Hepatic Vascular Bed Research Articles

Portal Hemodynamics in Liver Resection and Transplantation.

The hepatic blood supply and its several homeostatic and pathologic processes has always been a matter of great interest. Many views commonly held today are derived from an earlier era, but major reorientations have occurred recently in almost all aspects of knowledge of the role and regulation of hepatic blood flow. Moreover, with the advent of liver transplantation (LT), especially living donor LT (LDLT) there has been a resurgence of interest in attempting to comprehend this deceptively simple topic. It is nonetheless important to concede that even though our knowledge on the practical modulation of hepatic hemodynamics has expanded enormously, there still remain the need to explore the depths of our remaining ignorance to further improve outcomes in LDLT. This review focuses on the current view, controversies and gaps in knowledge of the hepatic vascular bed, with an emphasis on the importance of portal hemodynamics in liver disease and its impact on liver regeneration and LT.

Cirrhotic portal hypertension: From pathophysiology to novel therapeutics.

Portal hypertension and bleeding from gastroesophageal varices is the major cause of morbidity and mortality in patients with cirrhosis. Portal hypertension is initiated by increased intrahepatic vascular resistance and a hyperdynamic circulatory state. The latter is characterized by a high cardiac output, increased total blood volume and splanchnic vasodilatation, resulting in increased mesenteric blood flow. Pharmacological manipulation of cirrhotic portal hypertension targets both the splanchnic and hepatic vascular beds. Drugs such as angiotensin converting enzyme inhibitors and angiotensin II type receptor 1 blockers, which target the components of the classical renin angiotensin system (RAS), are expected to reduce intrahepatic vascular tone by reducing extracellular matrix deposition and vasoactivity of contractile cells and thereby improve portal hypertension. However, these drugs have been shown to produce significant off-target effects such as systemic hypotension and renal failure. Therefore, the current pharmacological mainstay in clinical practice to prevent variceal bleeding and improving patient survival by reducing portal pressure is non-selective -blockers (NSBBs). These NSBBs work by reducing cardiac output and splanchnic vasodilatation but most patients do not achieve an optimal therapeutic response and a significant proportion of patients are unable to tolerate these drugs. Although statins, used alone or in combination with NSBBs, have been shown to improve portal pressure and overall mortality in cirrhotic patients, further randomized clinical trials are warranted involving larger patient populations with clear clinical end points. On the other hand, recent findings from studies that have investigated the potential use of the blockers of the components of the alternate RAS provided compelling evidence that could lead to the development of drugs targeting the splanchnic vascular bed to inhibit splanchnic vasodilatation in portal hypertension. This review outlines the mechanisms related to the pathogenesis of portal hypertension and attempts to provide an update on currently available therapeutic approaches in the management of portal hypertension with special emphasis on how the alternate RAS could be manipulated in our search for development of safe, specific and effective novel therapies to treat portal hypertension in cirrhosis.

Hepatorenal syndrome in children: a review.

Hepatorenal syndrome (HRS) occurs in patients with cirrhosis or fulminant hepatic failure and is a kind of pre-renal failure due to intense reduction of kidney perfusion induced by severe hepatic injury. While other causes of pre-renal acute kidney injury (AKI) respond to fluid infusion, HRS does not. HRS incidence is 5% in children with chronic liver conditions before liver transplantation. Type 1 HRS is an acute and rapidly progressive form that often develops after a precipitating factor, including gastrointestinal bleeding or spontaneous bacterial peritonitis, while type 2 is considered a slowly progressive form of kidney failure that often occurs spontaneously in chronic ascites settings. HRS pathogenesis is multifactorial. Cirrhosis causes portal hypertension; therefore, stasis and release of vasodilator substances occur in the hepatic vascular bed, leading to vasodilatation of splanchnic arteries and systemic hypotension. Many mechanisms seem to work together to cause this imbalance: splanchnic vasodilatation; vasoactive mediators; hyperdynamic circulation states and subsequent cardiac dysfunction; neuro-hormonal mechanisms; changes in sympathetic nervous system, renin-angiotensin system, and vasopressin. In patients with AKI and cirrhosis, fluid expansion therapy needs to be initiated as soon as possible and nephrotoxic drugs discontinued. Once HRS is diagnosed, pharmacological treatment with vasoconstrictors, mainly terlipressin plus albumin, should be initiated. If there is no response, other options can include surgical venous shunts and kidney replacement therapy. In this regard, extracorporeal liver support can be a bridge for liver transplantation, which remains as the ideal treatment. Further studies are necessary to investigate early biomarkers and alternative treatments for HRS.

Portal hyperperfusion after major liver resection and associated sinusoidal damage is a therapeutic target to protect the remnant liver.

Extended liver resection results in loss of a large fraction of the hepatic vascular bed, thereby causing abrupt alterations in perfusion of the remnant liver. Mechanisms of hemodynamic adaptation and associated changes in oxygen metabolism after liver resection and the effect of mechanical portal blood flow reduction were assessed. A pig model (n = 16) of extended partial hepatectomy was established that included continuous observation for 24 h under general anesthesia. Pigs were randomly separated into two groups, one with a portal flow reduction of 70% compared with preoperative values, and the other as a control (n = 8, each). In controls, portal flow [mean (SD)] increased from 74 (8) mL·min-1·100 g-1 preoperatively to 240 (48) mL·min-1·100 g-1 at 6 h after resection (P < 0.001). Hepatic arterial buffer response was abolished after resection. Oxygen uptake per unit liver mass increased from 4.0 (1.1) mL·min-1·100 g-1 preoperatively to 7.7 (1.7) mL·min-1·100 g-1 8 h after resection (P = 0.004). Despite this increase in relative oxygen uptake, total hepatic oxygen consumption (V̇o2) was not maintained, and markers of hypoxia and anaerobic metabolism were significantly increased in hepatocytes after resection. Reduced postoperative portal flow was associated with significantly decreased levels of aspartate aminotransferase and bilirubin and increased hepatic clearance of indocyanine green. In conclusion, major liver resection was associated with persistent portal hyperperfusion, loss of the hepatic arterial buffer response, decreased total hepatic V̇o2 and with increased anaerobic metabolism. Portal flow modulation by partial portal vein occlusion attenuated liver injury after extended liver resection.NEW & NOTEWORTHY Because of continuous monitoring, the experiments allow precise observation of the influence of liver resection on systemic and local abdominal hemodynamic alterations and oxygen metabolism. Major liver resection is associated with significant and persistent portal hyperperfusion and loss of hepatic arterial buffer response. The correlation of portal hyperperfusion and parameters of liver injury and dysfunction offers a novel therapeutic option to attenuate liver injury after extended liver resection.

Cirrhosis and Complications of Portal Hypertension

Cirrhosis is the most advanced stage of all the different types of chronic liver diseases. It is defined as a diffuse disorganization of normal hepatic structure by extensive fibrosis associated with regenerative nodules. Hepatic fibrosis is potentially reversible if the causative agent is removed. However, advanced cirrhosis leads to major alterations in the hepatic vascular bed and is usually irreversible. Cirrhosis is a progressive and severe clinical condition associated with considerable morbidity and high mortality. It leads to a wide spectrum of characteristic clinical manifestations, mainly attributable to hepatic insufficiency and portal hypertension. Major complications of portal hypertension include ascites, gastrointestinal (GI) variceal bleeding, hepatic encephalopathy (HE), renal failure, and bacterial infections. In recent years, major advances in the understanding of the natural history and pathophysiology of cirrhosis and the treatment of its complications have led to improved management, quality of life, and life expectancy of patients with this disease. Cirrhosis is also a risk factor for developing hepatocellular carcinoma (HCC). Decompensated cirrhosis carries a poor short-term prognosis; thus, orthotopic liver transplantation (OLT) should always be considered in suitable candidates. This chapter describes the epidemiology, etiology and genetic factors, pathogenesis, diagnosis, general management, and treatment of cirrhosis. Complications of cirrhosis are discussed, including ascites, spontaneous bacterial peritonitis, dilutional hyponatremia, hepatorenal syndrome, variceal bleeding, hepatopulmonary syndrome and postpulmonary hypertension, HE, and HCC. Indications and contraindications for liver transplantation are described. Figures show liver biopsy results and ultrasound images in cirrhosis from hepatitis C, a patient with tense ascites, transjugular intrahepatic portosystemic shunting (TIPS), large esophageal varices with red spots, and HCC. Tables outline the main causes of cirrhosis and the diagnostic methods for identifying them, the Child-Pugh score, diagnostic criteria for hepatorenal syndrome, grades of HE, and indications for liver transplantation.This chapter contains 6 highly rendered figures, 8 tables, 73 references.

Cirrhosis and Complications of Portal Hypertension

Cirrhosis is the most advanced stage of all the different types of chronic liver diseases. It is defined as a diffuse disorganization of normal hepatic structure by extensive fibrosis associated with regenerative nodules. Hepatic fibrosis is potentially reversible if the causative agent is removed. However, advanced cirrhosis leads to major alterations in the hepatic vascular bed and is usually irreversible. Cirrhosis is a progressive and severe clinical condition associated with considerable morbidity and high mortality. It leads to a wide spectrum of characteristic clinical manifestations, mainly attributable to hepatic insufficiency and portal hypertension. Major complications of portal hypertension include ascites, gastrointestinal (GI) variceal bleeding, hepatic encephalopathy (HE), renal failure, and bacterial infections. In recent years, major advances in the understanding of the natural history and pathophysiology of cirrhosis and the treatment of its complications have led to improved management, quality of life, and life expectancy of patients with this disease. Cirrhosis is also a risk factor for developing hepatocellular carcinoma (HCC). Decompensated cirrhosis carries a poor short-term prognosis; thus, orthotopic liver transplantation (OLT) should always be considered in suitable candidates. This chapter describes the epidemiology, etiology and genetic factors, pathogenesis, diagnosis, general management, and treatment of cirrhosis. Complications of cirrhosis are discussed, including ascites, spontaneous bacterial peritonitis, dilutional hyponatremia, hepatorenal syndrome, variceal bleeding, hepatopulmonary syndrome and postpulmonary hypertension, HE, and HCC. Indications and contraindications for liver transplantation are described. Figures show liver biopsy results and ultrasound images in cirrhosis from hepatitis C, a patient with tense ascites, transjugular intrahepatic portosystemic shunting (TIPS), large esophageal varices with red spots, and HCC. Tables outline the main causes of cirrhosis and the diagnostic methods for identifying them, the Child-Pugh score, diagnostic criteria for hepatorenal syndrome, grades of HE, and indications for liver transplantation.This chapter contains 6 highly rendered figures, 8 tables, 73 references.

Cirrhosis and Complications of Portal Hypertension

Cirrhosis is the most advanced stage of all the different types of chronic liver diseases. It is defined as a diffuse disorganization of normal hepatic structure by extensive fibrosis associated with regenerative nodules. Hepatic fibrosis is potentially reversible if the causative agent is removed. However, advanced cirrhosis leads to major alterations in the hepatic vascular bed and is usually irreversible. Cirrhosis is a progressive and severe clinical condition associated with considerable morbidity and high mortality. It leads to a wide spectrum of characteristic clinical manifestations, mainly attributable to hepatic insufficiency and portal hypertension. Major complications of portal hypertension include ascites, gastrointestinal (GI) variceal bleeding, hepatic encephalopathy (HE), renal failure, and bacterial infections. In recent years, major advances in the understanding of the natural history and pathophysiology of cirrhosis and the treatment of its complications have led to improved management, quality of life, and life expectancy of patients with this disease. Cirrhosis is also a risk factor for developing hepatocellular carcinoma (HCC). Decompensated cirrhosis carries a poor short-term prognosis; thus, orthotopic liver transplantation (OLT) should always be considered in suitable candidates. This chapter describes the epidemiology, etiology and genetic factors, pathogenesis, diagnosis, general management, and treatment of cirrhosis. Complications of cirrhosis are discussed, including ascites, spontaneous bacterial peritonitis, dilutional hyponatremia, hepatorenal syndrome, variceal bleeding, hepatopulmonary syndrome and postpulmonary hypertension, HE, and HCC. Indications and contraindications for liver transplantation are described. Figures show liver biopsy results and ultrasound images in cirrhosis from hepatitis C, a patient with tense ascites, transjugular intrahepatic portosystemic shunting (TIPS), large esophageal varices with red spots, and HCC. Tables outline the main causes of cirrhosis and the diagnostic methods for identifying them, the Child-Pugh score, diagnostic criteria for hepatorenal syndrome, grades of HE, and indications for liver transplantation.This chapter contains 6 highly rendered figures, 8 tables, 73 references.

Hipertensión pulmonar como manifestación de la telangiectasia hemorrágica hereditaria o síndrome de Osler-Weber-Rendu

La telangiectasia hemorrágica hereditaria o síndrome de Osler-Weber-Rendu, es una enfermedad infrecuente, cuya prevalencia estimada es de entre 1:5.000 y 1:8.000 personas. Existen tasas más elevadas en ciertas áreas geográficas como Curazao y Bonaire, pero no es posible definir con exactitud las estadísticas debido al desconocimiento de la enfermedad en la mayoría de los pacientes que la padecen. Es un trastorno autosómico dominante con penetrancia variable que se caracteriza por epistaxis, telangiectasias y malformaciones vasculares en distintos territorios, tales como pulmonar, gastrointestinal, hepático y cerebral.

Caffeine ameliorates hemodynamic derangements and portosystemic collaterals in cirrhotic rats.

Portal hypertension (PH), a pathophysiological derangement of liver cirrhosis, is characterized by hyperdynamic circulation, angiogenesis, and portosystemic collaterals. These may lead to lethal complications, such as variceal bleeding. Caffeine has been noted for its effects on liver inflammation, fibrogenesis, and vasoreactiveness. However, the relevant influences of caffeine in cirrhosis and PH have not been addressed. Spraque-Dawley rats with common bile duct ligation-induced cirrhosis or sham operation received prophylactic or therapeutic caffeine treatment (50 mg/kg/day, the first or 15th day since operation, respectively) for 28 days. Compared to vehicle (distilled water), caffeine decreased cardiac index, increased systemic vascular resistance, reduced portal pressure (PP), superior mesenteric artery flow, mesenteric vascular density, portosystemic shunting (PSS), intrahepatic angiogenesis, and fibrosis without affecting liver and renal biochemistry. The beneficial effects were reversed by selective adenosine A1 agonist N6-cyclopentyladenosine (CPA) or A2A agonist GCS21680. Both prophylactic and therapeutic caffeine treatment decreased portal resistance and PP in thioacetamide (200mg/kg, thrice-weekly for 8 weeks)-induced cirrhotic rats. Caffeine down-regulated endothelial nitric oxide synthase, vascular endothelial growth factor (VEGF), phospho-VEGFR2, and phospho-Akt mesenteric protein expression. Caffeine adversely affected viability of hepatic stellate and sinusoidal endothelial cells, which was reversed by CPA and GCS21680. On the other hand, caffeine did not modify vascular response to vasoconstrictors in splanchnic, hepatic, and collateral vascular beds. Caffeine decreased PP, ameliorated hyperdynamic circulation, PSS, mesenteric angiogenesis, hepatic angiogenesis, and fibrosis in cirrhotic rats. Caffeine may be a feasible candidate to ameliorate PH-related complications in cirrhosis.

The responses of the hepatic and splanchnic vascular beds to vasopressin in rats

Vasopressin, a vasoactive peptide, causes vasoconstriction via V1a vasopressin receptors. Unlike other vasoconstrictor agents, vasopressin also has vasodilatory properties. The purpose of this study was to determine the effect of vasopressin on hepatic and splanchnic circulation in Sprague- Dawley rats. The experiments were conducted in not only isolated blood- and constant flowperfused livers but also anesthetized spontaneously breathing rats. In anesthetized rats, portal venous pressure (Ppv), systemic arterial pressure (Psa), central venous pressure, and hepatic blood flow (HBF) of combined portal venous and hepatic arterial blood flow were continuously measured, and splanchnic vascular bed resistance (Rspl) defined by (Psa - Ppv) / HBF was determined. In perfused livers, vasopressin at 0.1-1,000 nM caused weak venoconstriction as evidenced by small increase in Ppv. In anesthetized rats, when vasopressin was injected into the portal vein as a bolus consecutively at 0.01-100 nmol/kg, Psa increased dose-dependently with the peak increment of 60 ± 18 mmHg at 100 nmol/kg. Ppv and HBF decreased, with resultant increase in Rspl, indicating splanchnic vasoconstriction. In conclusion, hepatic venoconstrictor action of vasopressin was weak in rats. Vasopressin causes splanchnic vasoconstriction, resulting in a decrease in HBF and Ppv in anesthetized rats.

Esophageal Varices: Pathophysiology, Approach, and Clinical Dilemmas

Esophageal Varices: Pathophysiology, Approach, and Clinical Dilemmas

P87 Vascular Adhesion Protein-1 promotes increases in liver infiltrating CD4+ T cells and NKT cells and induction of fibrogenesis in steatohepatitis

IntroductionVascular Adhesion Protein-1 (VAP-1) is an adhesion molecule and membrane-bound amine oxidase. Our group has previously demonstrated that VAP-1 is able to support lymphocyte recruitment across human hepatic sinusoidal endothelium...

The transhepatic response to noradrenaline in the rabbit liver: the influence of arterioportal pressure gradient.

The dose-related responses of the hepatic arterial and portal venous vascular beds to bolus administration of noradrenaline (10(-10)-10(-4) mol), injected into the hepatic artery and portal vein, were studied in the isolated dual-perfused rabbit liver at both basal and raised tone. The transhepatic ratio, defined as the ratio between the intra-arterial molar ED50 dose and the intraportal dose required to give the same arterial response, was calculated for arterial and venous responses to noradrenaline. At basal tone, the transhepatic ratio for hepatic arterial vasoconstrictive responses was 500. Portal venous vasoconstrictive responses were similar in potency independent of injection site but differed significantly in analysis of dose-response slope and maximal response. At raised tone, the arterio-portal pressure gradient increased by 68.5 mmHg and there was a 10-fold increase in the transhepatic ratio for hepatic arterial responses, while the portal venous responses remained unchanged. These results demonstrate that arterio-portal pressure gradient has a powerful effect on transhepatic action of noradrenaline, and suggest a pre-sinusoidal site for the generation of both hepatic arterial and portal venous vascular resistance.

P46 Vascular adhesion protein-1 promotes inflammation and fibrogenesis in murine steatohepatitis

IntroductionVAP-1 is an adhesion molecule which promotes lymphocyte recruitment to the liver. It is released in a soluble form (sVAP-1) from adipose tissue and the hepatic vascular bed. sVAP-1 has...

New insights into the pathobiology of portal hypertension

Portal Hypertension is a frequent complication of cirrhosis and causes significant morbidity and mortality. Increased intrahepatic resistance is the primary factor but portal hypertension is also associated with changes in systemic and porto-sytemic collateral circulation. Cirrhosis is a state of vasoregulatory imbalance with excess vasoconstrictors and less vasodilators in hepatic circulation and the reverse is true for systemic circulation. Multiple pathophysiologic mechanisms including endothelial dysfunction, sinusoidal remodeling and angiogenesis are involved in increasing resistance in hepatic vascular bed. Current evidence suggests that these changes in vasoreactivity contribute to a significant proportion of intrahepatic vascular resistance and that they are reversible, providing an attractive target for therapeutic intervention.

The Clinical Value of Radioembolization in the Treatment of Inoperable Liver Cancer

Hepatocellular carcinoma (HCC) is a common malignancy worldwide. HCC-related mortality is high because most cases are diagnosed at an advanced stage. HCCs are relatively resistant to radiation and the liver is unable to tolerate the radiation doses required to achieve tumoricidal effects by standard external-beam radiation. Focal radiation techniques employing a 3D approach have been shown to safely permit higher levels of radiation to targeted regions within the liver. Delivery of therapy through hepatic artery branches preferentially affects HCC tumors and spares the surrounding liver parenchyma. Selective targeting of radionuclides to tumors has been shown to achieve high radiation dose ratios. Transarterial radionuclide therapies have been developed with the objective of achieving selective intra-arterial delivery of radiotherapy, including radioactive iodine-131 (131I), rhenium-188 (188Re), yttrium-90 (90Y) (resin or glass microspheres), and others. These treatments have been used to treat HCC via a selective transarterial approach as an alternative to TACE. Portal vein thrombosis (PVT) is a relative contraindication to transarterial chemoembolization (TACE); in contrast, high specific activity radiomicrospheres do not occlude a significant portion of the hepatic arterial vascular bed and can therefore be used in patients with PVT. The devices, toxicities, and results with use of the available radioembolic devices are reviewed in this article.

Vascular endothelial growth factor and angiopoietin-2 play a major role in the pathogenesis of vascular leakage in cirrhotic rats

Background and aims:The extent and molecular mechanisms governing plasma extravasation and formation of ascites in cirrhosis are unknown. Vascular endothelial growth factor-A (VEGF-A) and angiopoietin-2 (Ang-2) are endogenous substances with...

11C]palmitate kinetics across the splanchnic bed in arterial, portal and hepatic venous plasma during fasting and euglycemic hyperinsulinemia

The liver is fundamental in regulating lipid metabolism, and it supplies fatty acids (FA) to the rest of the body in the form of triglycerides (TG); the time-related relevance of this process is incompletely defined. The aim of the study was to investigate the appearance of labeled TG in the hepatic vascular bed after [11C]palmitate injection during fasting and insulin stimulation. Plasma [11C]palmitate kinetics in arterial, portal and hepatic venous lipid fractions was studied in eight anesthetized pigs during fasting or euglycemic hyperinsulinemia. Plasma analyses were conducted at 10 and 40 min after tracer injection. Corresponding liver positron emission tomography (PET) images were acquired for the semiquantitative determination of hepatic FA uptake. At 10 min, plasma levels of unchanged [11C]palmitate were lower in hyperinsulinemic than in fasting experiments in the artery and in the portal vein (P< or=.03), suggesting faster clearance. Levels of unmetabolized [11C]palmitate did not differ between portal and arterial plasma. In the fasting state, a tendency to a positive arterial and portal vs. hepatic venous gradient was observed, indicative of net hepatic [11C]palmitate extraction. Labeled TG were already detectable at 10 min (fasting vs. hyperinsulinemia, ns) and were higher in fasting than in hyperinsulinemic animals at 40 min (92+/-1% and 82+/-6% of arterial plasma radioactivity). Higher proportions of labeled TG were recovered in portal vein plasma, suggesting release by the gut. The portal and the arterial-portal vs. hepatic venous TG gradient tended to be positive. Accordingly, hepatic FA uptake was higher, but declined more rapidly during fasting than during hyperinsulinemia. The study indicates that the redistribution of [11C]palmitate between different lipid pools occurs within the short time interval of most PET experiments and is strongly influenced by insulin. Labeled TG constitute an additional [11C]palmitate source in the modeling of PET data.

Contribution of the portal flow on hepatic tissue perfusion increases in reduced hepatic vascular bed

Background: A hepatic artery–portal vein reciprocal response and hepatic hemodynamics have well been investigated under normal condition, but not under pathologic condition with decreased vascular bed. This study was designed to determine the hemodynamic changes in the hepatic blood flow, tissue perfusion and interrelationship between portal venous flow (PVF) and hepatic arterial flow (HAF) after inflow interruption in the various size of hepatic vascular bed. Methods: Anesthetized dogs were used to measure PVF and HAF using a transit time flow meter and hepatic tissue flow (HTF) using a laser Doppler flow meter before and after portal venous (PVO) or hepatic arterial occlusion (HAO) under various range of portal triad occlusion (PTO). Results: The ratio of HAF/TLF (total liver flow) was 38±14% under the basal condition. This ratio did not change under the 30% PTO where there was a similar decrease in PVF and HAF, but reduced to 25±12% under the 70% PTO where there was more selective reduction in HAF than PVF. Although a reciprocal HAF increase was observed under any conditions after PVO, the TLF and HTF decreases after PVO were largest under the 70% PTO with the highest PVF/TLF ratio. On the other hand, there was no reciprocal PVF increase in any conditions after HAO, and the TLF and HTF decreases after HAO were minimal under the 70% PTO with the lowest HAF/TLF ratio. Conclusions: With decreasing hepatic vascular bed, dependency of the remnant hepatic hemodynamics and tissue perfusion on the portal blood flow increased. These findings suggest that an integrity of portal venous flow becomes crucial in the remnant hepatic tissue perfusion after extensive hepatic resection.

Controlled Vasoregulation of Postischemic Liver Microcirculation - A Therapeutic Approach

One of the changes produced by ischemia and reperfusion is endothelin (ET)-mediated constriction of the hepatic vascular bed. This leads to microcirculatory disturbances and reduced blood flow, thereby causing local hypoxia and liver damage. Our aim was to induce stepwise changes of microvascular vessel diameters so as to define the best protective vessel width that could be produced by drug therapy and thereby to minimize ischemia/reperfusion injury. The mixed ET receptor antagonist bosentan was used in different dosages in a rat liver ischemia/reperfusion model with splenocaval shunt. In vivo microscopy was performed 30-90 min after reperfusion and local hepatic tissue pO2