments and weakens the normal cycle of F-actin microfilaments through inhibiting the protein expression and gene transcription of HSP27 and Cofilin in hepatocytes, thereby changing the skeleton of F-actin microfilaments.

Intermittent ischemia enhances the uptake of indocyanine green to livers subject to ischemia and reperfusion

BACKGROUND AND AIM

Intermittent ischemia is known to promote post perfusion bile flow, and hence recovery of liver function following ischemia reperfusion of the liver. However, the mechanisms involved are not well understood. The aim of this study was to identify the step(s) in the bile acid transport pathway altered by intermittent ischemia.

METHODS

Arat model of segmental hepatic ischemia in which the bilateral median and left lateral lobes were made ischemic by clamping the blood vessels was used. Indocyanine green (ICG), infrared spectroscopy, and compartmental kinetic analysis, were used to indirectly monitor the movement of bile acids across hepatocytes in situ. Rates of bile flow were measured gravimetrically.

RESULTS

In control livers (not subjected to ischemia), the movement of ICG from the blood to bile fluid could be described by a three compartment model comprising the blood, a rapidly-exchangeable compartment, and the hepatocyte cytoplasmic space. In livers subjected to continuous clamping, the rates of ICG uptake to the liver, and outflow from the liver, were greatly reduced compared with those in control livers. Intermittent clamping (three episodes of 15 min clamping) compared with continuous clamping substantially increased the rate of ICG uptake from the blood but had less effect on the rate of ICG outflow from hepatocytes.

CONCLUSIONS

It is concluded that intermittent ischemia promotes post reperfusion bile flow in the early phase of ischemia reperfusion injury principally by enhancing the movement of bile acids from the blood to hepatocytes.

Hepatic cytoprotective effect of ischemic and anesthetic preconditioning before liver resection when using intermittent vascular inflow occlusion: a randomized clinical trial

BACKGROUND

Ischemic preconditioning (IPC) and anesthetic preconditioning (APC) have been reported to attenuate ischemia-reperfusion (IR) injury after liver resection under continuous inflow occlusion. This study evaluates whether these strategies enhance hepatic protection of remnant liver against IR after liver resection with intermittent clamping (INT).

METHODS

A total of 106 patients without underlying liver disease and submitted to liver resection using INT were randomized into 3 groups: IPC (10 minutes of inflow occlusion followed by 10 minutes of reperfusion before liver transection), APC (sevoflurane administration for 20 minutes before liver transection), and INT (no preconditioning). Patients were also stratified according to the extent of the hepatectomy. Cytoprotection was evaluated by comparing hepatocyte and endothelial dysfunction markers, apoptosis, histologic lesions, and postoperative outcome.

RESULTS

No differences were observed in preoperative chemotherapy and steatosis, total warm ischemia time, operative time, or blood loss. Kinetics of transaminases (aspartate aminotransferase, P = .137; alanine aminotransferase, P = .616), bilirubin (P = .980), and hyaluronic acid increase (P = .514) revealed no differences. Significant apoptosis was present in 40% of patients, mild-to-moderate leukocyte infiltration and steatosis in 45% and 55%, respectively, and mild sinusoidal congestion in 65%, with a similar distribution in the 3 groups. When patients were stratified by major versus minor resections, no differences were observed in any of the variables studied. Postoperative clinical outcomes were also similar.

CONCLUSION

These results suggest that these protocols of IPC and APC used in this study do not provide better cytoprotection from IR when INT is used.

Differential bradykinin B1 and B2 receptor regulation in cell death induced by hepatic ischaemia/reperfusion injury

In the present study, we have demonstrated that the kinin B1 receptor may participate in apoptotic cell death signalling, whereas the B2 receptor may be involved in necrotic cell death during IRI.

Hepatic ischemic preconditioning increases portal vein flow in experimental liver ischemia reperfusion injury

BACKGROUND

Ischemic preconditioning (IPC) has been shown to decrease liver injury and to increase hepatic microvascular perfusion after liver ischemia reperfusion. This study aimed to evaluate the effects of IPC on hemodynamics of the portal venous system.

METHODS

Thirty-two rats were randomized into two groups: IPC group and control group. The rats of the IPC group underwent IPC by 10 minutes of liver ischemia followed by 10 minutes of reperfusion before liver ischemia, and the rats of the control group were subjected to 60 minutes of partial liver ischemia. Non-ischemic lobes were resected immediately after reperfusion. The animals were studied at 4 hours and 12 hours after reperfusion. Mean arterial pressure, heart rate, portal vein flow and pressure were analyzed. Blood was collected for the determination of the levels of aspartate aminotransferase, alanine aminotransferase, calcium, lactate, pH, bicarbonate, and base excess.

RESULTS

IPC increased the mean portal vein flow at 4 hours and 12 hours after reperfusion. IPC recovered 78% of the mean portal vein flow at 12 hours after reperfusion. IPC decreased the levels of aspartate aminotransferase, alanine aminotransferase and lactate, and increased the levels of ionized calcium, bicarbonate and base excess at 12 hours after reperfusion.

CONCLUSIONS

This study demonstrated that IPC increases portal vein flow and enhances hepatoprotective effects in liver ischemia reperfusion. The better recovery of portal vein flow after IPC may be correlated with the lower levels of transaminases and with the better metabolic profile.

The effects of remote ischemic preconditioning and N-acetylcysteine with remote ischemic preconditioning in rat hepatic ischemia reperfusion injury model

Background. Remote ischemic preconditioning (RIP) and pharmacological preconditioning are the effective methods that can be used to prevent ischemia reperfusion (IR) injury. The aim of this study was to evaluate the effects of RIP and N-Acetylcysteine (NAC) with RIP in the rat hepatic IR injury model. Materials and Methods. 28 rats were divided into 4 groups. Group I (sham): only laparotomy was performed. Group II (IR): following 30 minutes of hepatic pedicle occlusion, 4 hours of reperfusion was performed. Group III (RIP + IR): following 3 cycles of RIP, hepatic IR was performed. Group IV (RIP + NAC + IR): following RIP and intraperitoneal administration of NAC (150 mg/kg), hepatic IR was performed. All the rats were sacrificed after blood samples were taken for the measurements of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver was processed for conventional histopathology. Results. The hepatic histopathological injury scores of RIP + IR and RIP + NAC + IR groups were significantly lower than IR group (P = 0.006, P = 0.003, resp.). There were no significant differences in AST and ALT values between the IR, RIP + IR, and RIP + NAC + IR groups. Conclusions. In the present study, it was demonstrated histopathologically that RIP and RIP + NAC decreased hepatic IR injury significantly.

Oxygen-sensitive mitochondrial accumulation of cystathionine β-synthase mediated by Lon protease

Oxygen-sensitive accumulation and degradation, two opposite but intrinsically linked events, of heme proteins in mitochondria affect mitochondrial functions, including bioenergetics and oxygen-sensing processes. Cystathionine β-synthase (CBS) contains a prosthetic heme group and catalyzes the production of hydrogen sulfide in mammalian cells. Here we show that CBS proteins were present in liver mitochondria at a low level under normoxia conditions. Ischemia/hypoxia increased the accumulation of CBS proteins in mitochondria. The normalization of oxygen partial pressure accelerated the degradation of CBS proteins. Lon protease, a major degradation enzyme in mitochondrial matrix, recognized and degraded mitochondrial CBS by specifically targeting at the oxygenated heme group of CBS proteins. The accumulation of CBS in mitochondria increased hydrogen sulfide production, which prevented Ca(2+)-mediated cytochrome c release from mitochondria and decreased reactive oxygen species generation. Mitochondrial accumulation of heme oxygenase-1, another heme protein, was also regulated by oxygen level and Lon protease in the same mechanism as for CBS. Our findings provide a fundamental and general mechanism for oxygen-sensitive regulation of mitochondrial functions by linking oxygenation level to the accumulation/degradation of mitochondrial heme proteins.

Identification of a Calcium Signalling Pathway of S-[6]-Gingerol in HuH-7 Cells

Calcium signals in hepatocytes control cell growth, proliferation, and death. Members of the transient receptor potential (TRP) cation channel superfamily are candidate calcium influx channels. NFκB activation strictly depends on calcium influx and often induces antiapoptotic genes favouring cell survival. Previously, we reported that S-[6]-gingerol is an efficacious agonist of the transient receptor potential cation channel subfamily V member 1 (TRPV1) in neurones. In this study, we tested the effect of S-[6]-gingerol on HuH-7 cells using the Fluo-4 calcium assay, RT-qPCR, transient cell transfection, and luciferase measurements. We found that S-[6]-gingerol induced a transient rise in [Ca²⁺]_i in HuH-7 cells. The increase in [Ca²⁺]_i induced by S-[6]-gingerol was abolished by preincubation with EGTA and was also inhibited by the TRPV1 channel antagonist capsazepine. Expression of TRPV1 in HuH-7 cells was confirmed by mRNA analysis as well as a test for increase of [Ca²⁺]_i by TRPV1 agonist capsaicin and its inhibition by capsazepine. We found that S-[6]-gingerol induced rapid NFκB activation through TRPV1 in HuH-7 cells. Furthermore, S-[6]-gingerol-induced NFκB activation was dependent on the calcium gradient and TRPV1. The rapid NFκB activation by S-[6]-gingerol was associated with an increase in mRNA levels of NFκB-target genes: cIAP-2, XIAP, and Bcl-2 that encode antiapoptotic proteins.

Allogeneic bone marrow-derived mesenchymal stem cells attenuate hepatic ischemia-reperfusion injury by suppressing oxidative stress and inhibiting apoptosis in rats

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been shown to attenuate ischemia reperfusion (IR) injury in the heart, brain and kidney. However, their exact roles in the liver remain to be defined. Our objective was to investigate the potential effects of BM-MSCs on a hepatic IR rat model during the first 24 h after reperfusion, a crucial period for hepatic IR damage formation. A rat model of normothermic partial hepatic ischemia was obtained by vascular clamping for 60 min. BM-MSCs were transplanted via portal vein injection. Injury severity, oxidative stress response and apoptosis of liver cells were assessed at 2, 6, 12 and 24 h after reperfusion and cell transplantation was evaluated. At 12 and 24 h after reperfusion, rats transplanted with BM-MSCs had significantly lower serum levels of alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST), fewer damaged liver tissues, higher superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and lower malondialdehyde (MDA) levels compared to rats in the sham transplantation group. At 24 h after reperfusion, IR rats transplanted with BM-MSCs had significantly fewer apoptotic hepatocytes, higher levels of B-cell lymphoma 2 (Bcl-2) protein, and lower levels of Bcl-2-associated X (Bax) and caspase-3 (Casp3) proteins compared to sham transplantation rats. In conclusion, BM-MSCs transplanted via the portal vein partially prevent hepatic IR injury by suppressing oxidative stress and inhibiting apoptosis during the first 24 h after reperfusion.

Recombinant human erythropoietin preconditioning attenuates liver ischemia reperfusion injury through the phosphatidylinositol-3 kinase/AKT/endothelial nitric oxide synthase pathway

BACKGROUND

The exact mechanism by which erythropoietin protects the liver from ischemia reperfusion (I/R) injury is not yet known. In the present study, we examined the role of protein kinase B (PKB/AKT) and endothelial nitric oxide synthase (eNOS) in the protective effect of recombinant human erythropoietin (rHuEPO) on I/R injury of the liver.

MATERIALS AND METHODS

We used a liver in situ I/R model. One hundred twenty adult male Sprague-Dawley rats were divided randomly into six groups. rHuEPO and (or) LY294002 were injected in the tail vein before the operation, and its effect was assessed by measuring the serum levels of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, nitric oxide (NO), and endothelin-1 (ET-1) and by histologic analysis. The expression of erythropoietin receptor (EPOR) and eNOS was measured by real-time polymerase chain reaction. Total AKT and eNOS and phosphorylated AKT and eNOS were examined by western blot.

RESULTS

rHuEPO dramatically attenuated the functional and morphologic injuries. The serum levels of alanine aminotransferase and lactate dehydrogenase were significantly decreased, but the amount of NO in the serum was increased in the I/R + rHuEPO group. Accordingly, rHuEPO administration significantly ameliorated the histologic damages at 6 h after reperfusion. rHuEPO significantly stimulated the phosphorylation of AKT and eNOS in the rats after liver I/R.

CONCLUSIONS

The protective effect of rHuEPO in I/R injury is mediated via the activation of the phosphatidylinositol-3 kinase/AKT/eNOS signaling pathway, at least in part, by increasing p-AKT and p-eNOS and leads to the maintenance of an elevated level of NO.

Toll-like receptor signaling in liver ischemia and reperfusion

Liver ischemia-reperfusion (I/R) injuries are significant clinical challenges implicated in various hepatic surgical procedures and transplantations. Associated with varying degrees of insult, the hallmark of I/R is the excessive inflammatory response potentiated by the host immune system. Toll-like receptors (TLRs), known to play an important role in pathogen-derived inflammation, are now thought to participate in I/R injury-derived inflammation signaling pathways. Endogenous particles (proteins, cytokines, nucleic acids) that are released from damaged host cells bind to TLR2, TLR4, and TLR9, resulting in even further injury by subsequent inflammatory reactions and activation of the innate immune system. This review aims to systematically examine the current literature about TLR signaling mechanisms, allowing for a greater understanding of the precise role of TLRs in hepatic I/R injuries.

Effect of taurine on IRAK4 and NF-kappa B in Kupffer cells from rat liver grafts after ischemia-reperfusion injury

BACKGROUND

The aim of this study was to explore the protective mechanisms of taurine pretreatment against hepatic ischemia/reperfusion injury after liver transplantation.

METHODS

A Sprague-Dawley-to-Sprague-Dawley rat liver transplantation model was used in this study. At 0, 60, and 180 minutes after reperfusion, expression of interleukin-1 receptor-associated kinase-4 (IRAK-4) messenger ribonucleic acid and protein in Kupffer cells was determined by real-time polymerase chain reaction and Western blotting. The activity of nuclear factor κB in Kupffer cells was determined by electrophoretic mobility shift assay. The serum tumor necrosis factor-α level was detected by enzyme-linked immunosorbent assay. Serum transaminases, liver histology, and animal survival were also investigated.

RESULTS

At 60 and 180 minutes after reperfusion, levels of IRAK-4 messenger ribonucleic acid and protein, activities of nuclear factor κB, and levels of serum transaminases and tumor necrosis factor-α were all obviously elevated. However, changes in these parameters in rats treated with taurine were remarkably attenuated at the indicated time points.

CONCLUSIONS

These data suggest that taurine could protect against hepatic ischemia/reperfusion injury after liver transplantation, and the protective effects may be through downregulation of IRAK-4 and downstream nuclear factor κB and tumor necrosis factor-α expression in Kupffer cells.

Mangafodipir protects against hepatic ischemia-reperfusion injury in mice

Introduction and Aim

Mangafodipir is a contrast agent used in magnetic resonance imaging that concentrates in the liver and displays pleiotropic antioxidant properties. Since reactive oxygen species are involved in ischemia-reperfusion damages, we hypothesized that the use of mangafodipir could prevent liver lesions in a mouse model of hepatic ischemia reperfusion injury. Mangafodipir (MnDPDP) was compared to ischemic preconditioning and intermittent inflow occlusion for the prevention of hepatic ischemia-reperfusion injury in the mouse.

Methods

Mice were subjected to 70% hepatic ischemia (continuous ischemia) for 90 min. Thirty minutes before the ischemic period, either mangafodipir (10 mg/kg) or saline was injected intraperitoneally. Those experimental groups were compared with one group of mice preconditioned by 10 minutes' ischemia followed by 15 minutes' reperfusion, and one group with intermittent inflow occlusion. Hepatic ischemia-reperfusion injury was evaluated by measurement of serum levels of aspartate aminotransferase (ASAT) activity, histologic analysis of the livers, and determination of hepatocyte apoptosis (cytochrome c release, caspase 3 activity). The effect of mangafodipir on the survival rate of mice was studied in a model of total hepatic ischemia.

Results

Mangafodipir prevented experimental hepatic ischemia-reperfusion injuries in the mouse as indicated by a reduction in serum ASAT activity (P<0.01), in liver tissue damages, in markers of apoptosis (P<0.01), and by higher rates of survival in treated than in untreated animals (P<0.001). The level of protection by mangafodipir was similar to that observed following intermittent inflow occlusion and higher than after ischemic preconditioning.

Conclusions

Mangafodipir is a potential new preventive treatment for hepatic ischemia-reperfusion injury.

Hepatic steatosis prevents heme oxygenase-1 induction by isoflurane in the rat liver

AIM: To characterize the inductive effects of isoflurane (ISO) on hepatic heme oxygenase-1 (HO-1) in an animal model of hepatic steatosis.

METHODS: Lean (LEAN) and obese (FAT) Zucker rats were randomized into 4 groups: 1: LEAN + pentobarbital sodium (PEN); 2: LEAN + ISO; 3: FAT + PEN; 4: FAT + ISO. The animals were mechanically ventilated for 6 h. In vitro analyses of liver tissue included determination of HO-1 mRNA and protein expression as well as measurement of HO enzyme activity and immunohistochemical analyses.

RESULTS: Compared to PEN treatment, ISO administration profoundly induced hepatic HO-1 mRNA and protein expression and significantly increased HO enzyme activity in lean Zucker rats. In contrast, no difference in HO-1 gene expression was observed after ISO or PEN anesthesia in obese Zucker rats.

CONCLUSION: The present study demonstrates that ISO is an inducer of hepatic HO-1 gene expression in non-steatotic organs but failed to upregulate HO-1 in steatotic livers.

Expression and function of TRP channels in liver cells

The liver plays a central role in whole body homeostasis by mediating the metabolism of carbohydrates, fats, proteins, drugs and xenobiotic compounds, and bile acid and protein secretion. Hepatocytes together with endothelial cells, Kupffer cells, smooth muscle cells, stellate and oval cells comprise the functioning liver. Many members of the TRP family of proteins are expressed in hepatocytes. However, knowledge of their cellular functions is limited. There is some evidence which suggests the involvement of TRPC1 in volume control, TRPV1 and V4 in cell migration, TRPC6 and TRPM7 in cell proliferation, and TRPPM in lysosomal Ca(2+) release. Altered expression of some TRP proteins, including TRPC6, TRPM2 and TRPV1, in tumorigenic cell lines may play roles in the development and progression of hepatocellular carcinoma and metastatic liver cancers. It is likely that future experiments will define important roles for other TRP proteins in the cellular functions of hepatocytes and other cell types of which the liver is composed.

Intracellular calcium signaling pathways during liver ischemia and reperfusion

Calcium plays a major role in intracellular signaling mechanisms during ischemia reperfusion (I/R) injury of a liver cell. Under ischemic conditions, the absence of oxygen arrests oxidative phosphorylation, thereby eliminating the energy source by which hepatocellular mechanisms maintain homeostasis of calcium. This, in turn, leaves nonselective plasma membrane influx pores unopposed and results in a net increase in intracellular calcium concentrations. Subsequent reperfusion marks the onset and progression of apoptosis and necrosis, as it involves inflammatory responses as well as free-radical formation due to re-oxygenation of cells. These processes destroy the structural integrity of organelles, leading to disruptive redistribution of calcium between cellular and subcellular compartments. This initial elevation and later imbalance of intracellular calcium concentrations associated with I/R induce various molecular responses within each organelle. In the cytoplasm, a series of pro-apoptotic pathways involving various calcium sensitive enzymes are activated. The injury is further exacerbated in the endoplasmic reticulum (ER) due to the malfunction of mechanisms responsible for intracellular calcium sequestration. Both the mitochondria and the nucleus are also adversely affected, as their structural integrity and physiologic functions are disrupted. To date, however, the precise pathophysiology of these calcium-mediated signaling pathways is not fully understood due to its complex nature. This review aims to systematically examine the current literature about individual molecular signaling pathways in the cytoplasm, ER, mitochondria, and the nucleus prior to causing time-sensitive progression of permanent tissue injury.

Liver ischemia/reperfusion injury: processes in inflammatory networks--a review

Liver ischemia/reperfusion (IR) injury is typified by an inflammatory response. Understanding the cellular and molecular events underpinning this inflammation is fundamental to developing therapeutic strategies. Great strides have been made in this respect recently. Liver IR involves a complex web of interactions between the various cellular and humoral contributors to the inflammatory response. Kupffer cells, CD4+ lymphocytes, neutrophils, and hepatocytes are central cellular players. Various cytokines, chemokines, and complement proteins form the communication system between the cellular components. The contribution of the danger-associated molecular patterns and pattern recognition receptors to the pathophysiology of liver IR injury are slowly being elucidated. Our knowledge on the role of mitochondria in generating reactive oxygen and nitrogen species, in contributing to ionic disturbances, and in initiating the mitochondrial permeability transition with subsequent cellular death in liver IR injury is continuously being expanded. Here, we discuss recent findings pertaining to the aforementioned factors of liver IR, and we highlight areas with gaps in our knowledge, necessitating further research.

Functional interactions among STIM1, Orai1 and TRPC1 on the activation of SOCs in HL-7702 cells

STIM1, Orai1 and TRPC1 are all reported to be important for store-operated Ca(2+) entry (SOCE) in diverse cells. However, there is no evidence for the functional interaction of the three proteins in SOCE in human liver cells. The objective of this study is to determine whether they are involved in SOCE in normal human liver cells. Liposomal transfection method was used to increase expression levels of the three proteins in HL-7702 cells, a normal human liver cell line. Western blot and single cell RT-PCR were applied to evaluate transfection effectiveness. Changes in store-operated current (I(SOC)) and SOCE were investigated using whole-cell patch-clamp recording and calcium imaging. I(SOC) is detected in HL-7702 cells and it is inhibited either by 2-Aminoethoxydiphenyl borate (2-APB) or La(3+). Overexpression of STIM1 or Orai1 alone did not induce any change in I(SOC). TRPC1-transfection, however, caused approximate 2.5-fold increase in I(SOC). A large increase (>10-fold) in I(SOC) emerged when both STIM1 and Orai1 were co-transfected into HL-7702 cells. Co-overexpression of STIM1 + TRPC1 also caused >10-fold increase in I(SOC), and addition of Orai1 did not cause any further increase. In HL-7702 cells, TRPC1 and Orai1 take part in SOCE independently of each other. Functional interactions of STIM1 and Orai1 or TRPC1 contribute to I(SOC) activation.

Intermittent ischaemia maintains function after ischaemia reperfusion in steatotic livers

BACKGROUND

Ischaemic preconditioning (IPC) and intermittent ischaemia (INT) reduce liver injury after ischaemia reperfusion (IR). Steatotic livers are at a higher risk of IR injury, but the protection offered by IPC and INT is not well understood. The aim of the present study was to determine the effectiveness of IPC and INT in maintaining liver function in steatotic livers.

MATERIAL AND METHODS

A model of segmental hepatic ischaemia (45 min) and reperfusion (60 min) was employed using lean and obese Zucker rats. Bile flow recovery was measured to assess dynamic liver function, hepatocyte fat content quantified and blood electrolytes, metabolites and bile calcium measured to assess liver and whole body physiology. Liver marker enzymes and light and electron microscopy were employed to assess hepatocyte injury.

RESULTS

IPC was not effective in promoting bile flow recovery after IR in either lean or steatotic livers, whereas INT promoted good bile flow recovery in steatotic as well as lean livers. However, the bile flow recovery in steatotic livers was less than that in lean livers. In steatotic livers, ischaemia led to a rapid and substantial decrease in fat content. Steatotic livers were more susceptible to IR injury than lean livers, as indicated by increased blood ALT concentrations and major histological injury.

CONCLUSION

INT is more effective than IPC in restoring liver function in the acute phase of IR in steatotic livers. In obese patients, INT may be useful in promoting better liver function after IR after liver resection.

Reversible mitochondrial uncoupling in the cold phase during liver preservation/reperfusion reduces oxidative injury in the rat model

Reversible uncoupling of the mitochondrial electron-transport chain may be one strategy to prevent intracellular oxidative stress during liver cold preservation/warm reperfusion (CP/WR) injury. 2,4-Dinitrophenol (DNP) is a potent water-soluble uncoupling agent for supplementation of the hepatic CP solution. The aim of this work was to investigate the possible influence of DNP in the CP solution on the isolated rat liver state during CP/WR. Livers were subjected to CP at 4 degrees C in sucrose-phosphate based solution (SPS) for 18 h, followed by WR for 60 min in vitro. The final concentration of DNP was 100 microM. DNP presence during the CP stage led to partial ATP level decrease accompanied by a significant diminution in liver TBARS and a prevention of antioxidant enzyme activity decrease (catalase, GSH-PO, GSH-Red) when compared with livers stored without DNP. After DNP wash-out during WR, an improvement in the mitochondrial functional state (higher respiratory control indices and ATP levels, and a decrease in V(4) respiration rates) were observed. This was concurrent with lower TBARS levels, higher antioxidant enzyme activities and significant increase of bile production. The results suggest that reversible uncoupling may be one way to influence oxidative stress associated with hepatic cold preservation.

Measuring Ca2+ influxes of TRPC1-dependent Ca2+ channels in HL-7702 cells with non-invasive micro-test technique

AIM

To explore the possibility of using the Non-invasive Micro-test Technique (NMT) to investigate the role of Transient Receptor Potential Canonical 1 (TRPC1) in regulating Ca(2+) influxes in HL-7702 cells, a normal human liver cell line.

METHODS

Net Ca(2+) fluxes were measured with NMT, a technology that can obtain dynamic information of specific/selective ionic/molecular activities on material surfaces, non-invasively. The expression levels of TRPC1 were increased by liposomal transfection, whose effectiveness was evaluated by Western-blotting and single cell reverse transcription-polymerase chain reaction.

RESULTS

Ca(2+) influxes could be elicited by adding 1 mmol/L CaCl(2) to the test solution of HL-7702 cells. They were enhanced by addition of 20 micromol/L noradrenaline and inhibited by 100 micromol/L LaCl(3) (a non-selective Ca(2+) channel blocker); 5 micromol/L nifedipine did not induce any change. Overexpression of TRPC1 caused increased Ca(2+) influx. Five micromoles per liter nifedipine did not inhibit this elevation, whereas 100 micromol/L LaCl(3) did.

CONCLUSION

In HL-7702 cells, there is a type of TRPC1-dependent Ca(2+) channel, which could be detected via NMT and inhibited by La(3+).

Ischemic preconditioning protects the pig liver by preserving the mitochondrial structure and downregulating caspase-3 activity

BACKGROUND DATA

The beneficial effects of ischemic preconditioning (IPC) on hepatic ischemia-reperfusion injury (I/RI) have been described. However, the way in which IPC causes the changes in mitochondrial ultrastructure seen in hepatic I/RI is not well understood.

OBJECTIVE

The objective of the present study was to determine whether IPC protects the liver from changes in mitochondrial structure and caspase 3 activity in the early phase of post-ischemic injury.

METHODS

A pig model consisting of 90 min of hepatic ischemia and 180 min of reperfusion was employed. Eighteen female pigs were randomly divided into three groups: sham-operated, non-preconditioned, and ischemic preconditioned (10 min ischemia followed by 10 min reperfusion). Serum concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and thiobarbituric acid reactive substances (TBARS), as well as bile flow, were measured. Liver biopsies were taken after reperfusion for histological, immunohistochemical (anti-caspase 3), and ultrastructural examinations.

RESULTS

The IPC procedure increased bile flow (p < 0.01), reduced serum AST level (p < 0.01), and reduced serum concentration of TBARS at 180 min of reperfusion (p = 0.05). Ischemic-preconditioned liver cells had less caspase 3 activity than the non-preconditioning group (p < 0.01), and changes in mitochondrial ultrastructure were reduced (p < 0.01).

CONCLUSION

IPC exerts a powerful protective effect against hepatic I/RI in the early phase of reperfusion, which may be mediated by preservation of mitochondrial structure and inhibition of caspase-3 activity.

Plasma bilirubin correlations in non-obstructive cholestasis after partial hepatectomy

BACKGROUND

The aim of this study was to provide an improved outline of the patterns and correlates of changes in plasma bilirubin after partial hepatectomy.

METHODS

A large series of blood measurements and complementary variables were prospectively collected from 85 patients undergoing liver resection, and bilirubin correlations were assessed by regression analysis.

RESULTS

Early postoperatively, the best simultaneous correlates of increasing bilirubin were the preoperative value, the duration of surgery, and the number of blood transfusions (r2 = 0.74, p < 0.001). Subsequently, increasing bilirubin became related to the number of resected liver segments, the duration of intraoperative liver ischemia, the use of continuous vs. intermittent ischemia, and the presence of sepsis (r2 = 0.82, p < 0.001); these were also the best simultaneous correlates of peak bilirubin. This pattern was characterized by prominently conjugated hyperbilirubinemia, hypocholesterolemia, and moderately increased alkaline phosphatase, and occurred in the absence of obstructive cholestasis.

CONCLUSIONS

Major hepatectomy, parenchymal ischemia, and sepsis have similar and synergistic impacts as determinants of prominently conjugated hyperbilirubinemia after liver resection. This is likely related to impaired hepatocellular bilirubin transport and occurs in the absence of obstructive components.

Use of dissecting sealer may affect the early outcome in patients submitted to hepatic resection

BACKGROUND

Many technological devices have been used to avoid intraoperative bleeding during hepatic parenchymal transection and to avoid morbidity and mortality, but until now none is complete. The aim of this work is to prospectively analyze hepatic resection patients treated with a water-cooled high frequency monopolar device in order to evaluate its effectiveness.

PATIENTS AND METHODS

All consecutive patients who underwent liver resection by use of this device, between January 2003 until December 2007, were analyzed prospectively. The following variables were considered: age, sex, kind of disease, kind of liver resection, number of major/minor resections, total operative time and transection time, number and time of clamping, blood loss, time of hospitalization, morbidity, and mortality.

RESULTS

Between January 2003 and December 2007, 26 patients were analyzed prospectively (69% women, 31% men). Ages ranged from 18 to 84 years. Sixty-five percent of patients had a malignant disease; 35%, a benign disease. The procedures performed were two major hepatectomies (7.6%) and 24 minor hepatectomies (92.4%). Hepatic transection was performed in 35 to 150 min. Total operative time range was 120-480 min. The average blood loss was 325 ml (range 50-600 ml). The mean postoperative stays were nine days for all the patient and six days for non-cirrhotic patients.

CONCLUSION

The water-cooled high frequency monopolar device is useful for reducing ischemia-reperfusion damage due to the Pringle maneuver and for reducing the risk of morbidity. However, the Kelly forceps remains the only inexpensive instrument really essential for liver surgery.

Ca(2+) -permeable channels in the hepatocyte plasma membrane and their roles in hepatocyte physiology

Hepatocytes are highly differentiated and spatially polarised cells which conduct a wide range of functions, including intermediary metabolism, protein synthesis and secretion, and the synthesis, transport and secretion of bile acids. Changes in the concentrations of Ca(2+) in the cytoplasmic space, endoplasmic reticulum (ER), mitochondria, and other intracellular organelles make an essential contribution to the regulation of these hepatocyte functions. While not yet fully understood, the spatial and temporal parameters of the cytoplasmic Ca(2+) signals and the entry of Ca(2+) through Ca(2+)-permeable channels in the plasma membrane are critical to the regulation by Ca(2+) of hepatocyte function. Ca(2+) entry across the hepatocyte plasma membrane has been studied in hepatocytes in situ, in isolated hepatocytes and in liver cell lines. The types of Ca(2+)-permeable channels identified are store-operated, ligand-gated, receptor-activated and stretch-activated channels, and these may vary depending on the animal species studied. Rat liver cell store-operated Ca(2+) channels (SOCs) have a high selectivity for Ca(2+) and characteristics similar to those of the Ca(2+) release activated Ca(2+) channels in lymphocytes and mast cells. Liver cell SOCs are activated by a decrease in Ca(2+) in a sub-region of the ER enriched in type1 IP(3) receptors. Activation requires stromal interaction molecule type 1 (STIM1), and G(i2alpha,) F-actin and PLCgamma1 as facilitatory proteins. P(2x) purinergic channels are the only ligand-gated Ca(2+)-permeable channels in the liver cell membrane identified so far. Several types of receptor-activated Ca(2+) channels have been identified, and some partially characterised. It is likely that TRP (transient receptor potential) polypeptides, which can form Ca(2+)- and Na(+)-permeable channels, comprise many hepatocyte receptor-activated Ca(2+)-permeable channels. A number of TRP proteins have been detected in hepatocytes and in liver cell lines. Further experiments are required to characterise the receptor-activated Ca(2+) permeable channels more fully, and to determine the molecular nature, mechanisms of activation, and precise physiological functions of each of the different hepatocyte plasma membrane Ca(2+) permeable channels.

Intermittent ischemia but not ischemic preconditioning is effective in restoring bile flow after ischemia reperfusion injury in the livers of aged rats

BACKGROUND/AIMS

Ischemic preconditioning (IPC) and intermittent ischemia (INT) reduce liver injury following ischemia reperfusion in liver resections. Aged livers are at higher risk for ischemia reperfusion injury, but little is known of the effectiveness of IPC and INT in aged livers. The aim of this study was to investigate the effects of IPC and INT on ischemia reperfusion injury in aged livers.

METHODS

A rat model of segmental hepatic ischemia (45 min) and reperfusion (60 min) was used. Bile flow, as an indicator of early hepatocyte damage and dynamic liver function, plasma concentrations of bilirubin, liver marker enzymes, and liver histology were assessed.

RESULTS

In young rats (8-13 weeks), IPC regimes of 10 min clamping and 10 min reperfusion, and 5 min clamping and 30 min reperfusion, restored bile flow to 23 and 42%, respectively, of the initial value, compared to 14 and 88% for continuous clamping and controls, respectively. An INT regime of three cycles of alternating 15 min perfusion and 15 min clamping gave a substantially greater (70%) restoration of bile flow. In aged rats (20-24 months), the IPC regimes did not give any restoration of bile flow. By contrast, the INT regime restored bile flow to 68%. Plasma bilirubin concentrations were lowest in the INT groups, whereas alanine transaminase concentrations for the IPC and INT groups compared with the continuous clamping groups showed no significant differences.

CONCLUSIONS

In young rats, INT is more effective than IPC in restoring the immediate consequences of IP-induced damage to hepatocytes and liver function after ischemia-reperfusion. In aged rats INT, but not IPC, reverses hepatocyte damage and restores liver function. INT may promote better hepatocyte and liver function than IPC following the surgical resection of aged livers.

The protective effects of intravenous anesthetics and verapamil in gut ischemia/reperfusion-induced liver injury

BACKGROUND

We investigated the protective effects of IV anesthetics and verapamil in gut ischemia/reperfusion-induced liver injury.

METHODS

Forty male Wistar Albino rats were randomly assigned to four groups of 10 rats each. Anesthesia was induced and maintained with propofol in Groups 1 and 3 and with thiopental in Groups 2 and 4 during the experiment. All animals developed intestinal ischemia after occlusion of the superior mesenteric artery for 30 min. Reperfusion was induced by removal of the microvascular clamp and was allowed to continue for 120 min. The animals in Groups 3 and 4 were given verapamil 10 min before reperfusion. Liver and ileum samples were taken for measurement of malondialdehyde (MDA) and histopathologic examination before ischemia and 30 and 120 min after reperfusion. Blood samples were also obtained for measurement of plasma tumor necrosis factor-alpha and interleukin-6 levels.

RESULTS

Gut ischemia/reperfusion-induced significant increases in MDA contents of liver and gut and serum cytokines, consistent with histopathologic injury scores. Propofol effectively stabilized the MDA levels and decreased the tissue injury scores of the liver and gut. Tumor necrosis factor-alpha and interleukin-6 levels increased less in the propofol groups than in the thiopental groups. There was no additive preventive effect of verapamil on propofol. The addition of verapamil to thiopental was effective in decreasing the serum cytokines and liver MDA content.

CONCLUSION

Propofol may offer advantages by inhibiting lipid peroxidation and inflammatory cytokine production in an animal model of gut ischemia/reperfusion-induced liver injury.

Ischemic preconditioning and intermittent ischemia preserve bile flow in a rat model of ischemia/reperfusion injury

Ischemia and reperfusion (IR) injury of the liver is associated with impaired bile secretion, but the effects of ischemic preconditioning (IPC) and intermittent ischemia (INT) on bile flow are unknown. A rat model of segmental (60%-70%) hepatic ischemia and reperfusion was employed to test the effects of IPC and INT on bile flow. Continuous clamping for 45 min (CC) substantially reduced bile flow, and this did not recover after 60 min of reperfusion. IPC and INT caused a significant recovery of bile flow. The elevation in plasma liver marker enzymes induced by CC was not reduced by IPC and INT. Light microscopy showed mild hepatocyte damage in all groups. In the CC group, the amount of F-actin localized around the bile canaliculi in the ischemic lobes was less than that in the nonischemic lobes, but this difference was not observed in the IPC and INT groups. It is concluded that IPC and INT substantially alleviate the decrease in bile flow induced by ischemia. Bile flow may be useful in the assessment of IR injury.

Ischemic preconditioning and intermittent ischemia preserve bile flow in a rat model of ischemia reperfusion injury

Ischemia and reperfusion (IR) injury of the liver is associated with impaired bile secretion, but the effects of ischemic preconditioning (IPC) and intermittent ischemia (INT) on bile flow are unknown. A rat model of segmental (60%-70%) hepatic ischemia and reperfusion was employed to test the effects of IPC and INT on bile flow. Continuous clamping for 45 min (CC) substantially reduced bile flow, and this did not recover after 60 min of reperfusion. IPC and INT caused a significant recovery of bile flow. The elevation in plasma liver marker enzymes induced by CC was not reduced by IPC and INT. Light microscopy showed mild hepatocyte damage in all groups. In the CC group, the amount of F-actin localized around the bile canaliculi in the ischemic lobes was less than that in the nonischemic lobes, but this difference was not observed in the IPC and INT groups. It is concluded that IPC and INT substantially alleviate the decrease in bile flow induced by ischemia. Bile flow may be useful in the assessment of IR injury.