endothelin-1 and Hypertension--Portal

Portal hypertension is pathologically defined as increase of portal venous pressure, mainly due to chronic liver diseases such as fibrosis and cirrhosis. In fibrotic liver, activated hepatic stellate cells increase their contraction in response to endothelin-1 (ET-1) via autocrine and paracrine stimulation from liver sinusoidal endothelial cells and injured hepatocytes. Clinical studies are limited with ET receptor antagonists in cirrhotic patients with portal hypertension. Hence, studies are needed to find molecules that block ET-1 synthesis. Accumulation of extracellular matrix proteins in the perisinusoidal space, tissue contraction, and alteration in blood flow are prominent during portal hypertension. Therefore, novel matrix modulators should be tested experimentally as well as in clinical studies. Specifically, tumor necrosis factor-α, transforming growth factor-β1, Wnt, Notch, rho-associated protein kinase 1 signaling antagonists, and peroxisome proliferator-activated receptor α and γ, interferon-γ and sirtuin 1 agonists should be tested elaborately against cirrhosis patients with portal hypertension.

Topics: Animals; Endothelin-1; Hepatic Stellate Cells; Humans; Hypertension, Portal; Models, Biological; Receptors, Endothelin; Signal Transduction

Acute or chronic insults to the liver are usually followed by a tissue repairing process. Unfortunately, this action, in most cases, is not effective enough to restore the normal hepatic structure and function. Instead, fibrogenesis and regenerative nodules formation ensue, which are relatively nonfunctioning. The common final stage of the process is liver cirrhosis with increased intrahepatic resistance to portal venous blood flow. Throughout the entire course, the extrahepatic circulatory dysfunction, including increased splanchnic blood flow, elevated portal venous blood flow and pressure, decreased splanchnic and peripheral vascular resistance, tachycardia, and increased cardiac output, are noted and denoted as portal hypertension with hyperdynamic circulatory dysfunction. When such a condition is established, patients may suffer from fatal complications such as gastroesophageal variceal hemorrhage, hepatic encephalopathy, or hepatorenal syndrome. The cause of such a circulatory dysfunction is not fully elucidated. Nevertheless, clarification of the pathophysiology definitely contributes to the control of portal hypertension-related complications. Herein, the molecular mechanism of this intriguing disaster is reviewed and discussed.

Topics: Animals; Endocannabinoids; Endothelin-1; Humans; Hypertension, Portal; Liver Cirrhosis; Neuropeptide Y; Portal Vein; Splanchnic Circulation; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A; Vascular Remodeling

Topics: Endothelin-1; Hemodynamics; Humans; Hypertension, Portal; Liver Circulation; Liver Cirrhosis; Receptors, Endothelin; Vascular Resistance

Portopulmonary hypertension (PPHT) is a rare but devastating complication in patients with portal hypertension, characterized by pulmonary arterial obliterative disease with a concomitant rise in pulmonary vascular resistance. A broad body of evidence has accumulated, indicating that endothelin (ET) peptides and their cognate receptors are causally involved in the pathophysiology of pulmonary arterial hypertension (PAH) owing to different aetiologies, including PPHT. In addition, the ET system may be involved in hepatic fibrotic remodelling and portal hypertension. Several experimental models have provided evidence that ET receptor antagonism may have therapeutic potential in PPHT. Initial experience has accumulated during the last 2 years, suggesting that targeting the ET system may have beneficial effects in the clinical setting. In these studies, the orally active, dual ET receptor antagonist bosentan improved pulmonary haemodynamics and functional capacity. These effects were sustained and occurred in the absence of adverse events. If these observations can be corroborated by controlled clinical trials, bosentan would offer several advantages over available therapies, which have major drawbacks owing to their invasive and demanding mode of application.

Topics: Administration, Oral; Antihypertensive Agents; Bosentan; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Humans; Hypertension, Portal; Hypertension, Pulmonary; Liver Cirrhosis; Liver Transplantation; Pulmonary Circulation; Sulfonamides; Treatment Outcome

Topics: Adult; Animals; Blood Pressure; Calcium Channels; Endothelin-1; Fibrosis; Hemorheology; Humans; Hypertension, Portal; Ion Channel Gating; Lipids; Liver; Liver Cirrhosis; Liver Cirrhosis, Experimental; Neovascularization, Pathologic; Nitric Oxide; Pericytes; Rats; Vasoconstrictor Agents; Vasodilator Agents

Hepatic stellate cells have received considerable attention as key components of the fibrogenic response to injury. Beyond this feature, they also have been implicated as regulators of sinusoidal vascular tone, and in disease states, in the pathogenesis of intrahepatic portal hypertension. The basis for this latter concept is derived from the following: (a) stellate cells are situated in a perisinusoidal orientation within the sinusoid, optimized for sinusoidal constriction; (b) a series of studies performed over the past decade have demonstrated that perisinusoidal stellate cells exhibit a remarkable capacity for cellular contraction, a characteristic that is most prominent after liver injury and stellate cell activation; and (c) in vivo microscopy studies have revealed that stellate cells can mediate sinusoidal constriction. Available evidence indicates that liver injury leads to a vascular disorder in which endothelin-1 is overproduced by stellate cells and endothelial cell-derived nitric oxide production is reduced. These abnormalities, in the context of exaggerated stellate cell contractility after liver injury, set up a paradigm in which stellate cells contribute to the increased intrahepatic resistance typical of portal hypertension. Furthermore, because stellate cell contractility and the mediators that control this function are dynamic processes, strategies that target exaggerated contractility provide an opportunity for novel therapeutics in intrahepatic portal hypertension.

Topics: Cell Physiological Phenomena; Endothelin-1; Humans; Hypertension, Portal; Liver; Nitric Oxide; Nitric Oxide Synthase; Regional Blood Flow

To assess the effect of tezosentan, a parenteral dual ET receptor antagonist, on splanchnic and systemic hemodynamics in patients with cirrhosis. In addition, the safety, pharmacokinetics, and pharmacodynamics of tezosentan were evaluated.. The population consisted of patients with cirrhosis with clinically significant portal hypertension. This was a randomized, double-blind, multicenter study. The patients were randomized 3:1 to tezosentan (3 mg/h for 2-3 h) or placebo. HVPG, hepatic blood flow (HBF, ICG method), and systemic arterial pressures were measured before and after tezosentan administration. Plasma concentrations of tezosentan and ET-1 were determined peripherally and in the hepatic vein.. Eighteen patients received tezosentan and six placebo. Baseline clinical, biochemical, and hemodynamic characteristics were balanced between the two groups. There was no significant treatment effect on HVPG. The extraction ratio (0.31), the plasma clearance of ICG (280 ml/min), and the HBF (1,430 ml/min) did not show any relevant changes during the infusion of tezosentan, and there were no differences between placebo- and tezosentan-treated patients. A linear relationship was observed between the maximum-fold increase in ET-1 concentration and the steady-state tezosentan plasma concentration (r = 0.82). There was a strong correlation (r = 0.88) between plasma clearance of ICG and that of tezosentan (10.2 l/h). Arterial pressure and heart rate did not significantly change in either group.. In patients with cirrhosis, a 2- to 3-h tezosentan infusion was safe and well tolerated but did not change the HVPG. Tezosentan infusion had no influence on the extraction ratio and plasma clearance of ICG and did not change HBF.

Topics: Antihypertensive Agents; Double-Blind Method; Endothelin Receptor Antagonists; Endothelin-1; Female; Heart Rate; Hemodynamics; Humans; Hypertension, Portal; Infusions, Parenteral; Liver; Liver Cirrhosis; Liver Cirrhosis, Alcoholic; Male; Metabolic Clearance Rate; Middle Aged; Pyridines; Severity of Illness Index; Splanchnic Circulation; Tetrazoles; Vasodilator Agents

In patients with cirrhosis, acute octreotide administration may transiently decrease the hepatic venous pressure gradient (HVPG). Information on long-term effects of octreotide is limited and controversial. We evaluated portal and systemic hemodynamics following a prolonged administration of long-acting octreotide in patients with cirrhosis.. Eighteen cirrhotic patients (alcoholic 12; age 55 yr [44-69]; Pugh's score 7.8; HVPG 17.3 mmHg [12-22]), no steatohepatitis on histology, were randomized to intramuscular octreotide 20 mg (group A) q 4 wk for 3 months or placebo (group B) in a double-blind fashion. At baseline and 3 months, we measured the HVPG, systemic hemodynamics, endothelin-1 (ET-1), and vascular endothelial growth factor (VEGF) in hepatic venous blood.. Patients remained compensated except for one episode of infection in each group. At 3 months, the HVPG decreased in group A but not in group B (16.5 +/- 1.3 to 11.8 +/- 1.5 mmHg, P < 0.01; 18.2 +/- 1 to 17 +/- 1.1 mmHg, P= 0.4). Systemic hemodynamics and liver function remained unchanged. In group A, but not in group B, VEGF decreased (21.2 +/- 4.7 to 13.7 +/- 3.5 pg/mL, P < 0.01; 22.5 +/- 7.8 to 19.2 +/- 5.4 pg/mL, P= 0.4). ET-1 remained stable. Changes in HVPG and VEGF were correlated (r = 0.49, P < 0.05).. Three months of long-acting octreotide in selected cirrhotic patients with portal hypertension decreases the HVPG independent of systemic hemodynamics and liver function. The decrease in VEGF blood levels suggests an improvement in splanchnic hyperemia.

Topics: Adult; Aged; Biomarkers; Biopsy; Delayed-Action Preparations; Double-Blind Method; Endothelin-1; Female; Follow-Up Studies; Gastrointestinal Agents; Humans; Hypertension, Portal; Immunoenzyme Techniques; Injections, Intramuscular; Liver Cirrhosis; Male; Middle Aged; Octreotide; Portal Pressure; Radioimmunoassay; Retrospective Studies; Time Factors; Treatment Outcome; Urotensins; Vascular Endothelial Growth Factor A

Increased endothelin (ET)-1 activity may contribute to the complications of cirrhosis and portal hypertension. The aim of this study was to assess the systemic and portal haemodynamic effects of selective ET-A and ET-B receptor antagonism in patients with cirrhosis.. Sixteen patients with cirrhosis and portal hypertension (aged 52 (1) years, Pugh score 6.2 (0.3)) underwent 24 studies with infusions of: (A) selective ET-A antagonist, BQ-123 (n = 8), at 1000 and 3000 nmol/min; (B) selective ET-B antagonist, BQ-788 (n = 8), at 100 and 300 nmol/min; or (C) matched saline placebo (n = 8) in a double blind randomised manner. Haemodynamic measurements were performed through pulmonary artery, hepatic venous, and femoral artery catheters.. Baseline patient characteristics were well matched. Compared with placebo, BQ-123 decreased mean arterial pressure (MAP -15 (11) mm Hg (-18%); p<0.02) and pulmonary vascular resistance index (PVRI -81 (54) dyn x s x m2/cm5 (-64%); p<0.05), with no effect on hepatic venous pressure gradient (HVPG), cardiac index (CI), or systemic vascular resistance index (SVRI). Compared with placebo, BQ-788 increased MAP (+11 (3) mm Hg (+12%); p<0.03) and SVRI (+1101 (709) dyn x s x m2/cm5 (+50%); p<0.05), reduced CI (-1.0 (0.4) l/min/m2 (-29%); p = 0.05) with no effect on HVPG or PVRI.. ET-1 contributes to maintenance of systemic and pulmonary haemodynamics without acutely affecting HVPG in patients with early cirrhosis. In this group of patients, the use of selective ET-A and ET-B antagonists for the management of variceal haemorrhage is likely to be limited.

Topics: Adult; Aged; Double-Blind Method; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Female; Hemodynamics; Humans; Hypertension, Portal; Liver Circulation; Liver Cirrhosis; Male; Middle Aged; Oligopeptides; Peptides, Cyclic; Piperidines; Pulmonary Circulation

The renal effects of octreotide, used for bleeding esophageal varices in cirrhosis, are controversial.. Fourteen cirrhotic patients (Child-Pugh; A/B/C: 1/12/1) were enrolled. Plasma nitrite and endothelin (ET) levels, urinary nitrite output, free water clearance (FWC) and fractional excretion of filtered sodium (FENa) were measured and renal Doppler ultrasound was carried out. Octreotide was infused at a rate of 0.75 microg/kg/h for 3 h after a bolus of 0.75 microg/kg body weight. All the parameters were reevaluated during octreotide administration while the patients acted as their own controls.. Octreotide induced significant reductions in urinary nitrite, FENa and FWC. Plasma ET levels increased (baseline: 6.7 pg/ml, octreotide: 8.4 pg/ml), whereas the plasma nitrite level did not change significantly after octreotide infusion. Overall, no significant change in renal resistive index (RRI) could be demonstrated on Doppler after octreotide administration. However, patients with elevated baseline RRI values had significantly more deterioration in FWC and FENa compared with patients with normal RRI in response to octreotide.. A marked decrease in FENa, FWC and urinary nitrite output, together with a significant increase in plasma ET level in response to octreotide, may indicate renal dysfunction in cirrhotic patients. This deleterious renal effect of octreotide may be more enhanced in patients with elevated baseline RRI.

Topics: Adult; Aged; Endothelin-1; Female; Gastrointestinal Agents; Gastrointestinal Hemorrhage; Humans; Hypertension, Portal; Kidney; Liver Cirrhosis; Male; Middle Aged; Nitrites; Octreotide; Salvage Therapy; Sodium; Ultrasonography, Doppler; Varicose Veins

To investigate variations of plasma endothelin (ET) and its clinical significance in portal hypertensive patients with esophageal variceal hemorrhage.. Sixty-six patients with portal hypertension were randomly divided into 2 groups. Group I (32 patients) received general therapy and Group II (34 patients) received general therapy and UTI after hemorrhage. The plasma ET concentration and liver function were determined at 1, 2, 4, 7, 10, and 14 d after the hemorrhage. Another 20 patients without the hemorrhage were elected as the control group.. At 7 and 14 d after the hemorrhage, the levels of TBIL, ALT and AST were elevated at first and then decreased in Groups I and II. The decrease of TBIL, ALT and AST levels was significantly faster in Group II than in Group I (P < 0.05, P < 0.01, P < 0.05, respectively) on 14 d after the hemorrhage. At 1 d after the hemorrhage the ET concentration was markedly increased in Group I and II as compared with the control group (P < 0.01). Then it was gradually decreased on 10 d after the hemorrhage. The ET concentration in Group II was decreased more rapidly than that in Group I on 2, 4 and 7 d after the hemorrhage (P < 0.05; P < 0.01; P < 0.05, respectively). The ET concentration was positively correlated to TBIL levels in groups I and II (r = 0.734, P < 0.01). And the decreased index of ET concentration was negatively correlated to the increased index of TBIL (r = -0.486, P < 0.05).. The increased plasma ET in portal hypertensive patients with hemorrhage may contribute to liver injury. UTI can protect the liver function by inhibiting ALT, AST, TBIL and ET level.

Topics: Adult; Aged; Endothelin-1; Esophageal and Gastric Varices; Female; Glycoproteins; Humans; Hypertension, Portal; Liver Failure; Male; Middle Aged; Trypsin Inhibitors

Liver cirrhosis is associated with increased intrahepatic resistance due to hepatic fibrosis and exaggerated vasoconstriction. Recent studies have indicated that proton pump inhibitors (PPIs), in addition to acid suppression, modulate vasoactive substances and vasoresponsiveness. PPIs are frequently prescribed in patients with cirrhosis due to a higher prevalence of peptic ulcers, however other impacts are unknown.. Esomeprazole did not affect hepatic ET-1 vasoresponsiveness. The hepatic protein expressions of the aforementioned factors were not significantly different among the groups. There were no significant differences in hemodynamics, liver biochemistry and hepatic fibrosis after chronic esomeprazole administration.. PPIs did not affect hepatic vasoresponsiveness or the release of vasoactive substances. Furthermore, they did not influence hemodynamics, liver biochemistry or severity of hepatic fibrosis in the cirrhotic rats.

Topics: Animals; Endothelin-1; Esomeprazole; Hemodynamics; Hypertension, Portal; Liver Cirrhosis, Experimental; Male; Proton Pump Inhibitors; Rats; Rats, Sprague-Dawley

Cirrhosis is characterized by increased intrahepatic vascular resistance and enhanced vasocontractile responsiveness that impedes portal inflow and elevates portal pressure, in which endothelin-1 (ET-1) plays a role. Diabetes and glucose influence vasoresponsiveness but their impact on the intrahepatic vascular bed in cirrhosis is unknown. To investigate intrahepatic ET-1 vasoresponsiveness in cirrhotic rats with and without diabetes and to explore the underlying mechanisms.. Spraque-Dawley rats received common bile-duct ligation (BDL) to induce cirrhosis. Streptozotocin was injected to induce diabetes in the BDL rats (BDL/STZ). In situ liver perfusion was performed to obtain the ET-1 concentration-response curves. The basic hemodynamics and hepatic protein expressions of ET-1 receptors, pERK, ERK, pAkt, Akt, iNOS, eNOS, peNOS and calmodulin were evaluated. The circulating concentrations of N-terminal pro-brain natriuretic peptide (NT-ProBNP), blood urea nitrogen (BUN) and creatinine were also determined.. Body weight, mean arterial pressure, heart rate and survival rate were significantly decreased in the BDL/STZ rats. The perfusion pressure changes in response to ET-1 were higher in the BDL/STZ group for all perfusates. ETA receptor and pERK expressions were enhanced in the BDL/STZ group. The circulating concentrations of NT-ProBNP, BUN and creatinine, as well as SMA flow, were not significantly different between the BDL and BDL/STZ groups.. Cirrhotic rats with diabetes showed higher intrahepatic ET-1 vasoresponsiveness than normoglycemic cirrhotic rats. This effect is not affected by changes in perfused glucose concentration and may be related, at least in part, to intrahepatic ETA R receptor and pERK over-expression.

Topics: Animals; Blood Urea Nitrogen; Creatinine; Diabetes Mellitus, Experimental; Disease Models, Animal; eIF-2 Kinase; Endothelin-1; Hemodynamics; Hypertension, Portal; Liver Cirrhosis, Experimental; Male; Natriuretic Peptide, Brain; Peptide Fragments; Perfusion; Portal Pressure; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Up-Regulation; Vasoconstriction

Hypo-perfusion resulting from intense renal vasoconstriction is traditionally contributed to renal dysfunction in advanced liver disease, although cumulative studies demonstrated renal vasodilatation with impaired vascular contractility to endogenous vasoconstrictors in portal hypertension and compensated liver cirrhosis. The pathophysiology of altered renal hemodynamics remains unclear. This study, using a rat model of portal hypertension with superimposed endotoxemia, was designed to delineate the evolution of renal vascular reactivity and vaso-regulatory gene expression during liver disease progression.. Rats were randomized into sham surgery (SHAM) or partial portal vein ligation (PVL). Endotoxemia was induced by intraperitoneal injection of lipopolysaccharide (LPS) on the seventh day following surgery. Isolated kidney perfusion was performed at 0.5 h or 5 h after LPS to evaluate renal vascular response to endothelin-1.. In contrast to impaired vascular contractility of SHAM rats, PVL rats displayed enhanced renal vascular reactivity to endothelin-1 at 5 h following endotoxemia. There were extensive upregulations of inducible nitric oxide synthase in kidney tissues of endotoxemic rats. The changes of renal endothelin receptor type A (ETA ) level paralleled with the changes of renal vascular reactivity in LPS-treated rats. Compared with SHAM rats, PVL rats showed increased renal ETA and phosphorylated extracellular-signal-regulated kinases 1/2 (p-ERK1/2) at 5 h after LPS.. LPS-induced systemic hypotension induces a paradoxical change of renal vascular response to endothelin-1 between SHAM and PVL rats. LPS-induced renal vascular hyperreactivity in PVL rats was associated with upregulation of renal ETA and subsequent activation of ERK1/2 signaling.

Topics: Animals; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Hypertension, Portal; Kidney; Lipopolysaccharides; Male; MAP Kinase Signaling System; Rats, Sprague-Dawley; Receptor, Endothelin A; Up-Regulation; Vasoconstriction

To investigate endothelin-1 hypo-responsive associated with portal hypertension in order to improve patient treatment outcomes.. Wild type, eNOS(-/-) and iNOS(-/-) mice received partial portal vein ligation surgery to induce portal hypertension or sham surgery. Development of portal hypertension was determined by measuring the splenic pulp pressure, abdominal aortic flow and portal systemic shunting. To measure splenic pulp pressure, a microtip pressure transducer was inserted into the spleen pulp. Abdominal aortic flow was measured by placing an ultrasonic Doppler flow probe around the abdominal aorta between the diaphragm and celiac artery. Portal systemic shunting was calculated by injection of fluorescent microspheres in to the splenic vein and determining the percentage accumulation of spheres in liver and pulmonary beds. Endothelin-1 hypo-response was evaluated by measuring the change in abdominal aortic flow in response to endothelin-1 intravenous administration. In addition, thoracic aorta endothelin-1 contraction was measured in 5 mm isolated thoracic aorta rings ex-vivo using an ADI small vessel myograph.. In wild type and iNOS(-/-) mice splenic pulp pressure increased from 7.5 ± 1.1 mmHg and 7.2 ± 1 mmHg to 25.4 ± 3.1 mmHg and 22 ± 4 mmHg respectively. In eNOS(-/-) mice splenic pulp pressure was increased after 1 d (P = NS), after which it decreased and by 7 d was not significantly elevated when compared to 7 d sham operated controls (6.9 ± 0.6 mmHg and 7.3 ± 0.8 mmHg respectively, P = 0.3). Abdominal aortic flow was increased by 80% and 73% in 7 d portal vein ligated wild type and iNOS when compared to shams, whereas there was no significant difference in 7 d portal vein ligated eNOS(-/-) mice when compared to shams. Endothelin-1 induced a rapid reduction in abdominal aortic blood flow in wild type, eNOS(-/-) and iNOS(-/-) sham mice (50% ± 8%, 73% ± 9% and 47% ± 9% respectively). Following portal vein ligation endothelin-1 reduction in blood flow was significantly diminished in each mouse group. Abdominal aortic flow was reduced by 19% ± 9%, 32% ± 10% and 9% ± 9% in wild type, eNOS(-/-) and iNOS(-/-) mice respectively.. Aberrant endothelin-1 response in murine portal hypertension is NOS isoform independent. Moreover, portal hypertension in the portal vein ligation model is independent of ET-1 function.

Topics: Animals; Aorta, Abdominal; Aorta, Thoracic; Blood Flow Velocity; Disease Models, Animal; Endothelin-1; Hypertension, Portal; Injections, Intravenous; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Portal Pressure; Regional Blood Flow; Time Factors; Vasoconstriction; Vasoconstrictor Agents

The invasive measurement of hepatic venous pressure gradient is the recommended method for the assessment of portal hypertension. We assessed if the mediators that regulate portal hypertension may be used as noninvasive markers of portal hypertension and liver insufficiency.. We explored in prospective, observational study the concentration of endothelin-1, nitric oxide, and transforming growth factor-β1/2 in peripheral and hepatic venous blood; their relationship with the values of portal hypertension and liver insufficiency; and their level changes 4-6 months after non-selective beta-blocker therapy in cirrhotic patients with non-bleeding esophageal varices.. (1) Cirrhotics have significantly increased peripheral endothelin 1 and decreased transforming growth factor-β1 levels; (2) peripheral levels of all factors correlated significantly with their hepatic levels; (3) after therapy, peripheral endothelin-1 levels significantly increased, but transforming growth factor-β2 levels decreased and were lower in patients with pressure gradient value normalization; (4) before and after therapy, peripheral and hepatic endothelin-1, transforming growth factor-β1/2 levels correlated significantly with liver failure indicators (laboratory parameters, Child-Pough and MELD scores) and pressure gradient values.. Peripheral endothelin-1 and transforming growth factor-β1 levels, which strongly correlate with their hepatic levels, reflect the stage of portal hypertension and liver insufficiency in cirrhosis.

Topics: Adrenergic beta-Antagonists; Adult; Aged; Biomarkers; Endothelin-1; Female; Humans; Hypertension, Portal; Liver; Liver Cirrhosis; Liver Function Tests; Male; Middle Aged; Nitric Oxide; Portal Pressure; Prospective Studies; Transforming Growth Factor beta; Transforming Growth Factor beta1

GPBAR1 is a bile acids activated receptor expressed in entero-hepatic tissues. In the liver expression of GPBAR1 is restricted to sinusoidal and Kuppfer cells. In the systemic circulation vasodilation caused by GPBAR1 agonists is abrogated by inhibition of cystathione-γ-liase (CSE), an enzyme essential to the generation of hydrogen sulfide (H2S), a vasodilatory agent. Portal BAR501 is a semisynthetic bile acid derivative endowed with a potent and selective agonistic activity toward GPBAR1.. Cirrhosis was induced in mice by carbon tetrachloride (CCL4) administration for 9 weeks. Liver endothelial dysfunction was induced by feeding wild type and Gpbar1-/- mice with methionine for 4 weeks. In both models, mice were administered BAR501, 15 mg/kg/day.. By transactivation assay we demonstrate that BAR501 is a selective GPBAR1 agonist devoid of any FXR agonistic activity. In naïve rats, BAR501 effectively reduced hepatic perfusion pressure and counteracted the vasoconstriction activity of norepinephrine. In the CCl4 model, 9 weeks treatment with BAR501 effectively protected against development of endothelial dysfunction by increasing liver CSE expression and activity and by reducing endothelin (ET)-1 gene expression. In mice feed methionine, treatment with BAR501 attenuated endothelial dysfunction and caused a GPBAR1-dependent regulation of CSE. Using human liver sinusoidal cells, we found that modulation of CSE expression/activity is mediated by both genomic (recruitment of CREB to CRE in the CSE promoter) and non-genomic effects, involving a Akt-dependent phosporylation of CSE and endothelial nitric oxide (NO) synthase (eNOS). BAR501, phosphorylates FOXO1 and inhibits ET-1 transcription in liver sinusoidal cells.. BAR501, a UDCA-like GPBAR1 agonist, rescues from endothelial dysfunction in rodent models of portal hypertension by exerting genomic and non-genomic effects on CSE, eNOS and ET-1 in liver sinusoidal cells.

Topics: Animals; Bile Acids and Salts; Cholestanols; Endothelin-1; Endothelium, Vascular; Forkhead Box Protein O1; Forkhead Transcription Factors; Humans; Hydrogen Sulfide; Hypertension, Portal; Liver; Male; Mice; Mice, Inbred C57BL; Oncogene Protein v-akt; Rats; Rats, Wistar; Real-Time Polymerase Chain Reaction; Receptors, G-Protein-Coupled; Signal Transduction; Ursodeoxycholic Acid

Splenectomy is an effective technique in living donor liver transplantation (LDLT) with small-for-size (SFS) liver grafts for overcoming SFS liver graft injury. However, the protective mechanism of splenectomy is still unclear. The aim of this study was to investigate how splenectomy could attenuate SFS graft injury through the measurement of biochemical factors, particularly the expression of endothelin (ET)-1, which is a key molecule of microcirculatory disorders by mediating sinusoidal vasoconstriction. We performed rat orthotopic liver transplantation using SFS liver grafts with or without splenectomy. We investigated intragraft expression of ET-1 mRNA and hepatic protein levels of ET-1. In addition, portal pressure, hepatic injury and morphological changes, and survival rate were evaluated. In result, intragraft ET-1 mRNA expression after SFS liver transplantation was significantly downregulated by splenectomy, and hepatic expression of ET-1 in SFS grafts was rarely observed. Splenectomy inhibited the increase in portal pressure, ameliorated SFS liver graft injury and improved the graft survival rate after SFS liver transplantation. In conclusion, splenectomy improved the SFS liver injury and decreased the expression of ET-1 by attenuating portal hypertension on SFS liver transplantation. Downregulation of intragraft ET-1 expression plays important roles in the protective mechanism of splenectomy in SFS liver transplantation.

Topics: Animals; Down-Regulation; Endothelin-1; Graft Survival; Hypertension, Portal; Liver; Liver Failure; Liver Transplantation; Living Donors; Male; Rats; Rats, Inbred Lew; RNA, Messenger; Splenectomy

The effect of splenomegaly in patients with liver cirrhosis and portal hypertension is not fully understood. This study was designed to determine the effect of laparoscopic splenectomy on portal haemodynamics in these patients.. Patients with liver cirrhosis and portal hypertension who underwent laparoscopic splenectomy in Kyushu University Hospital from January 2006 to March 2009 were evaluated retrospectively. Correlations between splenic size and portal haemodynamics, and changes in portal haemodynamics and in levels of the vasoactive agents endothelin (ET) 1 and nitric oxide metabolites (NOx) before and 7-10 days after laparoscopic splenectomy were analysed.. Portal venous (PV) blood flow, PV cross-sectional area and PV congestion index correlated significantly with splenic size (P < 0·050). All three were significantly reduced following splenectomy in 59 patients. The hepatic venous pressure gradient, measured in 18 patients, decreased by 25 per cent after splenectomy (P < 0·001). Portal vascular resistance was also reduced, by 21 per cent (P = 0·009). The peripheral blood concentration of ET-1 decreased from 2·95 to 2·11 pg/ml (P < 0·001), and that of NOx tended to decrease (from 29·2 to 25·0 pg/ml; P = 0·068). In hepatic venous blood, the level of ET-1 decreased from 2·37 to 1·83 pg/ml (P = 0·006), whereas NOx concentration tended to increase (from 24·5 to 30·9 pg/ml; P = 0·067).. In patients with liver cirrhosis and portal hypertension, splenectomy reduced portal venous pressure. A decrease in splanchnic blood flow, by eliminating splenic blood flow, and reduction in intrahepatic vascular resistance, by normalizing hepatic concentrations of ET-1 and NOx, may both have contributed.

Topics: Ascites; Blood Cell Count; Blood Flow Velocity; Endothelin-1; Esophageal and Gastric Varices; Hemodynamics; Humans; Hypertension, Portal; Laparoscopy; Liver Cirrhosis; Male; Middle Aged; Nitric Oxide; Organ Size; Prothrombin Time; Retrospective Studies; Splanchnic Circulation; Spleen; Splenectomy; Treatment Outcome

To investigate the effects of Glytan on splanchnic hemodynamics and its reduction of portal pressure in portal hypertensive rats.. Glytan (Ganluotong in Chinese), is composed of salvianolic acid B and diammonium glycyrrhizinate. Portal hypertension (PHT) was induced in the rats by common bile duct ligation (BDL). Hemodynamic studies were performed using the colored microsphere method. Radioimmunoassay (RIA) was used to determine endothelin (ET)-1 levels in the mesenteric circulation. Western blotting methods were used to investigate the effect of Glytan on ET A receptor (ETAR), ET B receptor (ETBR), endothelial NO synthase (eNOS), G-protein-coupled receptor kinase (GRK)2, and β-arrestin 2 expression in the mesentery. The mRNA of ETAR and ETBR was determined using real-time polymerase chain reaction.. Treatment with Glytan reduced portal pressure (PP) and portal territory blood flow (PTBF) and increased both mean arterial pressure (MAP) and splanchnic vascular resistance (SVR). Especially at 4 wk, PP decreased by about 40%, while MAP increased by 13%, SVR increased by 12%, and PTBF decreased by about 21%. The effect of blood flow reduction was greatest in the mesentery (about 33%) at 4 wk. The mesenteric circulation ET-1 levels of BDL rats were lower and negatively correlated with PP at 4 wk. Glytan can increase mesenteric ET-1 content and inhibit ETBR, eNOS, GRK2, and β-arrestin 2 expression in the mesentery. Moreover, Glytan showed no effect on the expression of ETAR protein and mRNA.. The decreased PP and PTBF observed after Glytan treatment were related to increased mesenteric vasoconstriction and increased receptor sensitivity to vasoconstrictor.

Topics: Animals; Benzofurans; Blood Flow Velocity; Disease Models, Animal; Drugs, Chinese Herbal; Endothelin B Receptor Antagonists; Endothelin-1; G-Protein-Coupled Receptor Kinase 2; Glycyrrhetinic Acid; Hypertension, Portal; Male; Mesentery; Nitric Oxide Synthase Type III; Portal Pressure; Protein Kinase Inhibitors; Rats, Sprague-Dawley; Receptor, Endothelin B; Signal Transduction; Splanchnic Circulation; Time Factors; Vasoconstriction; Vasoconstrictor Agents

To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling.. PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP) was measured directly via catheters placed in the portal vein tract. The level of endothelin-1 (ET-1) in the mesenteric circulation was determined by radioimmunoassay, and the expression of the endothelin A receptor (ETAR) and endothelin B receptor (ETBR) was assessed by immunofluorescence and Western blot. Additionally, expression of G protein coupled kinase-2 (GRK2) and β-arrestin 2, which influence endothelin receptor sensitivity, were also studied by Western blot.. PP of CBDL rats increased significantly (11.89 ± 1.38 mmHg vs 16.34 ± 1.63 mmHg). ET-1 expression decreased in the mesenteric circulation 2 and 4 wk after CBDL. ET-1 levels in the systemic circulation of CBDL rats were increased at 2 wk and decreased at 4 wk. There was no change in ETAR expression in response to CBDL; however, increased expression of ETBR in the endothelial cells of mesenteric arterioles and capillaries was observed. In sham-operated rats, ETBR was mainly expressed in the CD31⁺ endothelial cells of the arterioles. With development of PHT, in addition to the endothelial cells, ETBR expression was noticeably detectable in the SMA⁺ smooth muscle cells of arterioles and in the CD31⁺ capillaries. Following CBDL, increased expression of GRK2 was also found in mesenteric tissue, though there was no change in the level of β-arrestin 2.. Decreased levels of ET-1 and increased ETBR expression in the mesenteric circulation following CBDL in rats may underlie mesenteric vasodilation in individuals with PHT. Mechanistically, increased GRK2 expression may lead to desensitization of ETAR, as well as other vasoconstrictors, promoting this vasodilatory effect.

Topics: Animals; Arrestins; Arterioles; beta-Arrestin 2; beta-Arrestins; Blotting, Western; Capillaries; Disease Models, Animal; Endothelin-1; G-Protein-Coupled Receptor Kinase 2; Hypertension, Portal; Male; Microscopy, Fluorescence; Platelet Endothelial Cell Adhesion Molecule-1; Pressure; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B

Endothelin-1 (ET-1) exerts vasoconstrictive effect on portal-systemic collateral vascular bed of portal hypertensive rats. Statins are lipid-lowering agents with nitric oxide (NO)-related vasodilatory effects. Considering NO-associated vascular hyporesponsiveness to vasoconstrictors and shunting formation in portal hypertension, this study investigated the effects of simvastatin on 1) the portal-systemic collateral vascular responsiveness to ET-1 and 2) the portal-systemic shunting degree.. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Simvastatin (20 mg/kg/day) or distilled water (control) was randomly administered by oral gavage since 2 days prior to until 7 days after PVL. Systemic and portal hemodynamics were measured on the 8th day. In another series, collateral perfusion with Krebs solution at different flow rates was performed to get flow-pressure curves which serve as an index of shunting degree. To survey the direct vascular effect, PVL rats randomly underwent preincubation with 1) Krebs solution, that is, the control group; or Krebs solution plus 2) simvastatin; 3) simvastatin + N (ω)-nitro-L-arginine (NNA, a NO synthase inhibitor); 4) simvastatin + indomethacin (a cyclooxygenase inhibitor), followed by ET-1 to evaluate the collateral vascular responsiveness.. Chronic simvastatin treatment significantly reduced portal pressure. The flow-pressure curves were similar between two groups. Simvastatin preincubation reduced collateral perfusion pressure changes to ET-1 (p < 0.05), which were partially reversed by NNA (p < 0.05), but not by indomethacin. Conclusions. Chronic simvastatin treatment significantly improved portal hypertension. The effect was at least partially exerted by decreased portal-systemic collateral vascular resistance through NO-mediated vascular hyporesponsiveness. The severity of portal-systemic collaterals was not influenced by simvastatin.

Topics: Animals; Collateral Circulation; Cyclooxygenase Inhibitors; Endothelin-1; Hemodynamics; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension, Portal; Indomethacin; Linear Models; Male; Nitric Oxide Synthase; Random Allocation; Rats; Rats, Sprague-Dawley; Simvastatin; Treatment Outcome; Vascular Resistance; Vasoconstriction; Vasoconstrictor Agents

In cirrhosis, sinusoidal endothelial cell injury results in increased endothelin-1 (ET-1) and decreased nitric oxide synthase (NOS) activity, leading to portal hypertension. However, the effects of transplanted endothelial progenitor cells (EPCs) on the cirrhotic liver have not yet been clarified. We investigated whether EPC transplantation reduces portal hypertension.. Cirrhotic rats were created by the administration of carbon tetrachloride (CCl(4) ) twice weekly for 10 weeks. From week 7, rat bone marrow-derived EPCs were injected via the tail vein in this model once a week for 4 weeks. Endothelial NOS (eNOS), vascular endothelial growth factor (VEGF) and caveolin expressions were examined by Western blots. Hepatic tissue ET-1 was measured by a radioimmunoassay (RIA). Portal venous pressure, mean aortic pressure, and hepatic blood flow were measured.. Endothelial progenitor cell transplantation reduced liver fibrosis, α-smooth muscle actin-positive cells, caveolin expression, ET-1 concentration and portal venous pressure. EPC transplantation increased hepatic blood flow, protein levels of eNOS and VEGF. Immunohistochemical analyses of eNOS and isolectin B4 demonstrated that the livers of EPC-transplanted animals had markedly increased vascular density, suggesting reconstitution of sinusoidal blood vessels with endothelium.. Transplantation of EPCs ameliorates vascular dysfunction and portal hypertension, suggesting this treatment may provide a new approach in the therapy of portal hypertension with liver cirrhosis.

Topics: Animals; Blood Vessels; Carbon Tetrachloride; Caveolins; Cell Proliferation; Endothelial Cells; Endothelin-1; Endothelium; Hypertension, Portal; Liver Circulation; Liver Cirrhosis, Experimental; Male; Nitric Oxide Synthase Type III; Portal Pressure; Rats; Rats, Wistar; Stem Cell Transplantation; Vascular Endothelial Growth Factor A

Circulatory dysfunction in portal hypertension is characterized by increased cardiac output, decreased systemic vascular resistance, a fall in mean arterial pressure secondary to splanchnic and systemic vasodilation and hence renal hypoperfusion. Previous studies have disclosed that renal vasculatures of portal hypertensive rats had lower perfusion pressure and hyporesponsiveness to endogenous vasoconstrictors. However, the sequences of altered renal haemodynamics have never been described. This study aimed to explore the evolution of renal vascular hyporeactivity and associated mechanisms during portal hypertension.. All rats were randomized into partial portal vein ligation (PVL) or shamed surgery. Isolated kidney perfusion was performed at postoperative day 1, 4, 7 and 14, respectively, to evaluate chronologically renal vascular response to endothelin-1. Renal arteries and kidneys were harvested for further analysis.. Impaired renal vascular reactivity to endothelin-1 developed 1 week following PVL. There were extensive up-regulations of vasodilative nitric oxide synthase (NOS) and cyclooxygenase-2 in renal arteries of PVL rats. Among them, the changes in endothelial NOS paralleled with the evolution of renal vascular hyporesponsiveness. Preincubation of NOS inhibitor attenuated the renal vascular hyporeactivity in PVL rats. Up-regulated NOS and down-regulated cyclooxygenase-2 in kidneys of PVL rats might play a critical role to maintain renal circulation and body fluid homoeostasis in response to systemic hypotension.. This investigation highlights the versatile nature of renal vasculatures in portal hypertension, which is replete with compensatory mechanisms. It may help to unveil potential mechanisms of severe renal dysfunction in advanced liver disease.

Topics: Animals; Arterial Pressure; Cyclooxygenase 2; Endothelin-1; Heart Rate; Hypertension, Portal; Kidney; Ligation; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Portal Pressure; Portal Vein; Random Allocation; Rats; Rats, Sprague-Dawley; Renal Artery; RNA, Messenger; Time Factors; Up-Regulation; Vasoconstrictor Agents; Vasodilation

Leptin, the ob gene product, is a protein released from adipocytes and has been detected in fibrotic and cirrhotic livers. Leptin in brain has an inhibitory effect on food intake. Nonalcoholic steatohepatitis (NASH) is characterized by hyperleptinemia. This study explores the possible mechanisms of hyperleptinemia in relation to increased intrahepatic resistance (IHR) and portal hypertension in NASH cirrhotic rats. NASH cirrhotic rats with hyperleptinemia were induced in Zucker (fa/fa) and lean rats by feeding the animals a high fat/methionine-choline-deficient (HF/MCD) diet with and without exogenous administration of recombinant leptin. Portal venous pressure (PVP), IHR, plasma and hepatic levels of various substances, histopathology of the liver, the hepatic hydroxyproline content, and the expression of various hepatic protein and messenger RNA (mRNA) were measured. Hepatic microcirculatory dysfunction and the vasoconstrictive response to endothelin-1 were also observed using a liver perfusion system and intravital microscopy. Finally, the effect of leptin on hepatic stellate cells (HSCs) was evaluated. Both in HF/MCD-Zucker and HF/MCD+leptin lean rats, significant hepatic fibrogenesis and cirrhosis, marked portal hypertension, microcirculatory dysfunction, an enhanced vasoconstrictive response to endothelin-1, and an increased IHR were found to be associated with higher levels of hepatic endothelin-1 and endocannabinoids, expression levels of the cannabinoid type 1 receptor, endothelin-1 type A receptor (ET(A) R), activator protein-1, transforming growth factor beta (TGF-β)(1), osteopontin, tumor necrosis factor alpha (TNF-α), leptin, and the leptin receptor (OBRb). Interestingly, acute incubation of leptin directly increases the expression of ET(A) R, OBRb and activator protein-1 in HSCs.. An HF/MCD diet and hyperleptinemia increase hepatic endocannabinoids production, promote hepatic fibrogenesis, enhance the hepatic vasoconstrictive response to endothelin-1, and aggravate hepatic microcirculatory dysfunction; these events subsequently increase IHR and portal hypertension in NASH cirrhotic rats.

Topics: Animals; Biopsy, Needle; Body Weight; Cannabinoid Receptor Modulators; Diet, High-Fat; Disease Models, Animal; Disease Progression; Endocannabinoids; Endothelin-1; Fatty Liver; Hepatic Stellate Cells; Hypertension, Portal; Immunohistochemistry; Insulin Resistance; Kupffer Cells; Leptin; Liver; Microcirculation; Non-alcoholic Fatty Liver Disease; Random Allocation; Rats; Rats, Zucker; RNA, Messenger; Statistics, Nonparametric

Endothelial cell nitric-oxide (NO) synthase (eNOS), the enzyme responsible for synthesis of NO in the vasculature, undergoes extensive post-translational modifications that modulate its activity. Here we have identified a novel eNOS interactor, G-protein-coupled receptor (GPCR) kinase interactor-1 (GIT1), which plays an unexpected role in GPCR stimulated NO signaling. GIT1 interacted with eNOS in the endothelial cell cytoplasm, and this robust association was associated with stimulatory eNOS phosphorylation (Ser(1177)), enzyme activation, and NO synthesis. GIT1 knockdown had the opposite effect. Additionally, GIT1 expression was reduced in sinusoidal endothelial cells after liver injury, consistent with previously described endothelial dysfunction in this disease. Re-expression of GIT1 after liver injury rescued the endothelial phenotype. These data emphasize the role of GPCR signaling partners in eNOS function and have fundamental implications for vascular disorders involving dysregulated eNOS.

Topics: Animals; Cell Cycle Proteins; Cells, Cultured; Down-Regulation; Endothelial Cells; Endothelin-1; Gene Expression; Hepatic Veins; Homeostasis; Hypertension, Portal; Liver; Male; Nitric Oxide; Nitric Oxide Synthase Type III; Phosphoproteins; Protein Binding; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B; Signal Transduction

Non-alcoholic fatty liver disease can progress to steatohepatitis and fibrosis, and is also associated with impaired liver regeneration. The pathophysiology remains elusive. We recently showed that severe steatosis is associated with an increase in portal pressure, suggesting liver flow impairment. The objective of this study is to directly assess total intrahepatic resistance and its potential functional and structural determinants in an in situ perfusion model. Male Wistar rats fed a control (n = 30) or a methionine-choline-deficient (MCD) diet (n = 30) for 4 weeks were compared. Liver tissue and serum analysis, in vivo haemodynamic measurements, in situ perfusion experiments and vascular corrosion casts were performed. The MCD group showed severe steatosis without inflammation or fibrosis on histology. Serum levels and liver tissue gene expression of interleukin (IL)-6, tumour necrosis factor-α, IL-1β and interferon-γ, liver tissue myeloperoxidase activity and liver immunohistochemistry with anti-CD68 and anti-α smooth muscle actin were comparable between groups, excluding significant inflammation. Flow-pressure curves were significantly different between groups for all flows (slope values: 0.1636 ± 0.0605 mm Hg/ml/min in controls vs 0.7270 ± 0.0408 mm Hg/ml/min in MCD-fed rats, P < 0.001), indicating an increased intrahepatic resistance, which was haemodynamically significant (portocaval pressure gradient 2.2 ± 1.1 vs 8.2 ± 1.3 mm Hg in controls vs MCD, P<0.001). Dose-response curves to acetylcholine were significantly reduced in MCD-fed rats (P < 0.001) as was the responsiveness to methoxamine (P<0.001). Vascular corrosion casts showed a replacement of the regular sinusoidal anatomy by a disorganized pattern with multiple interconnections and vascular extensions. Liver phosphorylated endothelial NO synthase (eNOS)/eNOS and serum nitrite/nitrate were not increased in severe steatosis, whereas liver thromboxane synthase expression, liver endothelin-1 (ET-1) expression and serum andothelin-1 concentration were significantly increased. Severe steatosis induces a haemodynamically significant increase in intrahepatic resistance, which precedes inflammation and fibrogenesis. Both functional (endothelial dysfunction and increased thromboxane and ET-1 synthesis) and structural factors are involved. This phenomenon might significantly contribute to steatosis-related disease.

Topics: Analysis of Variance; Animals; Cytokines; Endothelin-1; Endothelium, Vascular; Fatty Liver; Hypertension, Portal; Liver; Liver Circulation; Liver Cirrhosis; Male; Methoxamine; Microscopy, Electron, Scanning; Microvessels; Nitric Oxide; Nitric Oxide Synthase Type III; Rats; Rats, Wistar; Thromboxane-A Synthase; Vasoconstriction; Vasoconstrictor Agents

The effect of an endothelin (ET) A receptor antagonist on hepatic hemodynamics in cirrhotic rats was examined.. Portal pressure and hepatic tissue blood flow in cirrhotic rats were measured. Plasma ET-1 levels were determined by radioimmunoassay. BQ-123 was infused to these rats at a rate of 10 nmol/min. The sinusoids were observed by scanning electron microscopy. The localization of ET-1 and ETA receptors was examined using the indirect immunoperoxidase method.. In cirrhotic rats, the portal pressure significantly increased to 16.6 ± 1.5 cm H2O, and the hepatic tissue blood flow markedly decreased. Plasma ET-1 levels in cirrhotic rats were higher than those in normal rats. When BQ-123 was infused, the portal pressure was significantly reduced by more than 2 cm H2O, compared with the control group (p < 0.05). Hepatic tissue blood flow was maintained at the level before infusion. In liver cirrhosis, the sinusoids were covered with continuous endothelial cells, and the number of sinusoidal endothelial fenestrae extremely decreased. ET-1 was remarkably enhanced in sinusoidal endothelial cells within the regenerating nodules, and the reaction products of ETA receptors were mainly recognized in hepatic stellate cells.. The augmented action of ET-1 via the ETA receptor may be involved in the mechanism of portal hypertension in liver cirrhosis.

Topics: Animals; Endothelial Cells; Endothelin A Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Hypertension, Portal; Immunohistochemistry; Liver; Liver Circulation; Liver Cirrhosis, Experimental; Male; Microcirculation; Microscopy, Electron, Scanning; Peptides, Cyclic; Rats; Rats, Wistar

Cirrhosis is associated with several extrahepatic manifestations including portopulmonary hypertension (PPHT). Recent data suggest that endothelins (ETs) are related to the pathophysiology of PPHT. The study aimed to measure serum ET levels in hospitalized cirrhotic patients and to determine their association with PPHT and patient outcome.. Fifty-seven cirrhotic patients [43 males; median age 58 (28-87) years] underwent Doppler echocardiography. Patients with systolic pulmonary arterial pressure ≥40 mmHg and pulmonary acceleration time <100 ms were deemed to have PPHT. ET-1, 2, and 3 serum levels were measured with an ELISA assay. All-cause mortality was recorded over a median period of 24 months.. Nine out of 57 patients (15.8%) had PPHT. Among various clinical variables, only autoimmune hepatitis was associated with PPHT (OR=11.5; 95% CI, 1.58-83.4; P=0.01). ET-1 levels [9.1 (1.6-20.7) vs 2.5 (1.4-9.2) pg/mL, P=0.02] and the ET-1/ET-3 ratio [4.73 (0.9-22.4) vs 1.6 (0.3-10.7), P=0.02] were significantly higher in patients with PPHT than in those without. ET-2 and ET-3 levels did not differ between the two groups. There was no difference in survival between the two groups, although ET-1 levels were associated with an adverse outcome in Cox regression analysis (HR=1.11; 95% CI, 1.02-1.22; P=0.02 per unit increase in ET-1).. Our data suggest that ET-1 and the ET-1/ET-3 ratio are elevated in patients with PPHT and that ET-1 is associated with a poor outcome irrespective of PPHT.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers; Chi-Square Distribution; Echocardiography, Doppler, Color; Echocardiography, Doppler, Pulsed; Endothelin-1; Endothelin-2; Endothelin-3; Endothelins; Enzyme-Linked Immunosorbent Assay; Female; Greece; Hospitalization; Humans; Hypertension, Portal; Hypertension, Pulmonary; Kaplan-Meier Estimate; Liver Cirrhosis; Logistic Models; Male; Middle Aged; Prognosis; Proportional Hazards Models; Risk Assessment; Risk Factors; Time Factors

CYP450-dependent epoxyeicosatrienoic acids (EETs) are potent arterial vasodilators, while 20-hydroxyeicosatatraenoic acid (20-HETE) is a vasoconstrictor. We evaluated their role in the control of portal circulation in normal and cirrhotic (CCl(4) induced) isolated perfused rat liver. Phenylephrine (PE) and endothelin-1 (ET-1) increased portal perfusion pressure, as did arachidonic acid (AA), 20-HETE, and 11,12-EET. Inhibition of 20-HETE with 12,12-dibromododecenoic acid (DBDD) did not affect basal pressure nor the responses to PE, ET-1, or AA. However, inhibition of epoxygenase with miconazole caused a significant reduction in the response to ET-1 and to AA, without affecting neither basal pressure nor the response to PE. Hepatic vein EETs concentration increased in response to ET-1, and was increased in cirrhotic, compared to control, livers. 20HETE levels were non-measurable. Miconazole decreased portal perfusion pressure in cirrhotic livers. In conclusion, 20HETE and EETs increase portal resistance; EETs, but not 20-HETE, mediate in part the pressure response to ET-1 in the portal circulation and may be involved in pathophysiology of portal hypertension.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Carbon Tetrachloride; Cytochrome P-450 Enzyme System; Endothelin-1; Hepatic Veins; Hydroxyeicosatetraenoic Acids; Hypertension, Portal; Infusion Pumps; Liver; Liver Cirrhosis, Experimental; Male; Miconazole; Organ Culture Techniques; Oxidoreductases; Phenylephrine; Portal Pressure; Rats; Rats, Sprague-Dawley; Vascular Resistance; Vasoconstriction; Vasodilation

Portopulmonary hypertension (PPHTN) is a rare complication in patients with portal hypertension. A role of endothelin 1 (ET-1) and other cytokines was demonstrated in primary pulmonary hypertension but not in PPHTN. We evaluated the possible role of ET-1, interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor alpha (TNF-α) in the pathogenesis of PPHTN. Plasmatic concentrations of ET-1, IL-6, IL-1β, and TNF-α were measured in patients with pulmonary systolic arterial pressure (PAPs) >30 mm Hg and in patients with cirrhosis. In all, Six out of 11 patients with PAPs >30 mm Hg had PPHTN on right heart catheterization. The remaining 10 patients had an hyperdynamic circulation (HC). In PPHTN patients, ET-1 and IL-6 were significantly higher compared with HC and patients with cirrhosis. Endothelin 1 and IL-6 could be implicated in the pathogenesis of PPHTN. On the basis of these results, ET-1 receptor antagonists or anti-IL-6 could have a rationale in the treatment of PPHTN.

Topics: Cardiac Catheterization; Cytokines; Echocardiography, Doppler, Color; Endothelin-1; Humans; Hypertension, Portal; Hypertension, Pulmonary; Interleukin-1beta; Interleukin-6; Liver Cirrhosis; Liver Transplantation; Middle Aged; Tumor Necrosis Factor-alpha

Hepatic and circulating endothelin-1 (ET-1) are increased in patients with cirrhosis and in cirrhotic animals. However, the distinct roles of ET receptor subtypes ETA and ETB in cirrhosis and portal hypertension (PHT) have not been clearly elucidated. Thus, we studied the effects of selective ET-1 antagonists (ETA-ant or ETB-ant) and nonselective ET-1 antagonist (ETA/B-ant) on hepatic hemodynamics in cirrhotic rats. Liver fibrosis and PHT were induced by complete bile duct ligation (BDL) in rats. Two weeks after BDL or sham surgery, hemodynamic responses were measured during intraportal infusion of incremental doses of the following ET-ants: (i) BQ-123, (ii) BQ-788, and (iii) bosentan. After equilibration with vehicle, doses of ET-ants were infused for 30 min periods, and steady-state systemic and hepatic hemodynamics, portal venous pressure (PVP), and hepatic blood flow (HBF) were measured. BDL induced significant PHT and elevated concentrations of plasma ET-1 compared with sham. ETA-ant decreased PVP of cirrhotic rats but had no effect on sham, whereas ETB-ant increased PVP in sham but had no effect in BDL. Nonselective ETA/B-ant decreased PVP of BDL similarly to ETA-ant. Both ETA-ant and ETB-ant decreased local HBF, whereas a nonselective antagonist did not change HBF in sham; however no significant changes were observed in HBF of BDL rats with any of the antagonists. These findings suggest ETA activation contributes to PHT in cirrhotic rats, whereas ETB-mediated portal depressor effects are attenuated in cirrhotic rats compared with noncirrhotic rats.

Topics: Animals; Antihypertensive Agents; Blood Pressure; Bosentan; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Gene Expression; Hemodynamics; Hepatic Stellate Cells; Hypertension, Portal; Liver; Liver Cirrhosis; Male; Oligopeptides; Peptides, Cyclic; Piperidines; Portal Pressure; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Regional Blood Flow; Sulfonamides

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor can enhance endothelial nitric oxide synthase expression and induce vasodilatation. The vasodilatory effect may be detrimental to portal-systemic collaterals due to aggravating the shunting degrees. The present study investigated the effects of pravastatin, a HMG-CoA reductase inhibitor, on the collateral vascular responsiveness to endothelin-1 (ET-1) and portal-systemic shunting in portal hypertensive rats.. The partial portal vein-ligated (PVL) rats received either pravastatin (25 mg/kg per day) or distilled water since 2 days prior to until 7 days after ligation. On the 8(th) day following hemodynamic measurements, the collateral vascular responsiveness to ET-1 was evaluated by an in situ collateral perfusion model. The shunting degrees of collaterals were evaluated by constructing vascular flow-pressure curves and color microsphere study, respectively. PVL rats underwent pre-incubation with: (i) Krebs solution (control); or Krebs solution plus (ii) 2 x 10(-5) M pravastatin; (iii) pravastatin + N(omega)-nitro-L-arginine (10(-4) M); and (iv) pravastatin + indomethacin (10(-5) M), followed by ET-1 (10(-10)-10(-7) M) administration to evaluate the collateral vascular responsiveness.. In chronic study, pravastatin did not modify systemic and portal hemodynamics and collateral vascular responsiveness to ET-1. The resistances of flow-pressure curves and the microsphere study demonstrated similar shunting degrees between both groups. Furthermore, pravastatin pre-incubation didn't reduce collateral perfusion pressure to ET-1.. Chronic pravastatin administration does not induce detrimental effects on hemodynamics and collaterals in PVL rats, nor does it influence the shunting degree. In addition, it does not modify the vasoconstrictive effect of ET-1 on the collaterals of PVL rats.

Topics: Animals; Collateral Circulation; Cyclooxygenase Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Enzyme Inhibitors; Hemodynamics; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hypertension, Portal; Indomethacin; Male; Nitric Oxide Synthase; Nitroarginine; Portal System; Pravastatin; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Time Factors; Vascular Resistance; Vasoconstriction; Vasoconstrictor Agents

Cirrhotic patients with portal hypertension and variceal hemorrhage are vulnerable to endotoxemia. However, the direct influence of endotoxemia on portal-systemic collateral vasculature remains unexplored. In this study, portal hypertension was induced in Sprague-Dawley rats by partial portal vein ligation. On the 7th day after portal vein ligation, at 0.5, 1.5, and 5 h post endotoxin (LPS; Escherichia coli serotype O111:B4, 3 mg/kg, i.p., E0.5, E1.5 and E5, respectively) or saline (control, C0.5, C1.5, and C5, respectively) injection, hemodynamic measurements and concentration-response relationships to arginine vasopressin (AVP; 10(-10)-10(-7) mol/L) in collateral vascular bed were obtained. In another six parallel groups, reverse-transcriptase-polymerase chain reaction of iNOS, eNOS, and endothelin 1 (ET-1) mRNA expressions for splenorenal shunt, the most prominent intra-abdominal collateral vessel, was performed. The results showed that E0.5 had lower perfusion pressure changes to AVP and higher splenorenal shunt eNOS expression than C0.5 group (P < 0.05). Compared with C1.5, tachycardia, higher perfusion pressure changes and enhanced splenorenal shunt iNOS and ET-1 expression were observed in E1.5 group (P < 0.05). In E5, systemic and portal hypotension with markedly enhanced collateral AVP responsiveness and splenorenal shunt iNOS and ET-1 expressions were noted (P < 0.05). In conclusion, vasoactive substances counterregulation participates, at least in part, the time-dependent changes of collateral AVP responsiveness in endotoxemic portal hypertensive rats.

Topics: Animals; Arginine Vasopressin; Endothelin-1; Endotoxemia; Hemodynamics; Hypertension, Portal; Lipopolysaccharides; Male; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Vasoconstrictor Agents

We have found out the clinical presentations and peculiarities of endoscopic and morphologic view of pathologies of mucous membrane of gastroduodenal zone caused by liver cirrhosis. We have examined 74 patients with liver cirrhosis of viral and nonviral etiology using the clinical, endoscopic, morphologic and immunohistochemical methods.We have found that during liver cirrhosis morphometric rates of epithelial cells of mucous coat of stomach that produce somatostatin and endothelin-1 decrease and morphometric rates of epithelial cells that produce nitrogen oxide synthase increase. We have also found out that during liver cirrhosis proliferate activity decrease and apoptosis of epithelial cell of mucous coat of stomach increase.

Topics: Adult; Apoptosis; Cell Proliferation; Duodenal Diseases; Endothelin-1; Enteroendocrine Cells; Female; Gastric Mucosa; Humans; Hypertension, Portal; Intestinal Mucosa; Liver Cirrhosis; Male; Middle Aged; Nitric Oxide Synthase; Severity of Illness Index; Somatostatin; Stomach Diseases

Thromboxane A2 (TXA2) has been suggested to play a significant role in the development of portal hypertension in fibrosis, and Kupffer cell (KC) derived TXA2 has been shown to mediate the hyperresponsiveness of the portal circulation to the vasoconstrictive actions of endothelin-1 (ET-1) during endotoxemia. The aim of this study was to determine whether the double stresses of prefibrotic changes and endotoxemia additively activate KC to increase release of TXA2 in response to ET-1, resulting in elevated portal resistance.. One week Bile duct ligation (BDL) rats and sham-operated controls were subjected to isolated liver perfusions following LPS or saline for 6h. In a separate experiment, KC were isolated from BDL or sham rats and incubated with LPS or saline for 6h before the ET-1 treatment.. The double stresses of early fibrosis and LPS resulted in a greater sustained increase in portal pressure in response to ET-1 in BDL rats, and this increase correlated well with the much enhanced release of TXA2 in the perfusate. Media from the cultured KC showed significantly greater TXA2 release in response to ET-1 in BDL group than those in sham group, and LPS exacerbated this effect. Protein levels of cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2, and thromboxane synthase were also significantly elevated in KC from BDL rats. ET-1 produced a marked increase in cPLA2 activation as measured by the phosphorylation of cPLA2 in KC of both BDL and sham groups. LPS greatly exacerbated the activation of cPLA2.. The data suggest that the double stresses additively activate KC with an upregulation of the key enzymes in the TXA2 biosynthesis and release increased amount of TXA2 via the augmented activation of cPLA2 in response to ET-1, which leads to the increased portal resistance and ultimately hepatic microcirculatory dysfunction.

Topics: Animals; Cyclooxygenase 2; Endothelin-1; Enzyme Activation; Fibrosis; Group IV Phospholipases A2; Hypertension, Portal; In Vitro Techniques; Kupffer Cells; Lipopolysaccharides; Liver; Liver Cirrhosis, Experimental; Male; Microcirculation; Phospholipases A; Phospholipases A2; Phosphorylation; Portal Pressure; Rats; Rats, Sprague-Dawley; Thromboxane A2

To investigate the effects of salvianolic acid B (SA-B) on portal hypertension induced by endothelin-1 in rats.. Twenty-eight Sprague-Dawley rats were randomly divided into four groups: ET-1 group, ET-1+SA-B group, ET-1+ET(A)R blocker (BQ-123) group and ET-1+ET(B)R blocker (BQ-788) group. The rats of ET-1+SA-B group underwent intragastrical administration of salvianolic acid B for five days before ET-1 injection, while in three other groups' drinking water was given. In BQ-123 group or BQ-788 group, an intravenous injection of BQ-123 or BQ-788 via femoral vein was administered 30 minutes prior to ET-1 injection. Then changes of portal pressure, cervical artery pressure and heart rate were monitored continuously.. After ET-1 injection, the portal pressure of all rats in the ET-1 group increased significantly, while slightly in groups that pretreated with SA-B, BQ-123 or BQ-788.. SA-B can attenuate the elevated portal pressure induced by ET-1 with effect similar to ETR blocker.

Topics: Animals; Antihypertensive Agents; Benzofurans; Drugs, Chinese Herbal; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Portal; Injections, Intravenous; Male; Oligopeptides; Peptides, Cyclic; Piperidines; Portal Pressure; Random Allocation; Rats; Rats, Sprague-Dawley

Idiopathic portal hypertension (IPH) is characterized by noncirrhotic portal hypertension due mainly to increased intrahepatic, presinusoidal resistance to portal blood flow. Marked splenomegaly is always seen in IPH. To clarify the pathogenetic significance of splenomegaly, immunohistochemical expression of inducible nitric oxide synthese (iNOS), endothelial NOS (eNOS), and endothelin-1 (ET-1) in spleens from patients with IPH was examined. Sinus lining cells of IPH spleens showed diffuse and strong expression of iNOS and eNOS. Sinus lining cells of spleens from patients with liver cirrhosis (LC) also showed positive signals for iNOS and eNOS, but the staining intensity was significantly weak. ET-1 was detectable in only a few mononuclear leukocytes in the red pulp of both IPH and LC spleens. These results suggest that NO liberated in spleen, rather than ET-1, is responsible for the dilatation of splenic sinuses, leading to splenomegaly, and thereby contributes to portal hypertension in IPH.

Topics: Aged; Endothelin-1; Female; Humans; Hypertension, Portal; Immunohistochemistry; Liver Cirrhosis; Male; Middle Aged; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Portal System; Spleen; Splenomegaly

The authors' previous report revealed that endothelin-1 might be released from B lymphocytes in cirrhotic patients with hypersplenism. Other investigators have shown that persistent exposure to environmental contaminants including arsenic might induce idiopathic portal hypertension. The aim of this study was to experimentally identify how endothelin-1 is involved in the development of idiopathic portal hypertension and which cells produce endothelin-1 in the spleen.. Portal pressure and venous endothelin-1 concentrations were measured in rats that were given sodium arsenate orally for long periods, and endothelin-1 expression levels in the spleen were assessed by staining. In a second experiment, B and T lymphocytes and monocyte-derived macrophages cultured from healthy human peripheral blood were stimulated with sodium arsenite, sodium arsenate, lipopolysaccharide and interferon-gamma. Endothelin-1 concentrations in the supernatants were measured by ELISA.. Arsenic exposure gradually increased portal pressure and venous endothelin-1 levels in rats. Endothelin-1 concentration in the supernatant did not change in every cell type stimulated with arsenic, but it increased in B lymphocytes and monocyte-derived macrophages treated with lipopolysaccharide and interferon-gamma.. The in vivo study indicated that arsenic might elevate portal pressure through mechanisms involving endothelin-1. In the in vitro study, lipopolysaccharide and interferon-gamma clearly induced endothelin-1 synthesis not only in monocyte-derived macrophages but also in B lymphocytes, although arsenic treatment did not affect those cells. This study partially supports the hypothesis that idiopathic portal hypertension might be promoted by endothelin-1 overproduction from splenic B lymphocytes in response to certain substances.

Topics: Animals; Cells, Cultured; Endothelin-1; Humans; Hypertension, Portal; Male; Rats; Rats, Sprague-Dawley

Prolonged Q-T interval (QT) has been reported in patients with cirrhosis who also exhibit profound abnormalities in vasoactive peptides and often present with elevated heart rate (HR). The aim of this study was to relate QT to the circulating level of endothelins (ET-1 and ET-3) and calcitonin gene-related peptide (CGRP) in patients with cirrhosis. In addition, we studied problems with HR correction of QT.. Forty-eight patients with cirrhosis and portal hypertension were studied during a haemodynamic investigation. Circulating levels of ETs and CGRP were determined by radioimmunoassays. Correction of QT for HR above 60 beats per min was performed using the methods described by Bazett (QT(C)) and Fridericia (QT(F)).. Prolonged QT(C) (above 440 ms), found in 56% of the patients, was related to the presence of significant portal hypertension and liver dysfunction (p < 0.05 to 0.001), but not to elevated ET-1, ET-3 or CGRP. When corrected according to Bazett, QT(C) showed no significant relation to differences in HR between patients (r = 0.07, ns). QTF showed some undercorrection of HR (r = -0.36; p < 0.02). During HR variation in the individual patient, QT(C) revealed a small but significant overcorrection (2.6 ms per heartbeat per min; p < 0.001). This value was significantly (p < 0.02) smaller with QTF (1.2 ms per heartbeat per min).. The prolonged QT(C) in cirrhosis is related to liver dysfunction and the presence of portal hypertension, but not to the elevated powerful vasoconstrictor (ET-1) or vasodilator (CGRP, ET-3) peptides. The problems with correction of the QT for elevated HR in cirrhosis are complex, and the lowest HR should be applied for determination of the QT.

Topics: Adult; Aged; Blood Pressure; Calcitonin Gene-Related Peptide; Cardiac Pacing, Artificial; Catecholamines; Electrocardiography; Endothelin-1; Endothelin-3; Endothelins; Female; Heart Rate; Hemodynamics; Humans; Hypertension, Portal; Liver Cirrhosis; Long QT Syndrome; Male; Middle Aged; Reference Values

Sinusoidal endothelial fenestrae (SEF) regulate the sinusoidal circulation by altering their diameter and number. This study documented the effects of endothelin (ET) receptor antagonists on SEF and hepatic microcirculation.. The portal pressure and hepatic tissue blood flow were measured with a hydromanometer and a laser Doppler blood flow meter, respectively. BQ-123 (ET(A) receptor antagonist) or BQ-788 (ET(B) receptor antagonist) was continuously infused into normal rats at the rate of 10 nmol/min for 10 min. The sinusoids were observed at 60 min after the infusion by scanning electron microscopy. The localization of ET-1 and ET(A) and ET(B) receptors was examined by the indirect immunoperoxidase method.. When BQ-123 was infused, the portal pressure gradually decreased with time, and it showed a significant reduction compared with the control groups. On the other hand, a decrease in portal pressure was not evident in the BQ-788-infused groups. Hepatic tissue blood flow was maintained at the value prior to the infusion in both groups. BQ-123 also caused a marked dilatation of the SEF. The diameters of the SEF after BQ-123 infusion were almost three times those of normal SEF. ET-1 was evenly present along the sinusoidal walls, and the reaction products of the ET(A) receptors were recognized along the portal vein and in the sinusoidal cells, that is, the hepatic stellate cells and endothelial cells.. Action of ET-1 via the ET(A) receptors may regulate the size of SEF in addition to hepatic microcirculation.

Topics: Animals; Antihypertensive Agents; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Hypertension, Portal; Immunohistochemistry; Liver; Liver Circulation; Male; Microcirculation; Microscopy, Electron, Scanning Transmission; Peptides, Cyclic; Rats; Rats, Wistar; Vasodilation

Topics: Endothelin-1; Humans; Hypertension, Portal; Hypertension, Pulmonary; Liver Cirrhosis

In liver cirrhosis atrial natriuretic peptide (ANP) decreases portal vascular resistance and tributary flow. The enzyme neutral endopeptidase (NEP) degrades ANP and bradykinin and generates endothelin-1 from big-endothelin. We determined the effects of NEP inhibition by candoxatrilat on hormonal status, liver function and arterial and portal pressures in rats with CCl4-induced cirrhosis.. Two groups of seven control rats received 1 ml 5% glucose solution alone or containing 10 mg/kg candoxatrilat; three groups of 10 ascitic cirrhotic rats received placebo, 5 or 10 mg/kg candoxatrilat. NEP protein concentration and immunostaining were analyzed in normal and cirrhotic livers.. In cirrhotic rats 10 mg/kg candoxatrilat significantly increased steady-state indocyanine green clearance (a parameter reflecting liver plasma flow) (P<0.01), decreased portal pressure (P<0.01), had no effect on arterial pressure and plasma renin activity but increased ANP plasma levels (P<0.05) and urinary excretions (P<0.01) of ANP and cGMP. In the cytosol fraction of rat cirrhotic livers a 280% increase in NEP content was found (P<0.01), chiefly localized in desmin-positive myofibroblast-like cells of fibrous septa.. Candoxatrilat has few effects on systemic hemodynamics and hormonal status; its portal hypotensive action depends on effects exerted on intrahepatic vascular resistance.

Topics: Animals; Arginine Vasopressin; Atrial Natriuretic Factor; Blood Pressure; Carbon Tetrachloride; Cyclic GMP; Cyclohexanecarboxylic Acids; Cytokines; Endothelin-1; Humans; Hypertension, Portal; Liver; Liver Cirrhosis, Experimental; Male; Neprilysin; Portal Vein; Protease Inhibitors; Rats; Rats, Wistar; Vascular Resistance

Rats with chronic bile duct ligation (CBDL) and portal vein ligation (PVL) are used as models of portal hypertension. CBDL rats show hypoxemia with intrapulmonary vasodilatation (IPVD), and are recognized as a model of hepatopulmonary syndrome (HPS), while PVL rats are normoxemic. We investigated the differences in arterial oxygenation between these models, and the key factors leading to HPS.. Forty-eight Sprague-Dawley rats were prepared as CBDL or PVL models, or as Sham rats. Arterial oxygenation, hemodynamics (reference sample method), and IPVD were simultaneously evaluated in conscious and unrestrained animals, using (141)Ce- or (113)Sn-labeled microspheres (15 microm in diameter), respectively. Endothelin-1 (ET-1) and nitrate/nitrite (end products of nitric oxide; NOx) production by the lung tissue (increment across the lungs) was also determined.. The extent of IPVD was similar in both models, but hypoxemia was only observed in CBDL rats. The ET-1 level and the increment in NOx were significantly increased in CBDL rats, and the increment was directly correlated with impairment of oxygenation. Blood flow through the bronchial arteries (anatomical shunting) was increased in CBDL rats, reaching more than three times the level in PVL rats or Sham rats.. These results support the hypothesis that NO derived from the lung tissues contributes to hypoxemia, and IPVD appears to be a prerequisite for impaired oxygenation. The considerable increase of anatomical shunting may potentially contribute to impaired oxygenation in CBDL rats.

Topics: Animals; Arteries; Disease Models, Animal; Endothelin-1; Hepatopulmonary Syndrome; Hypertension, Portal; Hypoxia; Lung; Male; Microspheres; Nitrates; Nitrites; Oxygen; Rats; Rats, Sprague-Dawley; Vasodilation

It is postulated that nitric oxide (NO) is responsible for the hyperdynamic circulation of portal hypertension. Therefore, we investigated induction of fibrosis and hyperdynamic circulation in endothelial NO synthase knock-out (KO) mice.. Fibrosis was induced by bile duct ligation. Hemodynamic studies were performed after portal vein ligation. All studies were performed in wild-type (WT) and KO mice.. Three to 4 weeks after bile duct ligation (BDL), both WT and KO groups had similar degrees of portal hypertension, 12 (9-14) and 11(8-15) mmHg, median (range), and liver function. Fibrosis increased from 0.0% in sham operated to 1.0 and 1.1% in WT and KO mice, respectively. Cardiac output was similar after portal vein ligation (20 and 17 ml/min in WT and KO mice, respectively). There was no difference in liver of mRNA for endothelin 1, inducible NO synthase (iNOS) and hem-oxygenase 1 (HO1); proteins of iNOS, HO1 and HO2; nor in endothelin A and B (EtA and EtB) receptor density between WT and KO mice after BDL.. These results suggest that endothelial NO synthase is neither essential for the development of fibrosis and portal hypertension in bile duct ligated mice, nor for the hyperdynamic circulation associated with portal hypertension in the portal vein ligated mice.

Topics: Animals; Bile Ducts; Disease Models, Animal; Endothelin-1; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hypertension, Portal; Ligation; Liver; Liver Cirrhosis; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase Type III; RNA, Messenger

Common bile duct ligation (CBDL) triggers a molecular cascade resulting in the hepatopulmonary syndrome (HPS). Both increased hepatic endothelin-1 (ET-1) production and pulmonary vascular ET(B) receptor expression with stimulation of endothelial nitric oxide synthase and TNF-alpha mediated inducible nitric oxide synthase and heme oxygenase-1 expression in pulmonary intravascular macrophages occur. Whether biliary cirrhosis is unique in triggering ET-1 and TNF-alpha alterations and HPS is unknown. We evaluated for HPS in rat prehepatic portal hypertension [partial portal vein ligation (PVL)], biliary (CBDL) and nonbiliary [thioacetamide treatment (TAA)] cirrhosis, and assessed ET-1 infusion in normal and PVL animals. Control, PVL, CBDL, TAA-treated, and ET-1-infused PVL animals had ET-1 and TNF-alpha levels measured and underwent molecular and physiological evaluation for HPS. HPS developed only in biliary cirrhosis in association with increased plasma ET-1 and TNF-alpha levels and the development of established molecular changes in the pulmonary microvasculature. In contrast, PVL did not increase ET-1 or TNF-alpha levels and TAA treatment increased TNF-alpha levels alone, and neither resulted in the full development of molecular or physiological changes of HPS despite portal pressure increases similar to those after CBDL. Exogenous ET-1 increased TNF-alpha levels and triggered HPS after PVL. Combination of ET-1 and TNF-alpha overproduction is unique to biliary cirrhosis and associated with experimental HPS. ET-1 infusion increases TNF-alpha levels and triggers HPS in prehepatic portal hypertension. ET-1 and TNF-alpha interact to trigger pulmonary microvascular changes in experimental HPS.

Topics: Animals; Endothelin-1; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Hepatopulmonary Syndrome; Hypertension, Portal; Ligation; Liver Cirrhosis; Liver Cirrhosis, Biliary; Lung; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Portal Vein; Rats; Rats, Sprague-Dawley; Thioacetamide; Tumor Necrosis Factor-alpha

To evaluate the effect of tumor necrosis factor (TNF), endothelin (ET) and nitric oxide (NO) on hyperdynamic circulation (HC) of rats with acute and chronic portal hypertension (PHT).. Chronic portal hypertension was induced in Wistar rats by injection of carbon tetrachloride. After two weeks of cirrhosis formation, L-NMMA (25 mg/kg) was injected into one group of cirrhotic rats via femoral vein and the experiment was begun immediately. Another group of cirrhotic rats was injected with anti-rat TNFalpha (300 mg/kg) via abdominal cavity twice within 48 h and the experiment was performed 24 h after the second injection. The blood concentrations of TNFalpha, ET-1 and NO in portal vein and the nitric oxide synthase (NOS) activity in hepatic tissue were determined pre-and post-injection of anti-rat TNFalpha or L-NMMA. Stroke volume (SV), cardiac output (CO), portal pressure (PP), superior mesenteric artery blood flow (SMA flow) and iliac artery blood flow (IAflow) were measured simultaneously. Acute portal hypertension was established in Wistar rats by partial portal-vein ligation (PVL). The parameters mentioned above were determined at 0.5 h, 24 h, 48 h, 72 h and 120 h after PVL. After the formation of stable PHT, the PVL rats were injected with anti-rat TNFalpha or L-NMMA according to different groups, the parameters mentioned above were also determined.. In cirrhotic rats, the blood levels of TNFalpha, NO in portal vein and the liver NOS activity were significantly increased (P<0.05) while the blood level of ET-1 was not statistically different (P>0.05) from the control animals (477.67+/-83.81 pg/mL vs 48.87+/-32.79 pg/mL, 278.41+/-20.11 micromol/L vs 113.28+/-14.51 micromol/L, 1.81+/-0.06 u/mg.prot vs 0.87+/-0.03 u/mg.prot and 14.33+/-4.42 pg/mL vs 8.72+/-0.79 pg/mL, respectively). After injection of anti-rat TNFalpha, the blood level of TNFalpha was lower than that in controls (15.17+/-18.79 pg/mL vs 48.87+/-32.79 pg/mL). The blood level of NO and the liver NOS activity were significantly decreased, but still higher than those of the controls. The blood level of ET-1 was not significantly changed. PP, SV, CO, SMAflow and IAflow were ameliorated. After injection of L-NMMA, the blood level of NO and the liver NOS activity were recovered to those of the controls. PP and CO were also recovered to those of the controls. SV, SMAflow and IAflow were ameliorated. In PVL rats, the blood levels of TNFalpha, NO in portal vein and the liver NOS activity were gradually increased and reached the highest levels at 48 h after PVL. The blood level of ET-1 among different staged animals was not significantly different from the control animals. PP among different staged animals (2.4+/-0.18 kPa at 0.5 h, 1.56+/-0.08 kPa at 24 h, 1.74+/-0.1 kPa at 48 h, 2.38+/-0.05 kPa at 72 h, 2.39+/-0.16 kPa at 120 h) was significantly higher than that in controls (0.9+/-0.16 kPa). After injection of anti-rat TNFalpha in 72 h PVL rats, the blood level of TNFalpha was lower than that in controls (14+/-14 pg/mL vs 48.87+/-32.79 pg/mL). The blood level of NO and the liver NOS activity were significantly decreased, but still higher than those of the controls. The blood level of ET-1 was not significantly changed. PP was decreased from 2.38+/-0.05 kPa to 1.68+/-0.12 kPa, but significantly higher than that in controls. SV, CO, SMAflow and IAflow were ameliorated. After injection of L-NMMA in 72 h PVL rats, the blood level of NO and the liver NOS activity were recovered to those of the controls. PP, SV, CO, SMAflow and IAflow were also recovered to those of the controls.. NO plays a critical role in the development and maintenance of HC in acute PHT and is a key factor for maintenance of HC in chronic PHT. TNFalpha may not participate in the hemodynamic changes of HC directly, while play an indirect role by inducing the production of NO through activating NOS. No evidence that circulating ET-1 plays a role in both models of portal hypertension has been found.

Topics: Acute Disease; Animals; Antineoplastic Agents; Chronic Disease; Endothelin-1; Enzyme Inhibitors; Hypertension, Portal; Liver; Liver Circulation; Male; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Portal Vein; Rats; Rats, Wistar; Tumor Necrosis Factor-alpha

Endothelin-1 (ET-1) may induce intrahepatic vasoconstriction and consequently increase portal pressure. Endothelin-1 has been shown to exert a direct vasoconstrictive effect on the collateral vessels in partially portal vein-ligated rats with a high degree of portal-systemic shunting. This study investigated the collateral vascular responses to ET-1, the receptors in mediation and the regulation of ET-1 action by nitric oxide and prostaglandin in cirrhotic rats with a relatively low degree of portal-systemic shunting.. The portal-systemic collaterals of common bile duct-ligated (BDL) cirrhotic rats were tested by in situ perfusion. The concentration-response curves of collaterals to graded concentrations of ET-1 (10(-10)-10(-7) m) with or without BQ-123 (ET(A) receptor antagonist, 2 x 10(-6) m), BQ-788 (ET(B) receptor antagonist, 10(-7) m) or both were recorded. In addition, the collateral responses to ET-1 with preincubation of N(omega)-nitro-L-arginine (NNA, 10(-4) M), indomethacin (INDO, 10(-5) M) or in combination were assessed.. Endothelin-1 significantly increased the perfusion pressures of portal-systemic collaterals. The ET-1-induced constrictive effects were inhibited by BQ-123 or BQ-123 plus BQ-788 but not by BQ-788 alone. The inhibitory effect was greater in the combination group. Pretreatment of NNA or NNA plus INDO equivalently enhanced the response of ET-1 while pretreatment of INDO alone exerted no effect.. Endothelin-1 has a direct vasoconstrictive effect on the collaterals of BDL cirrhotic rats, mainly mediated by ET(A) receptor. Endogenous nitric oxide may play an important role in modulating the effects of ET-1 in the portal-systemic collaterals of BDL cirrhotic rats.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Antihypertensive Agents; Collateral Circulation; Common Bile Duct; Endothelin Receptor Antagonists; Endothelin-1; Enzyme Inhibitors; Hypertension, Portal; Indomethacin; Ligation; Liver Cirrhosis, Experimental; Male; Nitric Oxide; Nitroarginine; Oligopeptides; Peptides, Cyclic; Piperidines; Portal System; Prostaglandin Antagonists; Rats; Rats, Sprague-Dawley; Vasoconstriction; Vasoconstrictor Agents

Hepatic concentrations of the powerful vasoconstrictor and fibrogen endothelin 1 (ET-1) and its receptors increase in human and experimental cirrhosis, suggesting a major role for ET-1 in the pathology of chronic liver disease. We investigated whether ET-1 receptor antagonism, after the development of fibrosis and cirrhosis, arrests/reverses the progression of chronic liver disease.. Chronic liver injury was induced in rats by carbon tetrachloride (CCl(4)) treatment (0.15 ml/kg intraperitoneally twice a week) in conjunction with phenobarbital in drinking water (0.4 g/l) for four (group 1: fibrosis) and eight (group 2: cirrhosis) weeks. Rat were then treated concurrently with the ET-1 receptor antagonist TAK-044 (10 mg/kg/day) and CCl(4)/phenobarbital for a further four weeks.. Histopathological examination revealed significant arrest of progression to cirrhosis in group 1 and reversal of cirrhosis in group 2 rats. TAK-044 treatment caused significant amelioration of portal hypertension, systemic hypotension, and liver injury (reduced activities of serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase), and improved hepatic synthetic capacity (increased serum albumin concentration) in both groups of rats relative to vehicle treated rats. TAK-044 treatment reduced collagen synthesis, as evidenced by decreased hepatic hydroxyproline content, mRNA expression of collagen-alpha type I, and tissue inhibitors of matrix metalloproteinases 1 and 2, and mRNA and protein expression of a potent fibrogenic cytokine, transforming growth factor beta1.. The results emphasise the role of ET-1 in the development of cirrhosis and strongly suggest that blockade of its actions can be a rational therapy for chronic liver disease and its complications.

Topics: Animals; Carbon Tetrachloride; Disease Progression; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Portal; Liver; Liver Cirrhosis, Experimental; Male; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptors, Endothelin

To investigate whether low-dose nitric oxide donor FK 409 could attenuate small-for-size graft injury in liver transplantation using small-for-size grafts.. The major concern of live donor liver transplantation is small-for-size graft injury at the early phase after transplantation. Novel therapeutic strategies should be investigated.. We employed a rat orthotopic liver transplantation model using small-for-size (40%) graft. FK 409 was given at 30 minutes before graft harvesting (2 mg/kg) to the donor and immediately after reperfusion (1 mg/kg) to the recipient (FK group). Graft survival, intragraft genes expression, portal hemodynamics, and hepatic ultrastructural changes were compared between the 2 groups.. Seven-day graft survival rates in the FK group were significantly improved compared with those of rats not receiving FK 409 (control group; 80% versus 28.6%, P = 0.018). In the FK group, portal pressure was significantly decreased within the first 60 minutes after reperfusion whereas in the control group, transient portal hypertension was observed. Intragraft expression (both mRNA and protein) of early growth response-1, endothelin-1, endothelin-1 receptor A, tumor necrosis factor-alpha, macrophage-inflammatory protein-2, and inducible nitric oxide synthase was significantly down-regulated accompanied with up-regulation of heme oxygenase-1, A20, interferon-gamma-inducible protein-10, and interleukin-10 during the first 24 hours after reperfusion. Hepatic ultrastructure, especially the integrity of sinusoids was well protected in the FK group.. Low-dose FK 409 rescues small-for-size grafts in liver transplantation by attenuation of portal hypertension and amelioration of acute phase inflammatory response by down-regulation of Egr-1, together with prior induction of heat shock proteins.

Topics: Animals; Apoptosis; Chemokine CXCL2; Chemokines; Chemokines, CXC; DNA-Binding Proteins; Down-Regulation; Early Growth Response Protein 1; Endothelin-1; Gene Expression; Graft Survival; Heat-Shock Proteins; Heme Oxygenase (Decyclizing); Hypertension, Portal; Immediate-Early Proteins; Intercellular Signaling Peptides and Proteins; Liver; Liver Transplantation; Male; Nitric Oxide Donors; Nitro Compounds; Oxygenases; Preoperative Care; Proteins; Rats; Rats, Inbred Lew; Reperfusion; RNA, Messenger; Signal Transduction; Tissue and Organ Harvesting; Tissue Donors; Transcription Factors; Zinc Fingers

Topics: Cytokines; Endothelin-1; Humans; Hypertension, Portal; Hypertension, Pulmonary

To study whether liver cirrhosis and portal hypertension are associated with ET-1 TaqI polymorphism and TNFa promoter-308G to A polymorphism.. A case control study of 106 patients with liver cirrhosis following HBV C infection was performed in comparison with 108 controls by PCR-RFLP.. The frequency of C allele and CC+TC genotype in TaqI polymorphism of ET-1 gene in the portal hypertension group (LC+) was significantly higher than that in the healthy controls, and the frequency of TNF2/1 genotype in TNFa promoter -308 G to A polymorphism in LC+ group was significantly higher than that in the control group. The results by stratification analysis showed that TCF2 genotype frequency was higher in the LC+ group than in the control group. ET-1 TaqI polymorphism and TNFa polymorphism were risk factors for the occurrence of portal hypertension by Logistic regression analysis.. ET-1 TaqI polymorphism and TNFa polymorphism are associated with portal hypertension, and are new risk factors for the occurrence of portal hypertension. TCF2 genotype may be a susceptible gene of portal hypertension.

Topics: Adult; Case-Control Studies; Endothelin-1; Female; Gene Frequency; Hepatitis B, Chronic; Humans; Hypertension, Portal; Liver Cirrhosis; Male; Middle Aged; Polymerase Chain Reaction; Polymorphism, Genetic; Polymorphism, Restriction Fragment Length; Promoter Regions, Genetic; Taq Polymerase; Tumor Necrosis Factor-alpha

To investigate the degree and mechanism of hepatic sinusoidal injury in different graft sizes in right lobe live donor liver transplantation (LDLT).. Liver grafts from living donors are likely to be small-for-size for adult recipients. Graft injury after reperfusion is common, but the mechanism and degree of injury remain unclear. The hepatic sinusoidal injury in different graft sizes and its relationship with portal hemodynamics and intragraft gene response at the early phase after reperfusion have not been studied in right lobe LDLT.. From May 2000 to November 2001, 40 adults receiving right lobe LDLT had portal pressure measured continuously before and after reperfusion. Liver biopsies were taken before and after reperfusion for detection of vasoregulatory genes (endothelin-1 and endothelial nitric oxide synthase) and heat shock genes (heat shock protein 70 and heme oxygenase-1), and electron microscope examination. Blood samples from the portal vein and suprahepatic inferior vena cava were taken for the measurement of plasma nitric oxide level.. The recipients were grouped according to the ratio of graft weight to estimated standard liver weight: group 1 (n = 10), less than 40%; group 2 (n = 21), 40% to 60%; and group 3 (n = 9), more than 60%. The portal pressures recorded after reperfusion in group 1 were significantly higher within 30 minutes of reperfusion than those in groups 2 and 3. After reperfusion, the intragraft endothelin-1 mRNA level in group 1 increased by 161% of the basal level but decreased by 31.5% and 62% of the basal level in groups 2 and 3, respectively. The intragraft mRNA level of heme oxygenase-1 in groups 1 and 2 decreased by 75.5% and 25.3% of the basal level respectively but increased by 41% of basal level in group 3. The intragraft protein level of heat shock protein 70 decreased by 50 ng/mL after reperfusion in group 1 but increased by 12.4 ng/mL and 0.6 ng/mL in groups 2 and 3, respectively. The portal vein plasma nitric oxide level decreased more significantly after reperfusion in group 1 than in group 2. Electron microscope examination of liver biopsies in group 1 showed tremendous mitochondrial swelling as well as irregular large gaps between the sinusoidal lining cells. There were two hospital deaths in group 1 and none in the other two groups.. Patients implanted with grafts less than 40% of standard liver weight suffered from transient portal hypertension early after reperfusion. The phenomenon was accompanied by intragraft upregulation of endothelin-1 and ultrastructural evidence of sinusoidal damage. The transient portal hypertension after reperfusion, subsequent endothelin-1 overexpression, and plasma nitric oxide level reduction, together with downregulation of heme oxygenase-1 and heat shock protein 70, may account for the small-for-size graft injury.

Topics: Adolescent; Adult; Aged; Endothelin-1; Female; Gene Expression Regulation; Heme Oxygenase (Decyclizing); Hemodynamics; HSP70 Heat-Shock Proteins; Humans; Hypertension, Portal; Liver; Liver Circulation; Liver Transplantation; Living Donors; Male; Middle Aged; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Organ Size; Portal System; Reperfusion Injury; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Transplants

In experimental hepatopulmonary syndrome (HPS), hepatic endothelin-1 (ET-1) release during common bile duct ligation (CBDL) and ET-1 infusion in pre-hepatic portal hypertension after portal vein ligation (PVL) initiate vasodilatation through an endothelin B receptor mediated increase in pulmonary endothelial nitric oxide synthase (eNOS). We evaluated if pulmonary ET receptor expression changes in experimental cirrhosis and portal hypertension and confers susceptibility to HPS.. In normal, PVL and CBDL animals, lung ET receptor expression and localization were assessed and ET receptor levels and functional analysis of ET-1 effects on eNOS levels were evaluated in intralobar pulmonary artery (PA) and aortic (AO) segments. Normal rats underwent evaluation for HPS after ET-1 infusion.. There was a selective increase in ET(B) receptor expression in the pulmonary vasculature from PVL and CBDL animals. ET-1 stimulated NO production and an ET(B) receptor mediated increase in eNOS levels in PA segments from PVL and CBDL animals, but not normal animals. ET-1 did not alter lung eNOS levels or cause HPS in normal rats.. ET(B) receptor expression and ET-1 mediated eNOS and NO production are enhanced in the lung vasculature in cirrhotic and portal hypertensive animals and correlate with in vivo susceptibility to ET-1 mediated HPS.

Topics: Animals; Common Bile Duct; Endothelin-1; Endothelium, Vascular; Hepatopulmonary Syndrome; Hypertension, Portal; Ligation; Liver Cirrhosis; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Portal Vein; Pulmonary Artery; Pulmonary Circulation; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B

Biliary atresia (BA) is a severe neonatal liver disease characterized by progressive extrahepatic biliary tract and intrahepatic inflammatory process. Hepatic fibrosis and portal hypertension (PH) still occur despite the disappearance of jaundice following successful hepatic portoenterostomy. Endothelin-1 (ET-1) is a potent vasoconstrictor and has been reported to stimulate hepatic collagen synthesis. The aim of this study was to demonstrate the potential role of ET-1 in the pathogenesis of the progressive inflammation, fibrosis and PH in BA.. Thirty pediatric patients with biliary atresia post-hepatic portoenterostomy and 12 healthy children were examined. The ET-1 level was determined by commercially available enzyme-linked immunosorbent assay kits.. Endothelin-1 levels were elevated in the patients compared with those of the controls (5.45+/-3.34 vs. 2.74+/-2.17 pg/ml, P = 0.01). Moreover, patients with PH also had greater levels of ET-1 than those without PH (6.73+/-3.27 vs. 3.26+/-2.2 pg/ml, P = 0.004). Patients with abnormal transaminase enzymes had significantly higher ET-1 levels than those with normal enzymes (6.43+/-3.33 vs. 3.17+/-2.1 pg/ml, P = 0.01). In the jaundice-free group, endothelin-1 levels were elevated in the patients with PH compared with those without PH (5.93+/-2.15 vs. 2.88+/-2.1 pg/ml, P = 0.02).. Our findings showed elevation of plasma ET-1 levels in patients with BA, especially in those with PH. ET-1 levels were also higher in patients with elevated transminase enzymes as well as in the jaundice-free group with PH. ET-1 might play a role in the pathogenesis of the progressive inflammation, fibrosis and PH in BA.

Topics: Biliary Atresia; Child; Child, Preschool; Disease Progression; Endothelin-1; Female; Fibrosis; Humans; Hypertension, Portal; Infant; Male

To investigate the correlation between polymorphism of TaqI of endothelin (ET)-1 gene intron 4 and cirrhotic portal hypertension and to search new risk factor of portal hypertension.. Peripheral venous blood was extracted from 106 patients with cirrhosis after hepatitis B (PH+ group) and 108 healthy blood donors (PH- group). PCR-RFLP was used to analyze the polymorphism of TaqI of ET-1 gene. The plasma ET-1 concentration was detected with immunoassay. Multivariate logistic regression analysis was made to analyze the risk factors.. The C allele frequency in the PH+ group was 25.4%, significantly higher than that of the controls (16.7%, P < 0.05). The frequency of CC + TC genotype in PH+ group was 46.2%, significantly lower than that in the controls (29.6%, P < 0.05). In the PH+ group, the thickness of spleen was greater, hemorrhage rate was higher, and III degrees ascites was more in C allele carrier than in T allele carriers (P < 0.05). The plasma ET-1 concentration was higher in PH+ group than in PH- group. In the PH+ group, the plasma ET-1 concentrations in those with CC genotype and those with TC genotype were significantly higher than in those with TT genotype (P < 0.05). Correlation analysis showed that ET-1 gene polymorphism was positively correlated with plasma ET-1 concentration (R = 0.808 2). Multivariate logistic regression analysis showed that gradation of liver function, diameter of portal vein, and ET-1 gene polymorphism were independent risk factors of portal hypertension.. Polymorphism of TaqI of ET-1 gene is correlated with the pathogenesis of cirrhotic portal hypertension. It may be one of the risk factors of portal hypertension.

Topics: Adult; Deoxyribonucleases, Type II Site-Specific; Endothelin-1; Female; Humans; Hypertension, Portal; Liver Cirrhosis; Logistic Models; Male; Middle Aged; Polymorphism, Genetic

The prevalence of portopulmonary hypertension (PPHTN) in patients with cirrhosis and refractory ascites is unknown. Its presence may preclude patients from receiving a transjugular intrahepatic portosystemic shunt or liver transplantation as a definitive treatment for their end stage cirrhosis.. To determine the prevalence, possible aetiological factors, and predictive factors for the development of PPHTN in these patients.. Sixty two patients (53 males, nine females; mean age 54.5 (1.4) years) with biopsy proven cirrhosis and refractory ascites underwent angiographic measurements of pulmonary and splanchnic haemodynamics. Endothelin 1 levels were measured from the pulmonary artery. Forty nine patients underwent radionuclide angiography for measurements of central blood volume, pulmonary vascular, and cardiac chamber volumes. Forty seven patients also underwent two dimensional echocardiography for measurements of cardiac structural and functional parameters. Cardiac output, and systemic and pulmonary vascular resistance were calculated.. Ten patients (16.1%) fulfilled the criteria for PPHTN (mean pulmonary artery pressure >/= 25 mm Hg and pulmonary vascular resistance >/= 120 dynxs/cm(5)), with significantly higher mean right atrial (15.4 (1.2) v 7.9 (0.5) mm Hg; p<0.001), and right ventricular pressures (24.7 (1.5) v 14.7 (0.6) mm Hg; p<0.001), and endothelin 1 levels (3.04 (0.40) v 1.98 (0.12) pg/ml; p=0.02). No significant differences in any of the other parameters measured were detected between the two groups. A right atrial pressure of >/= 14 mm Hg had a 83% positive predictive value for the presence of PPHTN.. Portopulmonary hypertension is common in cirrhosis with refractory ascites, possibly due to excess endothelin 1 in the pulmonary circulation. An elevated right atrial pressure >/= 14 mm Hg predicts the presence of PPHTN, which may be helpful in deciding management options in these patients.

Topics: Ascites; Echocardiography; Endothelin-1; Female; Heart Atria; Humans; Hypertension, Portal; Hypertension, Pulmonary; Liver Cirrhosis; Male; Middle Aged; Radionuclide Angiography

Thromboxane A2 (TXA2) and endothelin-1 (ET-1) have been proposed as the important vasoconstrictors that increase portal venous resistance in paracrine or autocrine fashion. We hypothesized that the hepatic damage following trauma-hemorrhage (T-H) is induced by the impaired hepatic circulation due to the increased production of vasoconstrictors such as ET-1 and TXA2 by the liver. To test this, male Sprague-Dawley rats (n = 6/group) were subjected to trauma (i.e., midline laparotomy) and hemorrhage (35-40 mmHg for 90 min followed by fluid resuscitation) or sham operation. At 2 or 5 h after the end of resuscitation, the liver was isolated and perfused and portal inflow pressure, bile flow, and release of ET-1 and thromboxane B2 (TXB2; a stable metabolite of TXA2) into the perfusate were measured. The level of portal pressure was higher at 5 h following T-H compared with 2 h after T-H and sham. The portal pressure was inversely correlated to the amount of bile production. Furthermore, the bile flow was significantly correlated to the hepatic damage as evidenced by release of lactate dehydrogenase into the perfusate. The level of ET-1 at 5 h following T-H in the perfusate after 30 min of recirculation did not show any difference from sham. However, the levels of TXB2 in the T-H group were significantly higher than those in sham at that interval. These results indicate that the increased release of TXA2 but not ET-1 following T-H might be responsible for producing the increased portal resistance, decreased bile production, and hepatic damage.

Topics: Abdominal Injuries; Alanine Transaminase; Animals; Bile; Endothelin-1; Hemorrhage; Hypertension, Portal; In Vitro Techniques; L-Lactate Dehydrogenase; Liver; Male; Perfusion; Portal Vein; Rats; Rats, Sprague-Dawley; Thromboxane A2; Thromboxane B2; Venous Pressure; Wounds, Penetrating

Topics: Child; Endothelin-1; Hemodynamics; Humans; Hypertension, Portal; Kidney; Liver Cirrhosis; Renal Circulation

Plasma endothelin-1 (ET-1) is a potent vasoconstrictor peptide involved in the pathogenesis of several disorders. Endothelin-1 concentrations are increased in adult patients with cirrhosis. However, little is known about ET-1 concentrations in children with cirrhosis.. Radioimmune assay was used to measure plasma ET-1 concentrations in 19 children with cirrhosis (8 patients with ascites, and 11 without ascites), and 11 age- and sex-matched healthy children. The plasma ET-1 concentrations were correlated with the mean blood pressure, creatinine clearance, and severity of portal hypertension, as measured by portal flow volume and portal flow velocity.. Patients with cirrhosis and ascites had increased plasma ET-1 concentrations compared with patients who did not have ascites (6.8 pg/mL +/- 0.62 pg/mL vs. 4.6 pg/mL +/- 0.35 pg/mL; mean +/- SEM; < 0.01) and controls (3.6 pg/mL +/- 0.27 pg/mL; mean +/- SEM; < 0.0005). Plasma ET-1 concentrations were higher in patients with cirrhosis who did not have ascites compared with controls ( < 0.005). No significant differences were observed between concentrations of the patients with cholestasis and those without cholestasis (5.4 pg/mL +/- 0.52 pg/mL vs. 5.2 +/- 0.32 pg/mL; mean +/- SEM; = 0.1). Plasma ET-1 concentrations correlated positively with the mean blood pressure ( = 0.58; < 0.05) and negatively with renal function, as measured by creatinine clearance ( = -0.7; <0.005). However, no correlation was detected between ET-1 concentrations and portal flow volume ( = -0.02; = 0.4) or portal flow velocity ( = -0.16; = 0.4).. Plasma ET-1 concentrations are increased in children with cirrhosis, with or without ascites, compared with controls. Patients with cirrhosis and ascites have increased ET-1 concentrations compared with those without ascites. The degree of increase does not relate to the severity of portal hypertension. This increase tends to maintain systemic blood pressure but is associated with a decrease in renal function.

Topics: Ascites; Blood Pressure; Case-Control Studies; Child; Cholestasis; Creatinine; Endothelin-1; Female; Humans; Hypertension, Portal; Kidney; Liver Cirrhosis; Male; Radioimmunoassay; Renal Circulation

Patients with cirrhosis and portal hypertension have a hyperkinetic systemic circulation. A number of circulating vasoactive peptides, including endothelin-1 (ET-1), are elevated and, recently, increased arterial compliance has been described in these patients. The aim of the present study was to investigate a potential relation between altered arterial compliance and arterial ET-1 in patients with cirrhosis. As ET-1 may be manipulated by somastostatin, the study includes infusion of octreotide in a subset of patients.. A total of 67 patients with cirrhosis and 27 controls were studied during a haemodynamic investigation. Arterial ET-1 was determined by two different radioimmunoassays and arterial compliance was determined as the stroke volume/pulse pressure index.. Arterial compliance was elevated by 32%-40% in the cirrhotic patients as compared to the controls (P < 0.005). Arterial ET-1 was elevated by 26%-170% in the cirrhotic patients (P<0.001). No significant relationships could be established between arterial compliance and arterial ET-1 (r = -0.15 to 0.23, ns). Intravenous bolus injection and infusion of octreotide (100 pg + 100 microg/h, n = 9) did not significantly change either arterial compliance or arterial ET-1.. Both arterial compliance and arterial ET- I are substantially elevated in patients with cirrhosis, but there is no significant relation between arterial compliance and arterial ET- I in these patients.

Topics: Adult; Aged; Arteries; Endothelin-1; Female; Hemodynamics; Humans; Hypertension, Portal; Liver Cirrhosis; Male; Middle Aged; Octreotide; Vasoconstrictor Agents

To investigate the effects of ET-1 on isolated perfused rat liver and vascular rings at early and late stages of cirrhosis.. Liver cirrhosis was induced by an intraperitoneal injection of 50% CCl(4) (0.3 ml/100 g, twice a week). In the 9th and 14th weekend after injecting CCl(4), the isolated perfused liver and vascular rings were performed to evaluate effects of four concentrations of ET-1 on early and late stages of cirrhosis.. The Ppv of L-HC group at baseline was higher than that of E-HC group, both were higher than that of the controls. However, there showed no differences on Phv in these groups. With the concentration of ET-1 increasing, PVP was elevated accordingly in E-HC and L-HC group. L-HC group showed higher PVP compared with E-HC group, both were higher than the controls. While in isolated vascular rings, with the deteriorating of cirrhosis, the cumulative response curves showed right-shift. 0.1 nmol/L ET-1 showed mild relaxation on vascular rings in L-HC group.. ET-1 can increase the PVP, especially with the deterioration of cirrhosis, there showed higher reaction compared with normal controls. The vascular rings showed low response on the contrary. So ET-1 plays an important role in the pathogenesis of portal hypertension. In view of its different roles on liver and vascular rings at early and late stages, administration of different selective antagonist of ET receptor at different stages of cirrhosis should be well considered.

Topics: Animals; Carbon Tetrachloride; Dose-Response Relationship, Drug; Endothelin-1; Hypertension, Portal; In Vitro Techniques; Liver; Liver Cirrhosis; Male; Perfusion; Portal Vein; Rats; Rats, Sprague-Dawley; Vasoconstriction

Somatostatin and its long-acting analogue, octreotide, have been used to cease variceal bleeding with uncertain mechanisms. This study investigated whether somatostatin and octreotide have a direct vasoconstrictive effect on the portal-systemic collaterals of portal-hypertensive rats and potentiate the vasoconstriction induced by endothelin-1 in these vascular beds.. The vascular responses of collateral vessels to graded concentrations of somatostatin (10(-9)-10(-5) mol/l), octreotide (10(-10)-10(-6) mol/l), norepinephrine (10(-9)-10(-5) mol/l) and vehicle (Krebs solution) were evaluated in perfused collateral vascular beds of rats with portal hypertension induced by partial portal vein ligation. In addition, the perfusion pressure changes of collateral vessels to endothelin-1 (10(-8) mol/l) in the presence of vehicle(control), somatostatin (10(-6) mol/l) and octreotide (10(-6) mol/l) were tested.. Compared with the vehicle group, norepinephrine significantly increased the perfusion pressure of collateral vessels at concentrations between 10(-7) and 10(-5) mol/l. In contrast, neither somatostatin nor octreotide significantly changed the perfusion pressure. Somatostatin and octreotide significantly enhanced the endothelin-1-induced vasoconstrictive effect on the collaterals.. Somatostatin and octreotide exert no direct vasoconstrictive effect on the collateral vessels of portal hypertensive rats. In the presence of endothelin-1, somatostatin and octreotide exert a local vasoconstrictive effect on these vascular beds.

Topics: Animals; Collateral Circulation; Endothelin-1; Hemostatics; Hypertension, Portal; Male; Octreotide; Portal System; Rats; Rats, Sprague-Dawley; Somatostatin; Vasoconstriction

Hepatic stellate cells (HSC) are involved in the pathogenesis of liver fibrosis; although ET-1 is increased in cirrhosis, its pathophysiological role in fibrogenesis and portal hypertension remains controversial. The aim of this study was to investigate splanchnic hemodynamics and to correlate them with changes in ET-1 expression and HSC activation in bile duct ligated (BDL) rats.. Expression of the ET-1 gene was increased early as measured by quantitative reverse transcriptase-polymerase chain reaction (6-fold 3 days after BDL) whereas ET-1 peptide measured by RIA increased significantly only in the late phase (30-fold at 28 days). There was a linear correlation between portal pressure and the amount of ET-1 in the portal vein (r = 0.66; P = 0.003), as well as between ET-1 and the volume fraction of myofibroblasts (r = 0.80, P < 10(-7)) as assessed by morphometry and immunohistochemical staining using alpha-smooth muscle actin.. During chronic liver injury activation of HSCs and of preproET-1 mRNA is accentuated in the early phase after BDL. The late increase in ET-1 peptide may indicate that this peptide is only secondarily involved in HSC activation. The correlation between ET-1 in portal vein and portal pressure suggests that ET-1 may play an important role in the development of portal hypertension.

Topics: Animals; Aspartic Acid Endopeptidases; Cholestasis; Endothelin-1; Endothelin-Converting Enzymes; Hemodynamics; Hypertension, Portal; Liver; Liver Cirrhosis, Experimental; Male; Metalloendopeptidases; Rats; Rats, Sprague-Dawley; RNA, Messenger

The effect of octreotide on vascular tone in the superior mesenteric artery (SMA) was studied in portal-hypertensive (portal vein-ligated) and sham-operated rats.. In vitro-perfused SMA vascular beds were tested for the cumulative dose-response to octreotide at baseline conditions and after preconstriction with different vasoconstrictors (alpha1-agonist methoxamine, endothelin [ET-1], phorbol ester [PdBu], and potassium chloride [KCl]).. Octreotide did not affect baseline perfusion pressures (without preconstriction). alpha1-Adrenergic-, ET-1-, and PdBu-, but not KCl-, induced vasoconstriction was significantly potentiated by octreotide. This effect was dose-dependent and not different in portal vein-ligated and sham rats. Amplification of alpha1-adrenergic vasoconstriction by octreotide was significantly enhanced by nitric oxide inhibition (N(W)-nitro-L-arginine, 10(-4) mol/L) as well as by removal of the endothelium, and was completely suppressed by inhibition of protein kinase C (calphostin C, 1 micromol/L), phospholipase A2 (quinacrine, 5 micromol/L), and cyclooxygenase (indomethacin, 20 micromol/L).. Not directly, but in the presence of vasoconstrictors involving activation of protein kinase C, octreotide exerts a local vasoconstrictive effect on vascular smooth muscle of SMA. This potentiation is equipotent in portal vein-ligated and sham rats, immediate in onset, and mediated via phospholipase A2 and cyclooxygenase-derived prostanoids. This indicates that in preprandial conditions octreotide enhances the vasoconstrictive effect of dependent vasoconstrictors.

Topics: Adrenergic alpha-Agonists; Animals; Dose-Response Relationship, Drug; Drug Synergism; Endothelin-1; Endothelium, Vascular; Hypertension, Portal; Male; Methoxamine; Nitric Oxide; Octreotide; Phorbol 12,13-Dibutyrate; Protein Kinase C; Rats; Rats, Sprague-Dawley; Reference Values; Vasoconstrictor Agents

Portal hypertension is associated with increased hepatic and collateral resistance to an increased portal blood flow. Endothelin-1 (ET-1) can induce intrahepatic vasoconstriction and consequently increase portal pressure. It is unknown if ET-1 also modulates portal pressure by a direct vasoconstrictive effect on collaterals. This study investigated the collateral vascular responses to ET-1, the receptors in mediation, and the regulation of ET-1 action by nitric oxide and prostaglandin. The portal-systemic collaterals of partially portal vein-ligated rats were tested by in situ perfusion. The concentration-response curves of collaterals to graded concentrations of ET-1 (10(-10)-10(-7) mol/L) with or without BQ-123 (ET(A) receptor antagonist, 2 x 10(-6) mol/L), BQ-788 (ET(B) receptor antagonist, 10(-7) mol/L) or both were recorded. In addition, the collateral responses to ET-1 with preincubation of n(omega)-nitro-L-arginine (NNA; 100 mol/L), indomethacin (INDO; 10 mol/L), or in combination were performed. ET-1 increased the perfusion pressure of collaterals and its effect was significantly suppressed by BQ-123 alone and BQ-123 plus BQ-788, but not BQ-788 alone (P <.05). Incubation with NNA, INDO, or both significantly enhanced the response of collaterals to ET-1 (P < .05). These results show that ET-1 produces a direct vasoconstrictive effect on the collateral vessels of portal hypertensive rats. This effect is mediated by ET(A,) but not ET(B), receptors. Both nitric oxide and prostaglandin modulate the collateral vascular response to ET-1 and may therefore participate in the development and maintenance of portal hypertension.

Topics: Animals; Collateral Circulation; Cyclooxygenase Inhibitors; Drug Combinations; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Portal; Indomethacin; Male; Nitric Oxide; Nitroarginine; Oligopeptides; Peptides, Cyclic; Piperidines; Portal System; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Vasoconstriction

Endothelin-1 has been suggested to play a key role in cirrhotic portal hypertension, but a role of its receptors in vivo is not fully elucidated.. Biliary cirrhosis was induced by bile duct ligation. Expressions of endothelin-1 and its receptors were evaluated by radioimmunoassay and/or reverse-transcription polymerase chain reaction. Hemodynamics were studied using endothelin receptor agonist or antagonist.. Portal pressure and hepatic endothelin-1 concentrations progressively increased in parallel after bile duct ligation. Gene expression of hepatic prepro-endothelin-1 and endothelin B receptor enhanced after bile duct ligation, while that of endothelin A receptor was unchanged. Intraportal administration of endothelin-1 or endothelin B receptor agonist sarafotoxin 6c (0.5 nmol/kg, respectively) progressively raised portal pressure in both sham and cirrhotic rats. Portal hypertensive effect of sarafotoxin 6c was more intense in cirrhotic rats than sham animals. Neither endothelin A receptor antagonist FR139317 (1 mg/kg) nor endothelin B receptor antagonist BQ788 (1 mg/kg) alone ameliorated cirrhotic portal hypertension. Only the combined endothelin A and B blockade was associated with a decrease in portal pressure in cirrhotic rats.. These results indicate that endothelin-1 plays a major role in cirrhotic portal hypertension through endothelin receptor subtype B together with subtype A in vivo.

Topics: Animals; Azepines; Blood Pressure; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Gene Expression; Hemodynamics; Hypertension, Portal; Indoles; Liver; Liver Cirrhosis, Biliary; Oligopeptides; Piperidines; Protein Precursors; Radioimmunoassay; Rats; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA

The aim of this study was to examine if the plasma endothelin-1 (ET-1), a potent vasoconstrictor, level may reflect the severity of portal hypertension associated with liver cirrhosis in biliary atresia (BA).. Forty-eight postoperative BA patients aged 6 months to 20 years were studied. Plasma ET-1 was measured by a sandwich method of enzyme immunoassay. ET-1 was compared with Child's score and laboratory data. ET-1 levels were compared among groups of patients with various degrees of histologic fibrosis and portal hypertension.. Plasma ET-1 was 5.3 +/- 3.5 pg/mL in BA, higher than in controls (3.1 +/- 0.8, n = 27; P <.05). ET-1 correlated with Child's score, serum total bilirubin, direct bilirubin, aspartate aminotransferase, albumin, prothrombin time, hepaplastin test, fibrinogen, cholinesterase, total cholesterol, Fischer's molar ratio, prealubumin, and hyaluronic acid, respectively (P <.05). ET-1 also correlated with the severity of histologic fibrosis, gastroesophageal varices, the presence of splenomegaly, ascites, venous dilatation on the abdominal wall, or pulmonary vascular abnormalities. In 4 patients undergoing liver transplantation (LTx), ET-1 after LTx was lower than that before LTx (P <.05).. Plasma ET-1 level may be a useful index reflecting the severity of cirrhosis and portal hypertension in BA.

Topics: Adolescent; Adult; Biliary Atresia; Biomarkers; Child; Child, Preschool; Endothelin-1; Humans; Hypertension, Portal; Infant; Liver Cirrhosis; Portoenterostomy, Hepatic; Severity of Illness Index

Plasma endothelin-1 (ET-1) levels are increased in patients with cirrhosis and ET-1 production is increased in the liver itself during experimental injury. These data suggest a possible role for this vasoactive peptide in intrahepatic microcirculatory changes that contribute to the pathogenesis of portal hypertension in cirrhosis. Therefore the aims of this study were to determine whether ET-1 levels were abnormal in the livers of patients with cirrhosis and to investigate possible clinical correlates of altered hepatic ET-1 in cirrhosis.. Liver specimens were obtained from explants at the time of liver transplantation in 62 cirrhotic patients; 49 without pretransplantation transjugular intrahepatic portosystemic shunt (TIPS) and 13 with pretransplantation TIPS. The presence of ascites was evaluated by physical examination and ultrasonography. Control specimens consisted of livers with normal morphology obtained from patients who died from nonliver-related causes. Hepatic ET-1 was measured by enzyme immunoassay.. Hepatic ET-1 levels in cirrhotics without (0.17 pg/mg liver tissue) or with TIPS (0.12 pg/mg) were higher than in control patients [0.04 pg/mg (p = 0.02 for ET-1 levels in cirrhotics with or without TIPS vs. control)]. In cirrhotics without ascites who had not had TIPS, ET-1 levels (0.07 pg/mg [0.04-1.00]) were similar to those of the controls. In contrast, ET-1 content was increased in cirrhotics with small (0.11 pg/mg; p = 0.0002) and moderate-to-large (0.69 pg/mg; p = 0.0002) amounts of ascites compared to patients without ascites. There was a modest correlation between ET-1 levels and Child-Pugh score (correlation coefficient 0.32; p = 0.03) and ET-1 levels were significantly higher in patients with Child-Pugh score of 13 or greater (0.88 pg/mg; p = 0.02) than in those with Child-Pugh score of 12 or less (0.16 pg/mg).. Hepatic tissue ET-1 levels are increased in the liver of patients with cirrhosis. This increase appears to be proportional to the severity of both liver disease and ascites. These data raise a possible role for ET-1 in modulation of intrahepatic resistance in cirrhotic portal hypertension.

Topics: Adult; Aged; Ascites; Biomarkers; Chronic Disease; Endothelin-1; Female; Humans; Hypertension, Portal; Liver; Liver Cirrhosis; Liver Transplantation; Male; Middle Aged; Portasystemic Shunt, Transjugular Intrahepatic

Endothelin-1 (ET-1) may be a mediator for portal hypertension in liver cirrhosis. The aim of the present study was to determine the concentrations of ET-1 in the systemic and splanchnic circulation before and after reduction of portal hypertension by transjugular intrahepatic portosystemic shunt implantation (TIPS).. Plasma concentrations of immunoreactive ET-1 were measured in peripheral venous blood samples from 25 patients with liver cirrhosis before and at 1, 3, 9 and 15 months after TIPS. Furthermore, acute effects of TIPS on ET-1 were studied in plasma samples from the hepatic vein, the portal vein 30 minutes before and after TIPS and in the femoral artery (only after TIPS) in a subgroup of 15 patients. In addition, the portocaval pressure gradient was determined before and after TIPS.. Before TIPS peripheral venous plasma ET-1 concentrations (n=25; median 4.2 pg/ml; range 1.9-14.7) were significantly increased in patients with refractory ascites (n=7; median 7.8, range 3.5 14.7) compared to patients with repetitive bleeding (n=18; median 3.4; range 1.9-7.1) (p=0.003). Furthermore, peripheral ET-1 concentrations correlated with the degree of liver dysfunction according to the Child-Pugh classification (Spearman's r=0.46; p=0.02). Following TIPS, peripheral ET-1 concentrations remained unchanged during a follow-up of 15 months. Before TIPS, a positive gradient of ET-1 concentrations from portalvenous to hepatovenous and peripheral venous levels was found (p<0.03). Immediately after TIPS, arterial ET-1 concentrations reached markedly increased levels in individual patients (88, 92 and 103 pg/ml). Severe systemic reactions to these high levels were not observed. Peripheral venous, hepatovenous and portalvenous ET-1 concentrations did not correlate with portocaval pressure gradients.. Cirrhotic patients demonstrated unchanged peripheral venous ET-1 concentrations up to 15 months after TIPS. Portal congestion was associated with increased ET-1 levels in the prehepatic splanchnic area. The effect of portal decompression on splanchnic and systemic ET-1 levels deserves further investigation.

Topics: Adult; Aged; Endothelin-1; Female; Humans; Hypertension, Portal; Liver Cirrhosis; Male; Middle Aged; Portasystemic Shunt, Transjugular Intrahepatic; Prospective Studies; Radioimmunoassay; Splanchnic Circulation

Reduced production of nitric oxide (NO) in the cirrhotic liver results from a defect in hepatic endothelial cell nitric oxide synthase (ecNOS) and appears to contribute to the high intrahepatic resistance and portal hypertension typical of cirrhosis. Therefore, we postulated that targeting a heterologous NOS isoform to sinusoidal endothelial cells or other perisinusoidal cells, such as hepatic stellate cells, would counter the defect in NO production and reduce resistance to blood flow. Recombinant adenovirus (Ad) carrying the neuronal NOS gene (nNOS) targeted liver sinusoidal endothelial cells, stellate cells, and hepatocytes more efficiently than the corresponding cells in cirrhotic livers, but transduction rates were substantial even in cirrhotic animals. Expression of nNOS in each liver cell type, whether from normal or injured liver, caused increased NO production and inhibited endothelin-1-induced contractility of perisinusoidal stellate cells. Finally, in 2 different in vivo models of cirrhosis and portal hypertension, transduction of livers with recombinant Ad.nNOS significantly reduced intrahepatic resistance and portal pressure. The data highlight the feasibility of gene transfer to diseased liver and hepatic cells and demonstrate the potential of a novel therapy for portal hypertension caused by cirrhosis.

Topics: Adenoviridae; Animals; Cell Size; Cells, Cultured; DNA, Complementary; Endothelin-1; Feasibility Studies; Genetic Therapy; Genetic Vectors; Hypertension, Portal; Isoenzymes; Liver Cirrhosis, Experimental; Male; Nerve Tissue Proteins; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitrites; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins

The aim of this study was to determine the role of endothelin (ET)-1 in portal hypertensive gastropathy (PHG) under portal hypertension, in order to investigate whether the ET(A/B) receptor inhibitor improves the permeability of gastric mucosal microvessels in PHG.. Portal hypertensive rats (PVL) and sham-operated rats (CTR) were prepared and then the concentration of plasma ET-1 was measured and the vasopressor response to ET-1 was compared between the two groups. The plasma ET-1 levels in PVL increased significantly compared with CTR; however, the vasopressor response to ET-1 in PVL decreased more than in CTR. Next, the portal venous pressure was measured in both CTR and PVL pretreated with or without a nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), before the injection of ET-1. The portal venous pressure of PVL after receiving ET-1 and being pretreated with L-NAME significantly increased in comparison to the pressure of PVL treated with ET-1 alone (without L-NAME). Moreover, Evans-Blue was injected into each rat and the absorbancy of the gastric contents was measured. The absorbancy of Evans-Blue in PVL increased significantly compared with CTR; however, the absorbancy in PVL+ ET(A/B) receptor inhibitor (Ro47-0203) decreased significantly more than in PVL.. This study showed that ET-1 is a potent vasoconstrictive substance that also has a transitory vasodilative response through NO induced by ET-1 in portal hypertension. In addition, it was found that the vascular permeability of the gastric mucosa increased in portal hypertension and that Ro47-0203 inhibited the hyper-permeability. Accordingly, ET-1 may, thus, play an important role in the development of PHG through NO induced by ET-1. Ro47-0203 may, therefore, be a useful substance for improving PHG in portal hypertension.

Topics: Animals; Bosentan; Capillary Permeability; Endothelin Receptor Antagonists; Endothelin-1; Enzyme Inhibitors; Gastric Mucosa; Hypertension, Portal; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Rats; Rats, Sprague-Dawley; Stomach Diseases; Sulfonamides

Nitric oxide synthase is overexpressed in the portal hypertensive (PHT) esophagus, suggesting that expression of other vasoactive mediatora could also be affected. Therefore, in the present study we determined the expression of endothelin-1 (ET-1) and endothelin receptors, which could contribute to the regulation of the vascular tone in PHT esophagus. In esophageal specimens of PHT and sham operated rats, expression of ET-1 and its receptors A and B (ET(A)R and ET(B)R) mRNAs was studied by reverse transcription-polymerase chain reactions. ET-1 protein expression was assessed by immunostaining and enzyme immunoassay. In PHT esophagus, expression of ET-1, ET(A)R and ET(B)R mRNAs was significantly increased by 2.2-, 2.5- and 1.5-fold, respectively, compared with sham operated. The ET-1 protein was significantly increased by 2.2-fold vs. controls as measured by enzyme immunoassay. ET-1 protein was predominantly localized to endothelia of submucosal veins. Thus, portal hypertension induces over-expression of ET-1 in endothelia of esophageal submucosal vessels. Since ET-1 and its receptors could promote vascular proliferation and induce mucosal damage, the overexpressed ET-1 may play an important role in the development and rupture of esophageal varices in portal hypertension.

Topics: Animals; Endothelin-1; Esophagus; Hypertension, Portal; Mucous Membrane; Portal Vein; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Venous Pressure

This study was aimed to evaluate the source of endothelin-1 (ET-1) in cirrhotic patients. ET-1 is implicated in the pathogenesis of portal hypertension. However, the mechanism and source for increased plasma ET-1 in cirrhotic patients are still obscure. Plasma ET-1 levels in systemic (SV), superior mesenteric (SMV), and splenic venous (SPV) blood were measured in 23 patients with cirrhosis and 8 controls with normal liver. Fourteen removed spleens were immunohistochemically studied for ET-1, CD34, CD68, and CD20. In situ hybridization was done to localize ET-1 messenger RNA (mRNA). In cirrhosis, ET-1 levels in both SMV and SPV were higher than in SV. ET-1 in SV and SPV were significantly higher in cirrhotic patients than in control patients. Three groups of cells in the spleen expressed both protein and mRNA of ET-1: endothelial cells in the sinus, which were also stained for CD34; cells in the germinal center; and cells in the marginal zone of lymphoid sheaths and follicles, which were also stained for CD20 but not for CD34 and CD68. The ET-1 concentration released from the spleen was in parallel with the grade of ET-1 expression in the spleen. The spleen is one of the major sites of ET-1 release in cirrhotic patients. Endothelial cells of the splenic sinus and possibly B lymphocytes in the germinal center and marginal zone of lymphoid sheaths and follicles seem to be the sites of ET-1 production in the spleen.

Topics: Adult; Aged; Aged, 80 and over; Antigens, CD; Antigens, CD34; Antigens, Differentiation, Myelomonocytic; Endothelin-1; Female; Humans; Hypertension, Portal; In Situ Hybridization; Intestinal Mucosa; Liver Cirrhosis; Male; Middle Aged; Portal Vein; Spleen; Venous Pressure

Endothelin 1 induces contraction, proliferation, and collagen synthesis of hepatic stellate cells in vitro, which may be mediated via the endothelin A receptor. It is unknown if specific blockade of the endothelin A receptor inhibits hepatic fibrosis in vivo.. Groups of 10-20 rats with bile duct occlusion were treated with the nonpeptide endothelin-A receptor antagonist LU 135252 at 80 mg. kg(-1). day(-1) from week 1-6 or from week 4-6, or with LU at 10 mg. kg(-1). day(-1) from week 1-6. Animals with bile duct occlusion alone and sham-operated rats without or with LU at 80 mg. kg(-1). day(-1) over 6 weeks served as controls. After 6 weeks, parameters of fibrogenesis were determined.. LU treatment led to improved histology, paralleled by a dose-dependence up to 60% reduction of liver collagen, even when administered at an advanced fibrosis stage. This was accompanied by a decreased messenger RNA of hepatic procollagen alpha1(I) and tissue inhibitor of metalloproteinase 1, 2 major effectors of fibrosis, and of serum procollagen type III, a surrogate marker of liver fibrogenesis.. Selective endothelin-A receptor blockade can dramatically reduce collagen accumulation in rat secondary biliary fibrosis, a model refractory to most potential antifibrotic agents. Endothelin-A receptor antagonists are promising antifibrotic agents in chronic liver disease.

Topics: Administration, Oral; Alanine Transaminase; Alkaline Phosphatase; Animals; Ascites; Aspartate Aminotransferases; Bilirubin; Cholestasis; Collagen; Disease Models, Animal; DNA, Complementary; Endothelin Receptor Antagonists; Endothelin-1; Female; Hydroxyproline; Hypertension, Portal; Jaundice; Liver; Liver Cirrhosis, Experimental; Organ Size; Phenylpropionates; Pyrimidines; Rats; Rats, Wistar; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Tissue Inhibitor of Metalloproteinase-1

Endothelin-1 (ET-1) may mediate increased resistance to hepatic sinusoidal blood flow. We evaluated the hepatic distribution of ET-1 in patients with idiopathic portal hypertension (IPH), in which liver architecture may be normal, and in patients with cirrhosis, in which distortion of hepatic sinusoidal architecture is prominent. Immunohistochemistry and in situ hybridization were used to localize ET-1 in hepatic tissue of patients with IPH and cirrhosis. ET-1 was measured in plasma from a peripheral vein, the hepatic vein, and the portal vein of patients with cirrhosis of the liver and controls. On immunohistochemistry and in situ hybridization, ET-1 was localized to periportal hepatocytes and sinusoidal cells in patients with IPH and cirrhosis. Minimal positive staining for ET-1 was observed in control livers. Plasma ET-1 levels were significantly greater in patients with cirrhosis than in controls. In patients with cirrhosis, ET-1 was greater in the hepatic vein compared with the portal vein. However, the level of plasma ET-1 in patients with cirrhosis did not correlate with either the presence of ascites or portacaval pressure gradient. We conclude that in IPH, ET-1 is localized to sites in which it can modulate intrahepatic resistance. In late stages of cirrhosis, ET-1 may not modulate resistance. We speculate that vascular resistance in late stages of cirrhosis probably results from distortion of hepatic architecture.

Topics: Blood Pressure; Endothelin-1; Humans; Hypertension, Portal; Immunohistochemistry; In Situ Hybridization; Liver; Liver Circulation; Liver Cirrhosis; Portal Vein; Tissue Distribution; Veins; Venae Cavae

Endothelin-1 plays an important role in the regulation of portal hypertension; endothelin antagonists have been extensively studied in portal hypertensive animals. We aimed to evaluate the efficacy of highly selective endothelin antagonists in partial portal vein ligated (PPVL) rats.. Four groups of 7 male Sprague-Dawley rats were administered orally ABT-627 (ET(A)-selective), A-192621 (ET(B)-selective), or A-182086 (non-selective), with the fourth group serving as control. On the 3rd day after beginning treatment animals underwent PPVL. On the 11th day hemodynamics were studied and portal vein ET-1 was measured.. In the control group portal pressure was 13.4+/-SD 0.2 mmHg; this increased to 14.9+/-1.8 (p<0.05) in the ET(B) blocked group. In contrast, ET(A) blockade improved portal hypertension (11.7+/-1.1, p<0.05), while the treatment with the non-selective antagonist had no effect (12.3+/-0.7 n.s.). Mean arterial pressure was not significantly affected by any treatment. Portal vein ET-1 was increased in all groups compared to controls; this increase was limited to the pre-stenotic area (79+/-43 vs 194+/-76 in the pre- and post-stenotic portal vein; p<0.0025).. Oral administration of an ET(A) antagonist ameliorated portal hypertension; we suggest that long-term therapy of portal hypertension with selective ET(A) antagonists may be more beneficial than mixed antagonists.

Topics: Animals; Atrasentan; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Portal; Male; Portal Pressure; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B

Portal hypertension is often accompanied by a hyperdynamic circulation state. Some reports have suggested that nitric oxide (NO) plays an important role in this hyperdynamic state. On the other hand, although endothelin (ET)-1, a powerful vasoconstrictor, was recently identified, little is known about its role in portal hypertension or about the interaction between NO and ET-1. The aim of this study was therefore to investigate whether or not the inhibitor of NO synthase (NOS) might improve portal hypertension, and also to clarify the relationship between NO and ET-1.. Portal hypertensive (PHT) rats, in which hypertension was induced by a two-step ligation of the portal vein (PVL), were used. The mean arterial pressure (MAP), portal pressure (PP), visceral blood flow volume (BFV), and serum levels of NO and ET-1 were determined in PVL rats treated with two NOS inhibitors with different functions: N(G)-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG). Control (CTR) rats. treated by a sham operation (SO), were also studied.. Two-step PVL treatment induced a significant increase in the serum level of NO3-and ET-1 in the portal vein. L-NAME and AG administration significantly decreased PP at doses of 50 mg/kg in PHT rats after 60 min administration, while no inhibitor effected any modification in the CTBR rats. Both NOS inhibitors increased MAP and decreased PP and BFV in the portal vein, gastric mucosa, and spleen, in addition to decreasing the serum levels of NO3- and ET-1 in the PHT rats, while neither blockade modified any parameters in the CTR rats. In PHT rats, L-arginine, a NO substance, reversed the effect of L-NAME, while it did not induce any recovery from the AG effect.. In PHT rats, NO seems to contribute to portal hypertension. PVL increases not only the serum level of NO3-, but also that of ET-1 in the portal vein. Both L-NAME and AG reduce PP and BFV of the portal vein, spleen, gastric mucosa. and liver. In addition, the inhibition of NOS diminishes the serum level not only of NO, but also of ET-1. Use of an appropriate NOS inhibitor may therefore positively affect the hyperdynamic state in portal hypertension.

Topics: Animals; Blood Pressure; Disease Models, Animal; Endothelin-1; Enzyme Inhibitors; Guanidines; Hypertension, Portal; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Portal Vein; Rats; Rats, Sprague-Dawley

Elucidation of the hepatic hemodynamics in acute ethanol administration is an issue of clinical importance for better understanding of alcoholic liver diseases. The purpose of this study is to clarify the mechanism of hepatic microcirculatory disturbances after acute ethanol administration, especially regarding the effects of ethanol on alterations of sinusoidal endothelial fenestrae (SEF) and the involvement of endothelin-1 (ET-1) in the mechanism of portal hypertension induced by ethanol. Ethanol was administrated into the portal vein via the mesenteric vein branch of rats as a continuous infusion (4 and 8 mg/min of ethanol) for 60 min. Hepatic tissue blood flow measured with a laser Doppler blood flowmeter was found to be remarkably decreased with time, whereas portal pressure began to increase at 10 min and showed a significant increase by approximately 1.5 cm H2O at 60 min. Ethanol concentrations in blood at 60 min after 4 and 8 mg/min of ethanol infusion were 0.75 mg/ml and 1.77 mg/ml, respectively. At this point, scanning electron microscopy revealed significant decreases in number and diameter of SEF both in zone 1 and zone 3, with the increase in ethanol level. These findings suggested that decreases in number and diameter of SEF, whether primary or secondary, may lead to the impairment of the transport of plasma substances from sinusoids to hepatocytes in acute ethanol administration. Furthermore, the pretreatment of BQ-123 inhibited a decrease in hepatic tissue blood flow and an increase in portal pressure caused by ethanol, indicating that ET-1 may be involved in the mechanism of hepatic circulatory disturbances in acute ethanol administration.

Topics: Animals; Antihypertensive Agents; Blood Flow Velocity; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Ethanol; Hypertension, Portal; Infusions, Intravenous; Liver; Male; Mesenteric Veins; Microscopy, Electron; Microscopy, Electron, Scanning; Peptides, Cyclic; Portal Vein; Rats; Rats, Wistar; Receptor, Endothelin A; Venous Pressure

Endothelin (ET) is one of the most potent vasoconstrictors known so far. It has been proposed that the ET-induced contraction of hepatic stellate cells (Ito, endothelial cells) is an important mechanism for the development of portal hypertension. The purpose of this study was to investigate in an in vitro model whether ET causes a contraction of the portal vein which can contribute to portal hypertension in cirrhosis. Portal veins from normal and cirrhotic rats were used for experiments. Measurements were performed in vitro for cumulative concentrations of ET-1 and ET-3 (1, 5, 10, 50 and 100 nM). Both ETs caused a dose-dependent increase in portal venous tension; the maximal tension (Tmax) was measured at 50 nM. The measured Tmax was higher for cirrhotic (ET-1: Tmax = 189%; ET-3: Tmax = 175%) than for normal rats (ET-1: Tmax = 130%; ET-3: Tmax = 151%). ET-3 produced a higher tension of portal veins in normal rats than ET-1. In conclusion, this study shows that portal veins from cirrhotic rats react more sensitively to ET than those from normal rats. Besides the ET-induced contraction of hepatic stellate cells, contraction of the portal vein and its intrahepatic branches, especially in cirrhotic individuals, has to be considered as a further mechanism of ET contributing to portal hypertension.

Topics: Animals; Carbon Tetrachloride; Dose-Response Relationship, Drug; Endothelin-1; Endothelin-3; Hypertension, Portal; In Vitro Techniques; Liver Cirrhosis, Experimental; Male; Muscle Contraction; Portal Vein; Rats; Rats, Sprague-Dawley

Factors that increase resistance to blood flow through the hepatic sinusoids when portal hypertension occurs in the absence of significant hepatic fibrosis are not completely understood. Experiments were designed to test the hypothesis that endothelin-1 (ET-1) is one of the humoral factors that increases sinusoidal vascular resistance in a bile duct- ligated noncirrhotic portal hypertensive (BDL) rat. The effect of ET-1 and nitric oxide (NO) on contractility of rings of portal vein taken from BDL rats was tested. The effect of ET-1 and NO on intrahepatic resistance in an isolated perfused liver was studied, and localization of ET-1 in the liver was identified by immunohistochemistry. Portal vein rings in BDL rats showed increased maximal tension in response to ET-1, as well as a shift of the dose-response curve to the left as compared with sham-operated animals. Removal of the endothelium further increased contractility. In isolated perfused liver studies, ET-1 increased portal resistance in both sham operated and BDL rats. The endothelin Type A receptor antagonist BQ 123 lowered the high portal resistance in BDL rats to levels comparable with sham operated animals. Infusion of L-arginine lowered resistance to a much smaller extent. In livers from BDL rats, ET-1 was localized in periportal and pericentral hepatocytes and hepatic sinusoidal cells. We conclude that in a BDL model of portal hypertension where distortion of hepatic architecture by fibrosis is minimal, increased resistance to portal blood flow may be mediated by ET-1.

Topics: Animals; Arginine; Endothelin-1; Hypertension, Portal; In Vitro Techniques; Male; Nitric Oxide; omega-N-Methylarginine; Peptides, Cyclic; Perfusion; Rats; Rats, Inbred F344; Vascular Resistance; Vasoconstriction

Topics: Animals; Bile Ducts; Endothelin-1; Hepatopulmonary Syndrome; Homeostasis; Hypertension, Portal; Ligation; Lung; Pulmonary Circulation; Rats

Biliary cirrhosis in the rat triggers intrapulmonary vasodilatation and gas exchange abnormalities that characterize the hepatopulmonary syndrome. This vasodilatation correlates with increased levels of pulmonary microcirculatory endothelial nitric oxide synthase (eNOS) and hepatic and plasma endothelin-1 (ET-1). Prehepatic portal hypertension induced by portal vein ligation (PVL) does not cause similar changes, suggesting that ET-1 in cirrhosis may modulate pulmonary eNOS and vascular tone. We assessed whether ET-1 altered eNOS expression and nitric oxide production in bovine pulmonary artery endothelial cells (BPAECs) and if a 2-wk low-level intravenous ET-1 infusion in PVL animals modulated pulmonary eNOS levels, microcirculatory tone, and gas exchange. ET-1 caused a 2.5-fold increase in eNOS protein in BPAECs, inhibitable with an endothelin B receptor antagonist, and an increase in eNOS mRNA and nitrite production. ET-1 infusion in PVL animals caused increased pulmonary eNOS levels, intrapulmonary vasodilatation, and gas exchange abnormalities without increasing pulmonary arterial pressure. ET-1 produced during hepatic injury may contribute to the hepatopulmonary syndrome by modulating eNOS and inducing pulmonary microcicrulatory vasodilatation.

Topics: Animals; Blotting, Western; Cattle; Cell Division; Cells, Cultured; Disease Models, Animal; Endothelin-1; Endothelium, Vascular; Gene Expression Regulation, Enzymologic; Hepatopulmonary Syndrome; Hypertension, Portal; Injections, Intravenous; Liver; Liver Cirrhosis, Experimental; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Pulmonary Artery; Pulmonary Circulation; Pulmonary Gas Exchange; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Vasodilation

By using a selective ROCK inhibitor Y-27632, the role of Rho-ROCK signaling in the function of hepatic stellate cells in culture was studied. Stellate cells maintained the "star-like" configuration of the quiescent stage in the presence of Y-27632, while the expression of smooth muscle alpha-actin and PDGF receptor beta was not affected by the agent. Serum-stimulated migration of the cells was significantly suppressed by Y-27632. The contraction of stellate cells induced by 5 nM endothelin-1 was attenuated by the agent in a dose-dependent manner. Formation of F-actin stress fibers and phosphorylation of myosin light chain was apparently reduced by Y-27632 even under the stimulation with endothelin-1. On the other hand, ex vivo liver perfusion experiment revealed that endothelin-1 (2 nM)-induced increase of portal vein constriction was almost completely inhibited by 20 microM Y-27632 with a concomitant improvement of hepatocyte degeneration. These results suggest that ROCK is one of the key regulators of stellate cell motility and that the clinical application of ROCK inhibitors such as Y-27632 should be considered in the reduction of portal hypertension in liver fibrosis and cirrhosis.

Topics: Actins; Amides; Animals; Antihypertensive Agents; Cell Movement; Cell Size; Cells, Cultured; Endothelin-1; Enzyme Inhibitors; Hypertension, Portal; Intracellular Signaling Peptides and Proteins; Liver; Male; Myosin Light Chains; Phosphorylation; Portal Vein; Protein Serine-Threonine Kinases; Pyridines; Rats; Rats, Wistar; rho-Associated Kinases

To investigate the level of plasma calcitonin gene related peptide (CGRP) and endothelin-1 (ET-1) to assess their role on portal hypertension formation and progression and liver function injury in liver cirrhosis and the possible relation between them.. CGRP and ET-1 were measured in plasma samples collected from 24 healthy controls and 61 liver cirrhosis patients.. Plasma CGRP and ET-1 level were significantly higher in cirrhotic patients than those in healthy controls. Comparisons of the levels of plasma CGRP and ET-1 in group of patients with different liver function were shown as follows: Child C > Child B > Child A. An analysis among the groups showed that plasma CGRP and ET-1 were markedly higher in the groups with esophageal varices accompanied by severe or moderate ascites (LC(4)) and with simple severe or moderate ascites (LC(3)) than in the groups with esophageal varices accompanied by mild or no ascites (LC(2)). The levels were also significantly higher in group LC(2) than those in group without varices and ascites (LC(1)). No statistical difference of plasma CGRP and ET-1 levels was found between group LC(1) or Child A and normal controls. There was positive correlation between plasma CGRP and ET-1. The increased concentration of both of them correlated negatively with the declined level of plasma albumin.. The increase of plasma CGRP and ET-1 is closely associated with the severity of liver cirrhosis and the formation and progression of portal hypertension. The disturbance of the balance between plasma CGRP and ET-1 may contribute to the pathologic process of liver injury.

Topics: Adult; Ascites; Calcitonin Gene-Related Peptide; Endothelin-1; Esophageal and Gastric Varices; Female; Humans; Hypertension, Portal; Liver Cirrhosis; Male; Middle Aged; Radioimmunoassay

Intraportal infusion of endothelin-1 (ET-1), a potent vasoconstrictor, significantly elevates portal venous pressure. To determine the major site of vascular constriction in the intrahepatic porto-sinusoidal system, we performed an in situ perfusion of rat livers with 1 nmol/L ET-1 at a flow rate of 20 mL/min. Portal pressure rose from 22 cm H2O to 54 cm H2O within 25 minutes. Specimens were prepared for light-microscopic serial reconstruction and electron microscopy. The distal segment of preterminal portal venules (DS/PPV) with an inner diameter of 40 to 80 microm showed complete obliteration of the lumen over a 300-microm distance caused by the intense contraction of perivascular smooth muscle cells and protruding of endothelial cells into the lumen. The proximal segment of preterminal portal venules (PS/PPV) with a larger diameter up to 150 microm also underwent strong constriction, but still had luminal space for the flow, while the PS/PPV with a diameter of 150 to 400 microm showed moderate or mild constriction and retained a wide lumen. Neither terminal portal venules, inlet venules, sinusoids, nor central veins, however, exhibited demonstrable constriction. Liver parenchyma fed by the inlet venules that emerged from the PS/PPV exhibited a wide sinusoidal lumen and vacuolated hepatocytes caused by the influx of excess portal perfusate that escaped from the occlusive areas. The present study has revealed that the DS/PPV functions as a presinusoidal quasi-sphincter mechanism and is involved in the redistribution of intrahepatic portal flow under increased portal pressure.

Topics: Animals; Endothelin-1; Endothelium, Vascular; Hypertension, Portal; Male; Microscopy, Electron; Portal Pressure; Portal Vein; Rats; Rats, Wistar; Vasoconstriction

Hepatic levels of a powerful vasoconstrictor endothelin-1 (ET-1) and its receptors increase in human and carbon tetrachloride (CCl4)-induced liver cirrhosis. The aim of this study was to determine whether antagonism of hepatic ET-1 receptors ameliorates CCl4-induced hepatic injury and portal hypertension in rats. Acute liver injury was induced by a single intraperitoneal injection of CCl4 (0.3 ml/kg), whereas cirrhosis and portal hypertension were induced by CCl4 treatment (0.15 ml/kg twice a week) for 8 weeks. Hepatic morphology, ET-1 and its receptors, and portal venous pressures were determined. Increases in ET-1 and its receptors occurred within 24 h of CCl4 administration, and progressively thereafter during the development of cirrhosis. The acute CCl4-induced hepatic injury was characterized by significant increases in portal pressure (from 8.7+/-1.8 to 17.6+/-3.3 mmHg; p<0.01) and serum levels of liver enzymes, as well as massive hepatocellular necrosis (62+/-8%). Intravenous administration of an ET-1 receptor antagonist TAK-044 reduced portal pressure to 13.6+/-2.8 mmHg (p<0.05), and ameliorated hepatocellular necrosis by about 35% (p<0.001). TAK-044 treatment also produced significant reduction in serum levels of liver enzymes. In cirrhotic rats, portal venous infusion of TAK-044 reduced portal hypertension by about 40% (p<0.05). In conclusion, these results indicate involvement of ET-1 in acute liver injury as well as portal hypertension associated with hepatic cirrhosis, and a potential for ET-1 receptor antagonists in the treatment of these pathologic conditions.

Topics: Animals; Carbon Tetrachloride; Cells, Cultured; Endothelin Receptor Antagonists; Endothelin-1; Hypertension, Portal; Liver; Liver Cirrhosis, Experimental; Male; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptors, Endothelin

Portal hypertension (PHT) is characterized by increased portal pressure caused in part by a reduction in mesenteric vascular resistance. The aim of this study was to evaluate the role of endothelin (ET) and specific ET receptors in maintaining the vasculopathy of PHT. PHT was created in Sprague-Dawley rats by a partial portal vein ligation. Control animals were sham-operated. ET receptor expression was determined in the superior mesenteric artery of sham and PHT rats by in situ autoradiography, radioligand binding analysis, and reverse-transcription polymerase chain reactions (RT-PCR). The pressor response to ET-1 was determined in vitro using isolated vascular rings and in vivo by measuring mean arterial pressure, splanchnic blood flow, and portal venous pressure following treatment with ET and selective ET receptor antagonists. The pressor response to ET in vitro was significantly enhanced in PHT concomitant with increased ET-A and ET-B receptor expression. There was a significant increase in the peak pressor response to ET (10 microg/kg intravenously) in portal hypertensive rats without any significant change in plasma ET-1 levels. There was no significant difference in the peak splanchnic blood flow or portal venous pressure response following ET-A receptor blockade with JKC-301 infusion (200 microg/kg intravenously). In contrast, ET-B receptor blockade with IRL-1038 (200 microg/kg intravenously) preferentially decreased splanchnic blood flow and portal venous pressure in portal hypertensive rats. These data suggest that enhanced ET-B receptor expression in portal hypertensive vessels contributes to the maintenance of elevated portal pressure in these animals.

Topics: Animals; Blood Vessels; Endothelin-1; Hemodynamics; Hypertension, Portal; Male; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Splanchnic Circulation; Vasoconstriction

In patients with cirrhosis, the plasma level of endothelin, a potent vasoconstrictor peptide, is elevated, and endothelin plays a role in increased intrahepatic vascular resistance. Thus, the aim of this study was to evaluate the hemodynamic effects of bosentan, a mixed ET(A) and ET(B) endothelin receptor antagonist in three models of portal hypertension. In all groups of rats, endothelin (2 microg/kg intravenously) administration significantly increased intrahepatic vascular resistance. In rats with secondary biliary cirrhosis, bosentan (30 mg/kg) significantly reduced portal pressure from 14.6 +/- 1.2 to 12.1 +/- 0.6 mm Hg, while portal blood flow and cardiac output increased by 45% and 57%, respectively. Thus, hepatocollateral vascular resistance decreased significantly from 177 +/- 19 to 101 +/- 9 dyn x s x cm(-5) x 10(-3). Similar results were observed in rats with CCl4-induced cirrhosis. In isolated perfused cirrhotic rat livers, bosentan (1 to 100 micromol/L) had no significant effect on hepatic vascular resistance. In portal vein-stenosed rats, bosentan administration significantly decreased portal pressure from 13.1 +/- 0.6 to 11.4 +/- 0.5 mm Hg by reducing portosystemic vascular resistance, because bosentan had no effect on vascular resistance of normal rat liver. In conclusion, bosentan administration decreased portal pressure in vivo by reducing hepatocollateral vascular resistance in rats with cirrhosis. Thus, mixed endothelin receptor antagonists might be a new approach in the pharmacological treatment of portal hypertension.

Topics: Animals; Antihypertensive Agents; Bosentan; Endothelin Receptor Antagonists; Endothelin-1; Hemodynamics; Hypertension, Portal; Liver Cirrhosis, Experimental; Male; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptor, Endothelin B; Sulfonamides

To investigate expression of endothelin-1 (ET-1) and nitric oxide synthase(NOS) gene in gastric mucosa in the rats with cirrhosis and portal hypertensive gastropathy (PHG) after disconnective operation.. Wistar rats were divided into three groups: normal (n = 12), cirrhosis and PHG (n = 12), and post-disconnective (n = 12). The rat models were induced by intraperitonal injection of thiocetamide for 16 weeks. The third group rats were reared for 3 months after the operations. ET-1 and NOS mRNA from the gastric mucosa of the three groups were measured quantitatively by Dot blot technique.. ET-1 mRNA decreased in the PHG rats as compared to the nomal rats (P < 0.01). Further decrease was found in the post-disconnective rats (P < 0.01). NOS mRNA increased slightly in the PHG rats (P > 0.05) and increased obviously in the post-disconnective rats (P < 0.01).. After the cirrhosis and PHG rats were subjected to disconnective operations, ET-1 was insufficient and NOS was too much in the gastric mucosa. These resulted in the gastric mucosal vessel dilatation. The imbalance of ET/NO proportion could partly attribute to rebleeding after disconnection.

Topics: Animals; Endothelin-1; Gastric Mucosa; Hypertension, Portal; Liver Cirrhosis, Experimental; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Portasystemic Shunt, Surgical; Postoperative Period; Random Allocation; Rats; Rats, Wistar; RNA, Messenger

A porcine model of endotoxemic shock was used to test the hypothesis that endothelins (ET) mediate the sustained increases in portal and pulmonary vascular resistances. Anesthetized pigs (n = 18) were instrumented and pretreated with 1) saline as a control; 2) indomethacin (Idm), a cyclooxygenase (Cox) inhibitor; or 3) Idm + bosentan (Bos), a mixed ET-receptor antagonist, and then were treated with endotoxin to produce shock and followed for 240 min. Global and regional hemodynamic parameters and plasma levels of ET-1 and thromboxane B2 were measured. The results show that 1) ET is independently responsible for the sustained increase in pulmonary vascular resistance; 2) ET and Cox products combine to increase portal venous resistance; 3) ET independently reduces cardiac output and attenuates or negates global systemic arterial vasodilation (presumptively mediated by nitric oxide) and exhibits regional differences, having little if any influence on the gut arterial bed. When considered with our prior study of nitric oxide regulation of the same beds in endotoxemic shock (N. Brienza, T. Ayuse, J. P. Revelly, C. P. O'Donnell, and J. L. Robotham, J. Appl. Physiol. 78: 784-792, 1995), the similarities between the portal venous and pulmonary arterial beds suggest that these two beds reflect phenomena occurring in microvascular and/or venous beds in multiple organs. The overall results suggest that a dynamic balance exists between NO and ET regulating arterial and microvascular and/or venous vasomotor activity during the evolution of endotoxemic shock.

Topics: Analysis of Variance; Animals; Bosentan; Cyclooxygenase Inhibitors; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Endotoxemia; Hemodynamics; Hypertension, Portal; Hypertension, Pulmonary; Indomethacin; Liver Circulation; Portal System; Pulmonary Artery; Pulmonary Circulation; Regional Blood Flow; Shock, Septic; Sulfonamides; Swine; Thromboxane B2; Vascular Resistance

Isolated, perfused rat liver preparations (IPRL), obtained from rats with carbon tetrachloride-induced cirrhosis and normal controls, were used to investigate responses to the vasoactive peptide endothelin-1 (ET-1). The mean perfusion resistance (R) of cirrhotic IPRL was significantly greater than that of controls (2.63 +/- 0.24 vs 1.54 +/- 0.14 mmHg/mL per min per g; P < 0.01). Both control and cirrhotic IPRL demonstrated a concentration-related increase in resistance (delta R) in response to ET-1, with a minimum effective concentration of approximately 3 x 10(-11) mol/L. The EC50 (-log of the 50% effective concentration) was not significantly different between cirrhotic and control IPRL (8.48 +/- 0.19 and 8.79 +/- 0.11, respectively); however, the maximum response to ET-1 was significantly greater in cirrhotic preparations (R: 10.4 +/- 2.2 vs 4.4 +/- 0.5 mmHg/mL per min per g, P < 0.01; DR, 7.8 +/- 2.1 vs 2.8 +/- 0.4 mmHg/mL per min per g, P < 0.01). Following maximal stimulation by ET-1, the mean portal-hepatic venous pressure gradient at a physiological flow rate of 1 mL/min per g was approximately 90% greater across cirrhotic IPRL than that across normal IPRL (11.2 +/- 2.0 vs 5.9 +/- 0.9 mmHg, respectively; P < 0.05). These results support the hypothesis that endogenously released ET-1 has a significant influence on the portal vascular resistance of cirrhotic liver in vivo and has an important role in the pathogenesis of portal hypertension.

Topics: Animals; Carbon Tetrachloride Poisoning; Endothelin-1; Hypertension, Portal; Liver; Liver Circulation; Liver Cirrhosis, Experimental; Male; Perfusion; Portal Pressure; Portal Vein; Rats; Rats, Wistar; Vasoconstriction

1. Increased production of nitric oxide (NO) has been suggested to underlie both the vascular hyporeactivity to vasoconstrictors and the splanchnic vasodilatation seen in portal hypertension. This study assessed the role of NO in the vasoconstrictor hyporeactivity of portal vein-ligated (PVL) rats in isolated and in situ perfused mesenteric arterial beds. 2. Isolated perfused mesenteric arteries of PVL rats were significantly less reactive to noradrenaline (NA), methoxamine (METH), arginine vasopressin (AVP) and endothelin-1 (ET-1) than those from sham-operated (Sham) rats. 3. Blockade of NO synthesis with NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) in isolated perfused mesenteric arteries from PVL rats restored the reactivity to bolus injections of AVP and ET-1, but had little effect on the hyporeactivity to NA or METH. Cyclo-oxygenase inhibition with indomethacin (5 microM) likewise did not restore reactivity to METH of isolated perfused mesenteric arteries of PVL rats. 4. The hyporeactivity to METH seen in isolated perfused mesenteric arteries from PVL rats was reduced by low concentrations of AVP (20 nM) or ET-1 (1 nM) which per se caused only a slight increase in perfusion pressure. When L-NAME (100 microM) was combined with AVP (20 nM) or ET-1 (1 nM), respectively, reactivity to METH of isolated perfused mesenteric arteries of PVL rats was restored to the level seen in Sham rats. These effects of AVP and ET-1 were not mimicked by precontracting the vessels with 5-hydroxytryptamine (5 microM). 5. The differential effects of L-NAME and AVP on the hyporesponsiveness to methoxamine and AVP were corroborated by experiments performed with the in situ perfused mesenteric vascular bed preparation. 6. These data indicate that both NO-dependent and NO-dependent mechanisms are involved in the vasoconstrictor hyporesponsiveness of mesenteric arteries from portal hypertensive rats. The hyporeactivity to AVP and ET-1 is mediated by NO whereas the reduced responsiveness to adrenoceptor agonists appears to be predominantly NO-independent AVP and ET-1, in addition, seem to inhibit the NO-independent mechanism of vascular hyporeactivity, since the hyporesponsiveness to METH was reduced in the presence of AVP or ET-1 and abolished by the combination of these peptides with L-NAME.

Topics: Animals; Arginine Vasopressin; Blood Pressure; Endothelin-1; Enzyme Inhibitors; Hemodynamics; Hypertension, Portal; In Vitro Techniques; Male; Mesenteric Arteries; Methoxamine; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Vasoconstrictor Agents; Vasodilator Agents

Portal hypertension predisposes gastric mucosa to increased injury by various noxious factors. Because endothelin-1 (ET-1) is a potent vasoconstrictor that enhances gastric mucosal injury, we examined ET-1 expression in the portal hypertensive (PHT) gastric mucosa and its possible role in increased mucosal susceptibility to damage.. In gastric specimens of PHT or sham-operated rats, ET-1 mRNA expression was studied by S1-nuclease protection assay and ET-1 protein by enzyme immunoassay and immunostaining. We also determined the extent of ethanol-induced gastric mucosal necrosis in PHT and sham-operated rats after administering either a placebo or FR 139317, a selective ETA receptor antagonist.. In PHT stomachs ET-1 mRNA expression and protein concentration were significantly increased compared with sham-operated controls: mRNA expression (ET-1/glyceraldehyde-3-phosphate-dehydrogenase ratio), 0.54 +/- 0.18 versus 0.30 +/- 0.08; protein concentration, 7.36 +/- 2.21 pg/mg versus 3.93 +/- 0.40 pg/mg, respectively; both p < 0.01. Immunofluorescence signal of ET-1 protein was predominantly localized to endothelia of gastric mucosal and submucosal vessels. In PHT stomachs FR 139317 significantly reduced mucosal necrosis (percentage of necrotic area, from 24.9 +/- 5.9% to 10.8 +/- 4.0%; p < 0.01), although it had no effect on sham-operated controls.. Portal hypertension activates the ET-1 gene with overexpression of ET-1 protein in the gastric mucosa. Protection of PHT gastric mucosa by ETA receptor antagonist against damage indicates that overexpression of ET-1 plays an important role in increased susceptibility of PHT gastric mucosa to injury.

Topics: Animals; Azepines; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Ethanol; Gastric Mucosa; Glyceraldehyde-3-Phosphate Dehydrogenases; Hemodynamics; Hypertension, Portal; Indoles; Necrosis; Protein Biosynthesis; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; RNA, Messenger; Transcription, Genetic; Veins; Venules

Vasoactive substances may have a role in the pathogenesis of functional renal abnormalities in patients with cirrhosis. We determined renal vasoactive mediators in rats with portal hypertension since the balance in each part of the kidney between the vasodilator activity of prostaglandin E2 and the vasospastic activity of thromboxane A2, leukotriene B4, leukotriene C4, endothelin-1 and platelet activating factor may determine renal function. Rats with partial portal vein ligation (n = 7), complete bile duct ligation (n = 6) and sham operated (n = 10) were studied. Three weeks following surgery renal function tests, including fractional excretion of sodium [Fe(Na)] were measured. Rats were anesthetized, splenic pulp pressure was measured, kidneys were removed, and cortex, medulla and papilla were separated and homogenized for determination of prostaglandin E2, thromboxane B2, leukotriene B4, leukotriene C4 and endothelin-1 by radioimmunoassay (ng/g) and platelet activating factor activity (pg/10 mg) by platelet aggregation.. Pulp pressure was > 13 mmHg in portal vein ligated and bile duct ligated and 6 mmHg in sham operated rats. In bile duct ligated rats there was a 70% decrease in Fe(Na) and a significant decrease in cortical and papillary prostaglandin E2, whereas cortical thromboxane B2 and platelet activating factor activity in the cortex, medulla and papilla were double that of sham operated rats. A similar but insignificant trend of changes was found in portal vein ligated rats. Medullary leukotriene B4 was significantly decreased in bile duct ligated rats. Papillary leukotriene B4 was not detected in bile duct ligated and portal vein ligated rats. Renal leukotriene C4 generation in the three groups was either unchanged (papilla) or beyond detection (cortex and medulla). Medullary and papillary endothelin-1 in portal vein ligated and bile duct ligated rats were 178%-130% higher than in sham operated rats. A significant negative correlation was found between Fe(Na) and cortical and medullary thromboxane B2 generation and medullary platelet activating factor activity.. 1) In bile duct ligated rats enhanced intrarenal generation of thromboxane A2 and platelet activating factor may contribute to decreased renal sodium excretion. 2) The role of decreased intrarenal prostaglandin E2 and increased intrarenal endothelin-1 content in bile duct ligated rats is not yet understood. 3) Renal leukotriene generation is either decreased or undetected in portal vein ligated and bile duct ligated rats.

Topics: Animals; Bile Ducts; Eicosanoids; Endothelin-1; Hemodynamics; Hypertension, Portal; Kidney; Kidney Function Tests; Ligation; Male; Platelet Activating Factor; Rats; Rats, Sprague-Dawley; Renal Circulation

Rats with portal hypertension and experimental liver disease may exhibit increased susceptibility of the gastric mucosa to damage by noxious agents, and increased bacterial translocation through the bowel wall. The aim of this study was to determine mucosal gastric and colonic generation of vasoactive substances, because they may contribute to the altered mucosal function. Rats with partial vein ligation (n = 7), complete bile duct ligation (n = 6) and sham-operated rats (n = 10) were studied. Three weeks following surgery rats were anesthetized, splenic pulp pressure was measured, stomachs and colons were removed and mucosa was extracted for determination of prostaglandin E2, thromboxane B2, leukotriene B4, leukotriene C4 and endothelin-1 by radioimmunoassay (ng/g) and platelet activating factor activity (pg/10 mg) by platelet aggregation. Pulp pressure was > 13 mmHg in partial vein ligated rats and bile duct ligated rats and 6 mmHg in sham-operated rats. No macroscopic or microscopic lesions were seen any of the removed tissues. Gastric mucosal prostaglandin E2 and thromboxane B2 generation were decreased by 35% and 7%, respectively, in bile duct ligated rats (bile duct ligated versus sham-operated, p < 0.05 for prostaglandin E2 and thromboxane B2). Gastric leukotriene B4 and C4 generation, platelet activating factor activity and endothelin-1 content did not differ significantly among the three groups. A different pattern of changes was observed in the colon. Colonic leukotriene B4 generation and endothelin-1 content were increased in bile duct ligated rats by 105% and 210%, respectively (bile duct ligated versus sham-operated, p < 0.05 for leukotriene B4 and endothelin-1). The decreased gastric mucosal prostaglandin E2 generation of bile duct ligated rats may render the gut mucosa of these animals relatively ischemic and vulnerable to damage by noxious agents. The increased colonic leukotriene B4 generation and the increased endothelin-1 content of the colonic mucosa of bile duct ligated rats may promote inflammatory and ischemic changes in the colonic mucosa and may enable bacterial translocation.

Topics: Animals; Bile Ducts; Colon; Eicosanoids; Endothelin-1; Gastric Mucosa; Hemodynamics; Hypertension, Portal; Intestinal Mucosa; Ligation; Liver Diseases; Male; Platelet Activating Factor; Portal Vein; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Stomach

The present study evaluates the effects of pre-hepatic portal hypertension, induced in rats by partial portal vein ligation, on the responsiveness of rostral (proximal) and caudal (distal) rings from the mesenteric vein. The anatomical origin of the sample influenced the response to vasoconstrictors in sham-operated animals, and this pattern of reactivity was specifically modified in portal-ligated rats. In veins from sham-operated rats, contraction induced by a submaximal concentration of KCl (60 mM) was greater in proximal than in distal rings. Vasopressin and 5-hydroxytryptamine contracted mainly distal rings, methoxamine showed a greater effect on proximal rings, and endothelin-1 and angiotensin-II contracted vein rings independently of their anatomical origin. In veins from portal hypertensive rats, response to KCl (60 mM) were increased in distal rings, and all rings exhibited enhanced reactivity to vasopressin and 5-hydroxyptyptamine as well as attenuation of the response to methoxamine. Responses to endothelin-1 were decreased in proximal vein rings from portal hypertensive rats whereas responses to angiotensin-II were not influenced by the anatomical origin. Incubation with atropine, propranolol or indomethacin, did not modify the responses to vasopressin and 5-hydroxytryptamine in tissues from either sham-operated or portal hypertensive animals. Likewise, the hyporeactivity to methoxamine and endothelin-1 in rings from portal hypertensive rats persisted in the presence of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester. These results suggest the physiological existence of anatomical differences in the responsiveness to vasoconstrictors throughout the mesenteric vein and that changes in the responsiveness of the mesenteric vein induced by portal hypertension are specific for each agonist and possibly result from individual variations at a receptor or post-receptor level.

Topics: Animals; Endothelin-1; Hypertension, Portal; Iliac Vein; In Vitro Techniques; Male; Mesenteric Veins; Muscle, Smooth, Vascular; Potassium Chloride; Rats; Rats, Sprague-Dawley; Vasoconstrictor Agents; Vasopressins