Investigation of the renal injury caused by liver ischemia-reperfusion in rats

Renoprotective effect of vildagliptin following hepatic ischemia/reperfusion injury

Remote renal injury is a drastic consequence of hepatic ischemia/reperfusion (IR) injury. Vildagliptin (V) is a dipeptidyl peptidase-4 inhibitor that has a hepatorenal protective effect against models of liver and renal IR. This research was done to explore the protective role of vildagliptin against renal injury following hepatic IR injury as well as the possible involvement of transforming growth factor-beta (TGF-β)/Smad/alpha-smooth muscle actin (α-SMA) expressions in the pathophysiological mechanism of the remote renal injury. Three groups of male Wistar rats were organized into: sham group, IR group, and V + IR group in which 10 mg/kg/day of vildagliptin was pretreated for 10 days intraperitoneally. Blood in addition to renal and hepatic tissue samples was used for biochemical and histopathological studies. Hepatic IR induced a marked increase in serum creatinine, blood urea nitrogen, liver enzymes, renal nitric oxide, malondialdehyde, tumor necrosis factor-alpha levels with a marked upregulation of renal mRNA expressions of TGF-β, Smad2, Smad3, and α-SMA in addition to a marked decline in renal catalase content comparing to the sham group. Abnormal histopathological findings of hepatic and renal injury were detected in the IR group. Vildagliptin significantly improved these biochemical markers as well as the histopathological changes. The upregulation of renal TGF-β/Smad/α-SMA mRNA expressions was involved for the first time in the pathogenesis of the renal injury following hepatic IR and vildagliptin ameliorated this renal injury through blocking these expressions.

Acute kidney injury after hepatic ischemia and reperfusion injury in mice

Hepatic ischemia reperfusion (IR) is the leading cause of acute liver failure (ALF) during the perioperative period and patients with ALF frequently develop acute kidney injury (AKI). There is no effective therapy for AKI associated with ALF because pathomechanisms are incompletely characterized, in part due to the lack of an animal model. In this study, we characterize a novel murine model of AKI following hepatic IR. Mice subjected to approximately 70% liver IR not only developed acute liver dysfunction, but also developed severe AKI 24 h after liver injury. Mice subjected to liver IR developed histological changes of acute tubular injury including focal proximal tubular cell necrosis involving the S3 segment, cortical tubular ectasia, focal tubular simplification and granular bile/heme cast formation. In addition, there was focal interstitial edema and hyperplasia of the juxtaglomerular apparatus. Inflammatory changes in the kidney after hepatic IR included neutrophil infiltration of the interstitium and upregulation of several proinflammatory mRNAs (tumor necrosis factor-alpha, keratinocyte-derived cytokine, monocyte chemotactic protein-1, macrophage inflammatory protein-2, intercellular adhesion molecule-1). In addition, marked renal endothelial cell apoptosis was detected involving peritubular interstitial capillaries, accompanied by increased renal vascular permeability. Finally, there was severe disruption of renal proximal tubule epithelial filamentous-actin. Our results show that AKI rapidly and reproducibly develops in mice after hepatic IR and is characterized by renal tubular necrosis, inflammatory changes and interstitial capillary endothelial apoptosis. Our murine model of AKI after liver injury closely mimics human AKI associated with ALF and may be useful in delineating the mechanisms and potential therapies for this common clinical condition.

The effects of desferrioxamine and quercetin on hepatic ischemia-reperfusion induced renal disturbance

BACKGROUND

The aim of this study was to analyze the effects of 45min of hepatic ischemia and 1h of reperfusion on renal oxidative stress parameters, on renal tissue damage, and the role of Desferrioxamin (Dfx) and Q on these parameters.

METHODS

Thirty Wistar albino rats were randomized to five groups. Group I was the control group. Group II received no treatment. Groups III and IV received intramuscular injections of desferrioxamine (100mg/kg) and quercetin (50mg/kg), respectively. Group V was administered Dfx and quercetin in combination. After treatment for 3 days, groups II, III, IV, and V were exposed to total hepatic ischemia for 45min. Plasma alanine aminotransferase levels, renal malondialdehyde and reduced glutathione (GSH) activities were measured after reperfusion for 1h. Histopathological and ultrastructural analysis of renal tissues was carried out.

RESULTS

Plasma creatinine and BUN levels were markedly increased in the IR group and pretreated groups. Kidney MDA increased in the IR group, Q and Dfx+Q significantly decreased kidney MDA Kidney GSH levels markedly decreased in the IR group, Dfx significantly increased kidney GSH. No evidence of overt injury was observed in any renal tissue under light and electron microscopy.

CONCLUSIONS

Our data demonstrated that 45min of hepatic ischemia and 1h of reperfusion may alter renal functions and may cause oxidative stress on renal tissue. Q and Dfx seem to have a beneficial effect via the GSH system and modulation of MDA levels.

High density lipoprotein (HDL) reduces renal ischemia/reperfusion injury

High-density lipoproteins (HDL) have been shown to reduce organ injury and mortality in animal models of shock via modulation of the expression of adhesion molecules and pro-inflammatory enzymes. As renal inflammation plays an important role in the development of ischemia/reperfusion (I/R) injury of the kidney, the aim of this study was to investigate the ability of HDL to alleviate renal dysfunction and injury in a rat model of renal I/R. HDL (80 mg/kg, intravenous) was administered to male Wistar rats 30 min before bilateral renal ischemia for 45 min followed by reperfusion for up to 48 h. After 6-h reperfusion, HDL significantly reduced (1) renal and tubular dysfunction, (2) tubular and reperfusion-injury, and (3) histologic evidence of renal injury. HDL also improved renal function (after 24-h and 48-h reperfusion) and reduced histologic signs of renal injury (after 48-h reperfusion). Administration of HDL significantly reduced the numbers of polymorphonuclear leukocytes (PMN) infiltrating into renal tissues during reperfusion, which was reflected by an attenuation of the increase in renal myeloperoxidase activity caused by I/R. Furthermore, HDL markedly reduced expression of the adhesion molecules, intercellular adhesion molecule-1 (ICAM-1), and P-selectin during reperfusion. The increase in renal malondialdehyde levels caused by renal I/R was also significantly reduced by HDL, suggesting attenuation of lipid peroxidation subsequent to oxidative stress. These results demonstrate that HDL significantly reduces renal I/R injury and severity of ischemic acute renal failure. It is proposed that the mechanism of protection involves reduction of the expression of adhesion molecules, resulting in reduction of PMN infiltration and oxidative stress.

Change in free radical-related substances in plasma following ischemia-reperfusion in rat liver

In order to clarify the relationship between free radicals and liver injury due to ischemia-reperfusion, we investigated the dynamics of radical-related substances in the blood of rats after liver ischemia-reperfusion. Subsequent to 60 min of liver ischemia, the generation of reactive oxygen species (ROS) from polymorphonuclear leukocytes (PMNs) initiated by phorbol myristate acetate (PMA) and lipid peroxidation significantly increased 2 h after reperfusion and showed peak values at 8-10 h. These values returned to the control level 32 h after reperfusion. The levels of nitric oxide metabolites (NO(x), NO(2)(-)+NO(3)(-)) increased biphasically at 10 and 32 h during the period of reperfusion, but did not return to control levels. Cu,Zn-superoxide dismutase (SOD) levels increased immediately after 5 min of reperfusion and showed a peak value after 20 min. This increase diminished gradually and returned to the control level 10 h after reperfusion. Mn-SOD increased 2 h after reperfusion, and this level was maintained for 48 h. The levels did not show increases at the end of ischemia and were nearly identical to the pre-ischemia levels. These finding obtained from the dynamics of radical-related substances are considered very meaningful for investigating mechanisms in the pathogenesis of liver injury by ischemia-reperfusion, and are clinically important in liver transplantation.

Protective effect of low dose of ascorbic acid on hepatobiliary function in hepatic ischemia/reperfusion in rats

BACKGROUND/AIMS

The aim of this study was to investigate the effect of ascorbic acid (AA) an alterations in hepatic secretory and microsomal functions during hepatic ischemia and reperfusion.

METHODS

Rats were subjected to 60 min of hepatic ischemia, and 1 and 5 h of reperfusion. Five minutes prior to ischemia, the animals were administered either vehicle or ascorbic acid (AA) (30, 100, 300, and 1000 mg/kg) intravenously.

RESULTS

The serum aminotransferase level and lipid peroxidation were markedly higher as a result of ischemia/reperfusion. These increases were significantly attenuated by AA doses of 30 and 100 mg/kg but were augmented by dose of 1000 mg/kg. Bile flow and cholate output were markedly decreased by ischemia/reperfusion. AA doses of 30 and 100 mg/kg restored but dose of 1000 mg/kg inhibited their secretion. Both the cytochrome P(450) content and aminopyrine N-demethylase activity were decreased by ischemia/reperfusion, which were prevented by AA doses of 30 and 100 mg/kg but were aggravated by dose of 1000 mg/kg. Aniline p-hydroxylase activity was elevated by ischemia/reperfusion, and this was prevented by AA doses of 100, 300 and 1000 mg/kg.

CONCLUSIONS

Ischemia/reperfusion diminishes the hepatic secretory and microsomal functions. AA has both antioxidant and pro-oxidant effects, depending upon the dose.

The roles of platelet-activating factor and endothelin-1 in renal damage after total hepatic ischemia and reperfusion

BACKGROUND

This study was designed to verify the involvement of platelet-activating factor (PAF) in renal damage associated with hepatic ischemia and reperfusion (HIR) injury through the release of endothelin (ET)-1 and to determine the modulating effect of a specific PAF receptor antagonist on these insults in rats.

METHODS

Male rats pretreated with either normal saline as a vehicle (NS group) or intravenous TCV-309, a PAF receptor antagonist (TCV group), were subjected to 120 min of total hepatic ischemia under an extracorporeal portosystemic shunt. Plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight were determined under nonischemic conditions and at 1, 3, and 6 hr of reperfusion after hepatic ischemia. Changes in mean arterial blood pressure and renal tissue blood flow measurements in the kidney were determined throughout the experiment.

RESULTS

Increased plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight after HIR in the NS group were significantly suppressed by TCV-309 pretreatment. Mean arterial blood pressure and renal tissue blood flow after HIR in the TCV group were significantly improved when compared with those in the NS group. These effects resulted in attenuation of structural hepatic and renal damage with the improvement of 7-day survival (62%).

CONCLUSIONS

The present study demonstrates that renal damage as well as critical liver injury is produced after reperfusion following 120 min of total hepatic ischemia. A PAF receptor antagonist may be therapeutically useful to protect against these types of damage via indirect modulation of plasma ET-1 levels.

Intermittent hepatic pedicle clamping reduces liver and lung injury

BACKGROUND

Temporary occlusion of the hepatic hilum is used to control hemorrhage during liver resection, but can result in widespread organ dysfunction.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to either continuous (Group C) or intermittent (Group R) hepatic ischemia. The total ischemia time (60 min) was divided into four 15-min periods in Group R. Blood and lung tissue specimens were collected 2 h after the induction of ischemia (early phase), and 24 h after the termination of ischemia (late phase). Plasma lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) concentrations were measured. Histologic sections were studied using hematoxylin and eosin, as well as naphthol AS-D chloroacetate esterase techniques.

RESULTS

In the early phase, LDH, ALT, TNF-alpha, and IL-6 concentrations were significantly higher in Group C than in Group R. Pulmonary septal thickening and polymorphonuclear leukocyte infiltration were less severe in Group R than in Group C. These differences were significant in the late phase.

CONCLUSIONS

Intermittent hepatic pedicle clamping reduces the ischemia-reperfusion injury not only to the liver but also to the lungs. This technique may improve the outcome in patients undergoing liver resection.