Hepatosplanchnic haemodynamics and renal blood flow and function in rats with liver failure

Protective Effects of the Third Generation Vasodilatory Βeta - Blocker Nebivolol against D-Galactosamine - Induced Hepatorenal Syndrome in Rats

BACKGROUND:

Renal dysfunction is very common in patients with advanced liver cirrhosis and portal hypertension. The development of renal failure in the absence of clinical, anatomical or pathological causes renal of failure is termed hepatorenal syndrome (HRS).

AIM:

The present study was constructed to investigate the possible protective effects of nebivolol (Nebi) against D-galactosamine (Gal)-induced HRS in rats.

MATERIAL AND METHODS:

Rats were treated with Nebi for ten successive days. On the 8th day of the experiment, they received a single dose of Gal. Serum levels of Cr, BUN, Na+ and K+ as well as AST, ALT, total bilirubin (TB), NH3 and endothelin-1 (ET-1) were determined following Gal administration. Moreover, renal and liver contents of MDA, GSH, F2-isoprostanes (F2-IPs), tumor necrosis factor-alpha (TNF-α), nuclear factor kappa-B (NF-κB), total nitric oxide (NO), in addition to activities of caspase-3 (Cas-3), heme oxygenase-1 (HO-1), inducible and endothelial NO synthase (iNOS and eNOS) enzymes were also assessed. Finally, histopathological examination was performed.

RESULTS:

Nebi attenuated Gal-induced renal and hepatic dysfunction. It also decreased the Gal-induced oxidative stress and inflammatory recruitment.

CONCLUSION:

Results demonstrated both nephroprotective and hepatoprotective effects of Nebi against HRS and suggested a role of its antioxidant, anti-inflammatory, anti-apoptotic and NO-releasing properties.

Effect of protocatechuic acid on lipid profile and DNA damage in D-galactosamine-induced hepatotoxic rats

BACKGROUND

Our aim in this study is to investigate the effect of protocatechuic acid (PCA) on lipid profile and DNA damage in D-galactosamine (D-GalN)-induced hepatotoxic rats.

METHODS

Hepatotoxicity was induced by a single intraperitoneal dose of D-GalN in male Wistar rats. The activities of hepatic markers and levels of kidney function markers were determined. The plasma and tissue lipid levels were estimated. DNA damage was determined by COMET assay. Histopathological examination was also performed using portions of the liver and kidney tissues.

RESULTS

D-GalN-induced hepatotoxic rats showed increased in the activities of hepatic marker enzymes such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and γ-glutamyl transpeptidase (GGT) in serum. The levels of kidney function markers such as urea, uric acid, and creatinine increased in serum. Levels of lipid profile such as total cholesterol (TC), triglycerides (TG), free fatty acid (FFA), and phospholipids (PLs) in the plasma and tissues (liver and kidney) were significantly increased in D-GalN-induced rats. In plasma, levels of very low density lipoprotein cholesterol (VLDL-C) and low-density lipoprotein cholesterol (LDL-C) significantly increased, whereas high-density lipoprotein cholesterol (HDL-C) level decreased in D-GalN-induced rats. Furthermore, D-GalN-induced rats showed increased percentage of tail DNA and tail length and decreased percentage of head DNA. Oral administration of PCA (100 mg/ kg BW) for 20 days improved these levels when compared to D-GalN-induced rats. These biochemical changes were reflected on the attenuation and the structural alteration of the liver and kidney integrity.

CONCLUSIONS

The results of the study suggest that PCA has a potent hepatoprotective activity that may be linked to its antihyperlipidemic effect.

Protective effects of ellagic acid in D-galactosamine-induced kidney damage in rats

D-Galactosamine (D-GalN), which is an established experimental toxin, primarily causes liver injury by the generation of free radicals and depletion of UTP nucleotides. D-GalN intoxication also induces renal dysfunction thus, renal failure is often associated with the end-stage of the liver damage. We have investigated both preventive and curative effects of ellagic acid (EA) in this study. EA treatment at a gavage dose of 20 mg/kg body weight was administered before and after intraperitoneal (i.p.) injection of D-GalN at a dose of 750 mg/kg. Tissue and blood samples of animals were collected for morphological and biochemical evaluations. Our study results suggest that EA treatment both prior to and after the toxin administration successfully altered the toxic effects on the rats. Moreover, pre-treatment of EA was more protective than post-treatment indicated by histopathological and biochemical values. In conclusion, EA treatment both before and after D-GalN intoxication could protect kidney tissues against D-GalN induced oxidative stress.

D-Galactosamine Intoxication in Experimental Animals: Is it Only an Experimental Model of Acute Liver Failure?

BACKGROUND

Short-term administration of Galactosamine to experimental animals causes liver damage and acute liver failure (ALF), as well as acute renal failure in some cases. The aim of our study was to describe kidney disorders that developed in the course of galactosamine-induced liver failure.

MATERIAL AND METHODS

Sprague-Dawley rats were randomly divided into 2 groups: a study group administered galactosamine intraperitoneally and a control group administered saline.

RESULTS

All the animals in the study group developed liver damage and failure within 48 h, with significant increase of alanine (p<0.001), aspartate aminotransferases (p<0.0001), bilirubin (p<0.004), and ammonia (p<0.005) and decrease of albumin (p<0.001) concentrations. Acute renal failure was observed in all test animals, with a significant increase in creatinine (p<0.001) and urea (p<0.001) concentrations and a decrease in creatinine clearance (p<0.0012). Moreover, osmotic clearance (p<0.001), daily natriuresis (p<0.003), and fractional sodium excretion (p<0.016) decreased significantly in this group of animals. The ratio of urine osmolality to serum osmolality did not change. Histopathology of the liver revealed massive necrosis of hepatocytes, whereas renal histopathology showed no changes.

CONCLUSIONS

Acute renal failure that developed in the course of galactosamine-induced ALF was of a functional nature, with the kidneys retaining the ability to concentrate urine and retain sodium, and there were no renal changes in the histopathological examination. It seems that the experimental model of ALF induced by galactosamine can be viewed as a model of hepatorenal syndrome that occurs in the course of acute damage and liver failure.

Hepatoprotective effect of nitric oxide in experimental model of acute hepatic failure

AIM: To evaluate the effect of nitric oxide (NO) on the development and degree of liver failure in an animal model of acute hepatic failure (AHF).

METHODS: An experimental rat model of galactosamine-induced AHF was used. An inhibitor of NO synthase, nitroarginine methyl ester, or an NO donor, arginine, were administered at various doses prior to or after the induction of AHF.

RESULTS: All tested groups developed AHF. Following inhibition of the endogenous NO pathway, most liver parameters improved, regardless of the inhibitor dose before the induction of liver damage, and depending on the inhibitor dose after liver damage. Prophylactic administration of the inhibitor was more effective in improving liver function parameters than administration of the inhibitor after liver damage. An attempt to activate the endogenous NO pathway prior to the induction of liver damage did not change the observed liver function parameters. Stimulation of the endogenous NO pathway after liver damage, regardless of the NO donor dose used, improved most liver function parameters.

CONCLUSION: The endogenous NO pathway plays an important role in the development of experimental galactosamine-induced AHF.

Hepatic and systemic hemodynamic derangements predict early mortality and recovery in patients with acute-on-chronic liver failure

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a clinical entity where there is a potential for reversibility of hepatic dysfunction once the acute hepatic insult resolves. The portal and systemic hemodynamics in ACLF patients to study its relevance in determining the clinical outcomes was studied.

METHODS

Clinical, laboratory, portal, and systemic hemodynamic assessments were done at admission and after 3 months. Standard medical care was given to all the patients.

RESULTS

Fifty-seven patients with ACLF were enrolled, and they underwent baseline hepatic venous pressure gradient (HVPG) measurement. Twenty-six (46%) patients died during the 3-month follow-up. Presence of high HVPG and hepatic encephalopathy were found to be independent baseline predictors of mortality. Of the 31 surviving patients, 24 consented for a repeat HVPG. The baseline HVPG reduced from 16 (range 12-30) to 13 (range 6-21) mmHg; (P < 0.05). The reduction in HVPG correlated with clinical and biochemical recovery, and reduction in Child-Turcotte-Pugh score score (P < 0.05), while the aortic mean arterial pressure, cardiac index and systemic vascular resistance index improved significantly (< 0.05). Six (25%) patients developed upper gastrointestinal bleed; the median HVPG between bleeders and non-bleeders was not different possibly because of early onset of bleed (median 20 [15-45 days]).

CONCLUSIONS

Baseline HVPG is an independent predictor of mortality in ACLF patients. The portal and systemic circulatory anomalies regress substantially by 90 days and correlate with clinical recovery. However, in the initial phase, the raised portal pressure predisposes these patients to high risk of variceal bleeding.

Brassica nigra plays a remedy role in hepatic and renal damage

CONTEXT

Black mustard [Brassica nigra (L.) Koch] of the Brassicaceae (Cruciferae) family is commonly used as a spice and a cheap source of antimicrobial agents for bacterial infections.

OBJECTIVES

The present investigation was to demonstrate the protective effect of the methanol extract of B. nigra leaves against D-galactosamine (D-GalN)-induced hepatic and nephrotoxicity in Wistar rats.

METHODS

Activity of the methanol extract of B. nigra at doses of 200 and 400 mg/kg b.wt. against D-GalN (500 mg/kg b.wt.) induced toxicity, with silymarin used as the standard. Histological damage, activities of serum marker enzyme, hematological changes, metabolites such as bilirubin, urea, uric acid, and creatinine levels, tissue thiobarbutric acid reactive substance, enzymic and non-enzymic antioxidants and inflammatory marker enzymes such as myeloperoxidase, cathepsin D, and acid phosphatase were assessed.

RESULTS

The D-GalN-induced toxicity was evident from a significant increase (p < 0.001) in the serum and tissue inflammatory markers in toxic rats, when compared with the control (saline alone treated animals). The B. nigra pretreated groups (200 and 400 mg/kg b.wt.) showed significant (p < 0.001) reduction in the D-GalN-induced toxicity as obvious from biochemical parameters. Histopathological observations confirm the protective effect of B. nigra leaf extract by reduction in hepatic and renal tissue damage. Experimentals extract showed a similar effect as the standard.

CONCLUSIONS

The crude methanol extract of B. nigra leaf lacks inherent toxicity and exhibits hepatic and nephroprotective effects against D-GalN-induced toxicity in Wistar rats.

Strain of experimental animals and modulation of nitric oxide pathway: their influence on development of renal failure in an experimental model of hepatorenal syndrome

INTRODUCTION

Pathomechanism of HRS is still poorly understood. The aim of our study was: (1) to test whether different strains of rats could develop typical HRS, and (2) to estimate the influence of activation and inhibition of nitric oxide for development of renal failure in course of HRS.

MATERIAL AND METHODS

First, we used 16 of Wistar and 16 of Sprague-Dawley rats in galactosamine model of HRS. Next, we used 48 of SDR rats, which received saline, N-nitro-L-arginine or L-arginine before and after liver damage. Twenty four hours urine and blood samples were collected 48 h after saline or Ga1N injection. Biochemical parameters were determined in serum or urine and then creatinine clearance and osmolality clearance were calculated. Liver and kidney tissues were collected for histopathological examination.

RESULTS

Liver failure developed in all tested groups with significant increase of bilirubin (p < 0.001), ALT (p < 0.001) and ammonia (p < 0.001). Nevertheless we did not achieve any evidence of renal failure in Wistar, but we found typical renal failure in Sprague-Dawley group with significant decrease in creatinine clearance (p < 0.0012) and increase in concentration of creatinine and urea (p < 0.001) and (p < 0.001) respectively. Inhibition of NOS prevented development of renal failure with significant improvement of GFR both before (p < 0.0017) and after (p < 0.003) Ga1N injection. Injection of L-arginine after Ga1N injection did not caused significant improvement of GFR.

CONCLUSIONS

Our study showed, that genetic factors might be responsible for development of renal failure in course of HRS and nitric oxide play important role in acute model of this syndrome.

Contrast-enhanced ultrasonography using Sonazoid to evaluate changes in hepatic hemodynamics in acute liver injury

BACKGROUND AND AIMS

Disturbances in hepatic microcirculation are believed to be involved in the mechanisms regulating the progression of acute liver injury (ALI). Evaluation of hepatic hemodynamics in patients with acute liver injury might be helpful in understanding the extent of the intrahepatic microcirculatory disturbances. Therefore, we investigated whether contrast-enhanced ultrasonography (CEUS) is useful to evaluate the changes in hepatic hemodynamics in patients with ALI.

METHODS

CEUS was performed in 21 patients with ALI and coagulopathy. Participants were injected with 0.0075 mL Sonazoid/kg body weight, and time-intensity curves were simultaneously recorded for the hepatic and portal veins. The data were compared with those of 10 healthy volunteers.

RESULTS

The arrival time of Sonazoid in the hepatic vein was similar to that in the portal vein in the patients, whereas the arrival time in the hepatic vein was delayed relative to that in the portal vain in the controls (interval between the hepatic and portal vein arrival times, control vs patients 6.74 ± 3.07 s vs 1.13 ± 1.07 s, P < 0.001). Repeated examination revealed that the interval between the hepatic and portal vein arrival times was extended by improvements in hepatic function. The early arrival of Sonazoid in the hepatic vein in the patients is likely to reflect the formation of intrahepatic shunts as a result of hepatic microcirculatory disturbances.

CONCLUSION

CEUS using Sonazoid is a useful method to estimate the changes in hepatic hemodynamics in patients with ALI.

A real-time, telemetric method for continuous measurement of portal pressures

The ability to longitudinally monitor portal and splanchnic pressures would greatly enhance the understanding of acute and chronic liver disease by helping to assess the immediate and long-term impact of therapeutic manipulations. However, a technique for measuring portal pressures in the ambulatory setting is not currently available. To overcome this difficulty, we utilized an approach that involved the implantation of a miniature telemetric device, equipped with a specially-designed pressure transmission catheter, into the spleen of an anesthetized mouse. Using this approach, portal pressures were measured continuously over 5 d in conscious, unrestrained animals, the availability of which will help facilitate studies of the portal circulation requiring long-term stability.

Hemodynamic studies in acute-on-chronic liver failure

BACKGROUND

Patients with decompensated cirrhosis and acute liver failure have circulatory dysfunctions leading to high portal pressure and cardiac output (CO) and low systemic vascular resistance (SVR). Circulatory changes in acute-on-chronic liver failure (ACLF) patients have not been studied. We studied the portal, systemic, and pulmonary hemodynamics in patients with ACLF and compared them with compensated and decompensated cirrhotics.

PATIENTS AND METHODS

Clinical features and hemodynamic profile were studied in patients with ACLF and compared with age- and sex-matched compensated and decompensated cirrhotics with portal hypertension.

RESULTS

The study cohort comprised 144 patients categorized into one of three groups (ACLF, compensated cirrhosis, and decompensated cirrhosis), with 48 (33%) patients in each group. All values are given as the mean +/- standard deviation, except for frequencies (%). The mean arterial pressure (MAP) and SVR were lower in the ACLF than the compensated group and were similar to those of the decompensated group (MAP 90 +/- 16 vs. 99 +/- 15 vs. 96 +/- 16 mmHg; SVR 912 +/- 435 vs. 1350 +/- 449 vs. 891 +/- 333 dyn s/cm(5)). The mean CO of the ACLF patients was higher than that of the compensated group and similar to that of the decompensated group (CO 8.9 +/- 3.5 vs. 6.1 +/- 1.7 vs. 9.0 +/- 3.0 l/min). The pulmonary vascular resistance (PVR) and pulmonary capillary wedge pressures (PCWP) were similar in all the three groups (PVR 78 +/- 48 vs. 109 +/- 70 vs. 61 +/- 47 dyn s/cm(5); PCWP 8 +/- 4 vs. 8 +/- 4 vs. 10 +/- 5 mmHg). The mean hepatic venous pressure gradient (HVPG) in the ACLF group was 15.1 +/- 6.3 mmHg, which was significantly higher than that of the compensated group (11.7 +/- 6.3 mmHg), but lower than that of the decompensated cirrhosis group (20.2 +/- 6.0 mmHg). When patients of ACLF were categorized on the basis of their variceal size, the mean HVPG in ACLF patients with small varices was similar to that of compensated cirrhotics (13.7 +/- 5.7 vs. 11.7 +/- 6.3 mmHg; P = 0.146), while in the ACLF patients with large varices, the HVPG was comparable to that of the decompensated cirrhotics (18.7 +/- 6.6 vs. 20.2 +/- 6.0 mmHg; P = 0.442).

CONCLUSIONS

The systemic hemodynamics in patients with ACLF is similar to that in decompensated cirrhotics. The portal pressure in these patients is higher than that in the compensated cirrhotics, and in the subgroup with large varices, it becomes similar to that of decompensated cirrhotics.

Cerebral blood flow autoregulation in experimental liver failure

Patients with acute liver failure (ALF) display impairment of cerebral blood flow (CBF) autoregulation, which may contribute to the development of fatal intracranial hypertension, but the pathophysiological mechanism remains unclear. In this study, we examined whether loss of liver mass causes impairment of CBF autoregulation. Four rat models were chosen, each representing different aspects of ALF: galactosamine (GlN) intoxication represented liver necrosis, 90% hepatectomy (PHx90) represented reduction in liver mass, portacaval anastomosis (PCA) represented shunting of blood/toxins into the systemic circulation thus mimicking intrahepatic shunting in ALF, PCA+NH(3) provided information about the additional effects of hyperammonemia Rats were intubated and sedated with pentobarbital. We measured CBF with laser Doppler, intracranial pressure (ICP) was measured in the fossa posterior and registered with a pressure transducer, brain water was measured using the wet-to-dry method, and cerebral glutamine/glutamate was measured enzymatically. The CBF autoregulatory index in both the GlN and PHx90 groups differed significantly from the control group. Conversely, CBF autoregulation was intact in the PCA and PCA+NH(3) groups despite high arterial ammonia, high cerebral glutamine concentration, and increased CBF and ICP. Increased water content of the brainstem or cerebellum was not associated with defective CBF autoregulation. In conclusion, impairment of CBF autoregulation is not caused by brain edema/high ICP. Nor does portacaval shunting or hyperammonemia impair autoregulation. Rather, massive liver necrosis and reduced liver mass are associated with loss of CBF autoregulation.

Amelioration of galactosamine-induced nephrotoxicity by a protein isolated from the leaves of the herb, Cajanus indicus L

BACKGROUND

Galactosamine (GalN), an established experimental toxin, mainly causes liver injury via the generation of free radicals and depletion of UTP nucleotides. Renal failure is often associated with end stage liver damage. GalN intoxication also induces renal dysfunction in connection with hepatic disorders. Present study was designed to find out the effect of a protein isolated from the leaves of the herb Cajanus indicus against GalN induced renal damage.

METHODS

Both preventive as well as curative effect of the protein was investigated in the study. GalN was administered intraperitoneally at a dose of 800 mg/kg body weight for 3 days pre and post to protein treatment at an intraperitoneal dose of 2 mg/kg body weight for 4 days. The activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST), levels of cellular metabolites, reduced glutathione (GSH), total thiols, oxidized glutathione (GSSG) and lipid peroxidation end products were determined to estimate the status of the antioxidative defense system. In addition, serum creatinine and urea nitrogen (UN) levels were also measured as a marker of nephrotoxicity.

RESULTS

Results showed that GalN treatment significantly increased the serum creatinine and UN levels compared to the normal group of mice. The extent of lipid peroxidation and the level of GSSG were also enhanced by the GalN intoxication whereas the activities of antioxidant enzymes SOD, CAT, GR and GST as well as the levels of total thiols and GSH were decreased in the kidney tissue homogenates. Protein treatment both prior and post to the toxin administration successfully altered the effects in the experimental mice.

CONCLUSION

Our study revealed that GalN caused a severe oxidative insult in the kidney. Protein treatment both pre and post to the GalN intoxication could protect the kidney tissue against GalN induced oxidative stress. As GalN induced severe hepatotoxicity followed by renal failure, the protective role of the protein against GalN induced renal damages is likely to be an indirect effect. Since the protein possess hepatoprotective activity, it may first ameliorate GalN-induced liver damage and consequently the renal disorders are reduced. To the best of our knowledge, this is probably the first report describing GalN-induced oxidative stress in renal damages and the protective role of a plant protein molecule against it.

Systemic and regional hemodynamics in pigs with acute liver failure and the effect of albumin dialysis

OBJECTIVE

Acute liver failure (ALF) is haemodynamically characterized by a hyperdynamic circulation. The aims of this study were to investigate the systemic and regional haemodynamics in ALF, to measure changes in nitric oxide metabolites (NOx) and to evaluate whether these haemodynamic disturbances could be attenuated with albumin dialysis.

MATERIAL AND METHODS

Norwegian Landrace pigs (23-30 kg) were randomly allocated to groups as controls (sham-operation, n = 8), ALF (hepatic devascularization, n = 8) and ALF + albumin dialysis (n = 8). Albumin dialysis was started 2 h after ALF induction and continued for 4 h. Systemic and regional haemodynamics were monitored. Creatinine clearance, nitrite/nitrate and catecholamines were measured. A repeated measures ANOVA was used to analyse the data.

RESULTS

In the ALF group, the cardiac index increased (PGT < 0.0001), while mean arterial pressure (PG = 0.02) and systemic vascular resistance decreased (PGT < 0.0001). Renal resistance (PG = 0.04) and hind-leg resistance (PGT = 0.003) decreased in ALF. There was no difference in jejunal blood flow between the groups. ALF pigs developed renal dysfunction with increased serum creatinine (PGT = 0.002) and decreased creatinine clearance (P = 0.02). Catecholamines were significantly higher in ALF, but NOx levels were not different. Albumin dialysis did not attenuate these haemodynamic or renal disturbances.

CONCLUSIONS

The haemodynamic disturbances during the early phase of ALF are characterized by progressive systemic vasodilatation with no associated changes in metabolites of NO. Renal vascular resistance decreased and renal dysfunction developed independently of changes in renal blood flow. After 4 h of albumin dialysis there was no attenuation of the haemodynamic or renal disturbances.

Contribution of hepatic adenosine A1 receptors to renal dysfunction associated with acute liver injury in rats

Acute liver injury is associated with renal insufficiency, whose mechanism may be related to activation of the hepatorenal reflex. We previously showed that intrahepatic adenosine is involved in activation of the hepatorenal reflex to restrict urine production in both healthy rats and in rats with cirrhosis. The aim of the present study was to test the hypothesis that activation of intrahepatic adenosine receptors is involved in the pathogenesis of the renal insufficiency seen in acute liver injury. Acute liver injury was induced by intraperitoneal injection of thioacetamide (TAA, 500 mg/kg) in rats. The animals were instrumented 24 hours later to monitor systemic, hepatic, and renal circulation and urine production. Severe liver injury developed following TAA insult, which was associated with renal insufficiency, as demonstrated by decreased (approximately 25%) renal arterial blood flow, a lower (approximately 30%) glomerular filtration rate, and decreased urine production. Further, the increase in urine production following volume expansion challenge was inhibited. Intraportal, but not intravenous, administration of a nonselective adenosine receptor antagonist, 8-phenyltheophylline, improved urine production. To specify receptor subtype, the effects of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, an adenosine A(1) receptor antagonist) and 3,7-dimethyl-1-propargylxanthine (DMPX, an adenosine A(2) receptor antagonist) were compared. Intraportal but not intravenous administration of DPCPX greatly improved impaired renal function induced by acute liver injury, and this beneficial effect was blunted in rats with liver denervation. In contrast, neither intraportal nor intravenous administration of DMPX showed significant improvement in renal function. In conclusion, an activated hepatorenal reflex, triggered by intrahepatic adenosine A(1) receptors, contributed to the pathogenesis of the water and sodium retention associated with acute liver injury.

Salvage effect of the vascular endothelial growth factor on chemically induced acute severe liver injury in rats

BACKGROUND/AIMS

The role of the vascular endothelial growth factor (VEGF), a potent angiogenic factor, in liver regeneration following acute severe liver injury (ALI) has not been elucidated. The aims of the current study were to investigate the role of VEGF, and to find out whether VEGF can improve the outcome of ALI in rats.

METHODS

ALI was induced in male rats by combination of D-galactosamine (Gal-N) and lipopolysaccharide (LPS). The survival rate and several indices were chronologically compared with or without VEGF treatment.

RESULTS

The overall survival rate of the VEGF-treated group significantly improved as compared with the untreated group (100 vs. 27%, respectively). The serum ALT elevation, with a peak at 24 h after Gal-N+LPS intoxication, was markedly attenuated with VEGF treatment. The proliferation of hepatocytes and sinusoidal endothelial cells (SEC) was stimulated by VEGF with a peak at 36 and 96 h, respectively. The immunohistochemical analysis revealed that VEGF drastically prevented destruction of the SEC architecture in ALI. Our in vitro study showed that VEGF significantly prevented the Gal-N+LPS-induced cytotoxicity and apoptosis of SEC.

CONCLUSIONS

VEGF treatment significantly reduced the mortality rate of ALI in the rat, and it may provide a new therapeutic strategy for ALI.

Results of L-[1-13C]phenylalanine breath test with air isotope ratio mass spectrometry can reflect the activity of phenylalanine hydroxylase in cirrhotic rat liver

The L-[1-13C]phenylalanine breath test (PheBT) could potentially advance the evaluation of hepatocyte function and liver functional reserve. However, because the factors influencing PheBT results have not been clarified, the clinical application of the test has been limited. This study investigated the relationship between the parameters of PheBT, performed with air isotope ratio mass spectrometry, and the activity of phenylalanine hydroxylase (PAH), the phenylalanine metabolism rate-limiting enzyme, in rat liver, and proposes valid parameters for the assessment of liver function. Chronic injury to the liver was induced by the administration of CCl4 to male Sprague-Dawley rats for either 8 or 12 weeks. Livers from rats in the two cirrhotic groups were discolored, enlarged and roughly textured, with cells filled with fat granules of various sizes, pseudolobuli formations, and regenerated tubercles. Of the 12 parameters tested, only the unit liver weight (LW) breath test parameters, including the maximum abundance of 13C in breath (13Cmax/LW), 13C abundance in breaths 2 and 7 min after administration of L-[1-(13)C]phenylalanine (13C-phe) (13C2/LW and 13C7/LW), cumulative 13C excretion 10 and 30 min after 13C-phe administration (AUC10/LW and AUC30/LW), and the 13C excretion rate constant (PheBT-k/LW) were significantly affected in the chronic liver injury groups. There was no significant difference in the total PAH activity in liver among the three groups, but there was significant difference in unit LW PAH activity. Total PAH activity in the liver was significantly correlated with 13Cmax, 13C2, 13C7, AUC10, AUC30 and PheBT-k, while the unit LW PAH activity was significantly correlated with 13Cmax/LW, 13C2/LW, 13C7/LW, AUC10/LW, AUC30/LW and PheBT-k/LW. PheBT-k/LW was also correlated with biochemical indices that are used to assess liver function. The present findings indicate that the PheBT results based on air isotope ratio mass spectrometry can quantitatively reflect the change in total PAH activity in the livers of chronically injured rats. PheBT-k and PheBT-k/LW are the most sensitive among the test parameters, and can be used to assess liver functional reserve and hepatocyte damage at the molecular level.

Alterations of the renal function and oxidative stress in renal tissue from rats chronically treated with aluminium during the initial phase of hepatic regeneration

Various indices of renal functions during the early stage of hepatic injury were studied in rats chronically treated with aluminum (Al) lactate. Tubular and hemodynamic parameters were analyzed four days after producing a 65% partial hepatectomy (PH). Water and sodium balances were also studied. Oxidative stress and the activity of Na-K-ATPase were determined in renal tissue. The rats were distributed in four groups: control, Al, PH, Al+PH. Al did not modify the hemodynamic renal functions and the PH-group reduced the glomerular filtrate rate (GFR). The Al + PH group presented a decrease in the renal blood flow and accentuated the GFR fall as compared with PH. The fractional excretion (FE) of water and sodium increased in the PH group. The rats chronically treated with Al and then submitted to the PH protocol developed a further increase in FE of water but a reduction in FE of sodium. Both PH and Al promoted an increase in the aldosterone. PH and Al induced a similar increase of the lipoperoxidation status with reduction of glutathione (GSH) and the activity of glutathione peroxidase (GSH-Px). The data indicated that Al is an inhibitor of catalase. The GSH and GSH-Px activity in the Al + PH group demonstrated a synergic effect of Al and PH. This work demonstrates that rats treated chronically with Al and submitted to another injury (such as hepatic damage) can aggravate renal functions, probably by increasing the oxidative state, at least in kidneys.

Eicosanoids in cirrhosis and portal hypertension

In the last decade, the knowledge of the pathogenesis of portal hypertension and cirrhosis has increased dramatically. In portal hypertension, almost all the known vasoactive systems/substances are activated or increased and the most recent studies have stressed the importance of the endothelial factors, in particular, prostaglandins. Prostaglandins are formed following the oxygenation of arachidonic acid by the cyclooxygenase (Cox) pathway. An important consideration in portal hypertension and cirrhosis in the periphery is the altered hemodynamic profile and its contributory role in controlling endothelial release of these vasoactive substances. Prostaglandins are released from the endothelium in response to both humoral and mechanical stimuli and can profoundly affect both intrahepatic and peripheral vascular resistance. Within the liver, intrahepatic resistance is altered due to a diminution in sinusoidal responsiveness to vasodilators and an increase in prostanoid vasoconstrictor responsiveness. This review will examine the contributory role of both hormonal and/or hemodynamic force-induced changes in prostaglandin production and signaling in cirrhosis and portal hypertension and the consequence of these changes on the structural and functional response of both the vasculature and the liver.

Endothelin is an important determinant of renal function in a rat model of acute liver and renal failure

BACKGROUND AND AIMS

Renal failure occurs in approximately 55% of patients with acute liver failure. We have previously shown that plasma endothelin 1 concentrations are elevated in patients with acute liver failure and the hepatorenal syndrome. There are few reported satisfactory animal models of liver failure together with functional renal failure. In this study, a rat model of acute liver failure induced by galactosamine that also develops renal failure was first characterised. This model was used to investigate the hypothesis that endothelin 1 is an important mediator involved in the pathogenesis of renal impairment that occurs in acute liver failure.

METHODS

Acute liver failure was induced in male Sprague-Dawley rats by intraperitoneal injection of galactosamine together with treatment with the endothelin receptor antagonist Bosentan. Twenty four hour urine collections were made using a metabolic cage. Renal blood flow was measured in anaesthetised animals.

RESULTS

This model developed renal failure and liver failure in the absence of any significant renal pathology, and with an accompanying fall in renal blood flow. Plasma concentrations of endothelin 1 were increased twofold following the onset of liver and renal failure (p<0.05), and there was significant upregulation of the endothelin receptor A (ET(A)) in the renal cortex (p<0.05). Administration of Bosentan prevented the development of renal failure when given before or 24 hours after the onset of liver injury (p<0.05) but had no effect on liver injury itself, or on renal blood flow.

CONCLUSIONS

This study demonstrates that this animal model has many of the features needed to be regarded as a model of renal failure that occurs in acute liver failure. The observation that plasma levels of endothelin 1 and ET(A) receptors are increased and upregulated, and that renal failure is prevented by an endothelin antagonist supports the hypothesis originally put forward that ET(A) is important in the pathogenesis of renal failure that occurs in patients with acute liver failure.

Laboratory assessment of hepatic hemodynamics

Although the study of hepatic circulation is complicated by the dual blood supply and complex anatomy of the liver, many distinct methods are available to facilitate its study. Before embarking on an investigation of hepatic hemodynamics, the investigator must be familiar with the available methods and their applications. All methods have their own attributes and limitations. No one method is superior to the others, but, depending on the aspect of hepatic hemodynamics to be investigated, a particular methodology may yield distinct advantages.

TNF-alpha dependent production of inducible nitric oxide is involved in PGE(1) protection against acute liver injury

BACKGROUND

Tumour necrosis factor alpha (TNF-alpha) and nitric oxide modulate damage in several experimental models of liver injury. We have previously shown that protection against D-galactosamine (D-GalN) induced liver injury by prostaglandin E(1) (PGE(1)) was accompanied by an increase in TNF-alpha and nitrite/nitrate in serum.

AIMS

The aim of the present study was to evaluate the role of TNF-alpha and nitric oxide during protection by PGE(1) of liver damage induced by D-GalN.

METHODS

Liver injury was induced in male Wistar rats by intraperitoneal injection of 1 g/kg of D-GalN. PGE(1) was administered 30 minutes before D-GalN. Inducible nitric oxide synthase (iNOS) was inhibited by methylisothiourea (MT), and TNF-alpha concentration in serum was lowered by administration of anti-TNF-alpha antibodies. Liver injury was evaluated by alanine aminotransferase activity in serum, and histological examination and DNA fragmentation in liver. TNF-alpha and nitrite/nitrate concentrations were determined in serum. Expression of TNF-alpha and iNOS was also assessed in liver sections.

RESULTS

PGE(1) decreased liver injury and increased TNF-alpha and nitrite/nitrate concentrations in serum of rats treated with D-GalN. PGE(1) protection was related to enhanced expression of TNF-alpha and iNOS in hepatocytes. Administration of anti-TNF-alpha antibodies or MT blocked the protection by PGE(1) of liver injury induced by D-GalN.

CONCLUSIONS

This study suggests that prior administration of PGE(1) to D-GalN treated animals enhanced expression of TNF-alpha and iNOS in hepatocytes, and that this was causally related to protection by PGE(1) against D-GalN induced liver injury.