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Granger DN, Holm L, Kvietys P. The Gastrointestinal Circulation: Physiology and Pathophysiology. Compr Physiol 2016; 5:1541-83. [PMID: 26140727 DOI: 10.1002/cphy.c150007] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The gastrointestinal (GI) circulation receives a large fraction of cardiac output and this increases following ingestion of a meal. While blood flow regulation is not the intense phenomenon noted in other vascular beds, the combined responses of blood flow, and capillary oxygen exchange help ensure a level of tissue oxygenation that is commensurate with organ metabolism and function. This is evidenced in the vascular responses of the stomach to increased acid production and in intestine during periods of enhanced nutrient absorption. Complimenting the metabolic vasoregulation is a strong myogenic response that contributes to basal vascular tone and to the responses elicited by changes in intravascular pressure. The GI circulation also contributes to a mucosal defense mechanism that protects against excessive damage to the epithelial lining following ingestion of toxins and/or noxious agents. Profound reductions in GI blood flow are evidenced in certain physiological (strenuous exercise) and pathological (hemorrhage) conditions, while some disease states (e.g., chronic portal hypertension) are associated with a hyperdynamic circulation. The sacrificial nature of GI blood flow is essential for ensuring adequate perfusion of vital organs during periods of whole body stress. The restoration of blood flow (reperfusion) to GI organs following ischemia elicits an exaggerated tissue injury response that reflects the potential of this organ system to generate reactive oxygen species and to mount an inflammatory response. Human and animal studies of inflammatory bowel disease have also revealed a contribution of the vasculature to the initiation and perpetuation of the tissue inflammation and associated injury response.
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Affiliation(s)
- D Neil Granger
- Department of Molecular and Cellular Physiology, LSU Health Science Center-Shreveport, Shreveport, Louisiana, USA
| | - Lena Holm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Peter Kvietys
- Department of Physiological Sciences, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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Sacerdoti D, Pesce P, Di Pascoli M, Brocco S, Cecchetto L, Bolognesi M. Arachidonic acid metabolites and endothelial dysfunction of portal hypertension. Prostaglandins Other Lipid Mediat 2015; 120:80-90. [PMID: 26072731 DOI: 10.1016/j.prostaglandins.2015.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 12/12/2022]
Abstract
Increased resistance to portal flow and increased portal inflow due to mesenteric vasodilatation represent the main factors causing portal hypertension in cirrhosis. Endothelial cell dysfunction, defined as an imbalance between the synthesis, release, and effect of endothelial mediators of vascular tone, inflammation, thrombosis, and angiogenesis, plays a major role in the increase of resistance in portal circulation, in the decrease in the mesenteric one, in the development of collateral circulation. Reduced response to vasodilators in liver sinusoids and increased response in the mesenteric arterioles, and, viceversa, increased response to vasoconstrictors in the portal-sinusoidal circulation and decreased response in the mesenteric arterioles are also relevant to the pathophysiology of portal hypertension. Arachidonic acid (AA) metabolites through the three pathways, cyclooxygenase (COX), lipoxygenase, and cytochrome P450 monooxygenase and epoxygenase, are involved in endothelial dysfunction of portal hypertension. Increased thromboxane-A2 production by liver sinusoidal endothelial cells (LSECs) via increased COX-1 activity/expression, increased leukotriens, increased epoxyeicosatrienoic acids (EETs) (dilators of the peripheral arterial circulation, but vasoconstrictors of the portal-sinusoidal circulation), represent a major component in the increased portal resistance, in the decreased portal response to vasodilators and in the hyper-response to vasoconstrictors. Increased prostacyclin (PGI2) via COX-1 and COX-2 overexpression, and increased EETs/heme-oxygenase-1/K channels/gap junctions (endothelial derived hyperpolarizing factor system) play a major role in mesenteric vasodilatation, hyporeactivity to vasoconstrictors, and hyper-response to vasodilators. EETs, mediators of liver regeneration after hepatectomy and of angiogenesis, may play a role in the development of regenerative nodules and collateral circulation, through stimulation of vascular endothelial growth factor (VEGF) inside the liver and in the portal circulation. Pharmacological manipulation of AA metabolites may be beneficial for cirrhotic portal hypertension.
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Affiliation(s)
- David Sacerdoti
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy.
| | - Paola Pesce
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Marco Di Pascoli
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Silvia Brocco
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Lara Cecchetto
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
| | - Massimo Bolognesi
- Department of Medicine, University of Padova Via Giustiniani, 2, 35100 Padova, Italy
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Uehara H, Akahoshi T, Kawanaka H, Hashimoto N, Nagao Y, Tomikawa M, Taketomi A, Shirabe K, Hashizume M, Maehara Y. Endothelin-1 derived from spleen-activated Rho-kinase pathway in rats with secondary biliary cirrhosis. Hepatol Res 2012; 42:1039-47. [PMID: 22594838 DOI: 10.1111/j.1872-034x.2012.01021.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Splenectomy or partial splenic embolism has been reported to improve liver function in patients with hypersplenism and liver dysfunction. The aim of this study was to investigate the mechanism of improvement after splenectomy. METHODS Liver cirrhosis was induced by bile duct ligation (BDL). Rats underwent sham operation, splenectomy (Sp group), BDL, or BDL plus splenectomy (BDL + Sp group), and were subjected to experiments at 2 weeks after the operation. Portal venous pressure (PVP) and hepatic tissue blood flow (HTBF) were measured in each group. The plasma concentration of endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS), RhoA and Rho-kinase expressions were studied. RESULTS There were significant differences in PVP (17.9 ± 0.91 vs 23.3 ± 3.91 cmH(2) O; P < 0.01) and HTBF (16.6 ± 1.72 vs 13.3 ± 1.82 mL/min; P < 0.01) between the BDL + Sp and BDL groups. In the liver of BDL rats, eNOS phosphorylation and NOx levels were decreased, accompanied by RhoA activation compared with the BDL + Sp group. Splenectomy decreased serum ET-1 levels, RhoA activation and consequently increased eNOS phosphorylation. CONCLUSION ET-1 derived from the spleen might increase intrahepatic resistance by downregulating Rho signaling in liver cirrhosis. Splenectomy for splenomegaly in liver cirrhosis might partially improve liver function by enhancing intrahepatic microcirculation.
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Affiliation(s)
- Hideo Uehara
- Departments of Surgery and Science Disaster and Emergency Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan
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Seo YS, Shah VH. Pathophysiology of portal hypertension and its clinical links. J Clin Exp Hepatol 2011; 1:87-93. [PMID: 25755320 PMCID: PMC3940250 DOI: 10.1016/s0973-6883(11)60127-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 07/27/2011] [Indexed: 02/08/2023] Open
Abstract
Portal hypertension is a major cause of morbidity and mortality in patients with liver cirrhosis. Intrahepatic vascular resistance due to architectural distortion and intrahepatic vasoconstriction, increased portal blood flow due to splanchnic vasodilatation, and development of collateral circulation have been considered as major factors for the development of portal hypertension. Recently, sinusoidal remodeling and angiogenesis have been focused as potential etiologic factors and various researchers have tried to improve portal hypertension by modulating these new targets. This article reviews potential new treatments in the context of portal hypertension pathophysiology concepts.
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Key Words
- AT, angiotensin
- ET-1, endothelin-1
- HSC, hepatic stellate cell
- HVPG, hepatic venous pressure gradient
- NO, nitric oxide
- PDGF, platelet-derived growth factor
- PIGF, placenta! growth factor
- RAS, renin-angiotensin system
- RCT, randomized controlled trial
- VEGF, vascular endothelial growth factor
- angiogenesis
- eNOS, endothelial nitric oxide synthase
- pathophysiology
- portal hypertension
- sinusoids
- treatment
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Affiliation(s)
- Yeon Seok Seo
- Gastroenterology Research Unit, Mayo Clinic, Rochester, MN - 55905, USA
| | - Vijay H Shah
- Gastroenterology Research Unit, Mayo Clinic, Rochester, MN - 55905, USA,Mayo Clinic Center for Cell Signaling in Gastroenterology, Mayo Clinic, Rochester, MN - 55905, USA,Address for correspondence: Dr Vijay H Shah, Gastroenterology Research Unit, Mayo Clinic, 200 First Street SW, Rochester, MN - 55905, USA
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Arroyo V, Fernández J. Management of hepatorenal syndrome in patients with cirrhosis. Nat Rev Nephrol 2011; 7:517-26. [DOI: 10.1038/nrneph.2011.96] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
INTRODUCTION Renal failure in cirrhosis is a common complication that is associated with poor survival. A rapid diagnosis of the cause of renal failure is mandatory because it is associated with prognosis. AREAS COVERED This review covers the differential diagnosis between hepatorenal syndrome (HRS) and other causes of renal failure, as well as the difficulty in making a correct diagnosis, caused by the differentiation between hepatorenal syndrome and acute tubular necrosis. This review also discusses the multifactorial mechanisms involved in the pathogenesis of HRS. The paper provides diagnostic algorithms to use in clinical practice, emphasized by the fact that some patients may have HRS superimposed on pre-existent renal failure. EXPERT OPINION The correct diagnosis of renal failure is essential to initiate the correct treatment of this complication. In patients with HRS type 1, treatment with vasopressin and albumin is the treatment of choice; however, 50% of patients do not respond to this treatment.
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Affiliation(s)
- Mónica Guevara
- Hospital Clinic Barcelona, Liver Unit, IDIBAPS, CIBERHED, Barcelona, Spain.
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Coelho-Prabhu N, Kamath PS. Current staging and diagnosis of gastroesophageal varices. Clin Liver Dis 2010; 14:195-208. [PMID: 20682229 DOI: 10.1016/j.cld.2010.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Portal hypertension is defined as an increase in hepatic sinusoidal pressure to 6 mm Hg or higher. Cirrhosis is the most common cause of portal hypertension in the western world and results from increased resistance to blood flow at the hepatic sinusoidal level.
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Jin W, Deng L, Zhang Q, Lin D, Zhu J, Chen Y, Chen B, Li J. A canine portal hypertension model induced by intra-portal administration of Sephadex microsphere. J Gastroenterol Hepatol 2010; 25:778-85. [PMID: 20492334 DOI: 10.1111/j.1440-1746.2009.06158.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Big animal models of portal hypertension are important for the research into this disease. The aim of this study was to establish a canine portal hypertension model by intra-portal administration of microspheres. METHODS Sixteen mongrel dogs were assigned to control group and experimental group randomly. The catheterization of portal vein was performed by laparotomy and the outer end of the catheter was fixed subcutaneously in the abdominal wall. The dogs of the experimental group were given intra-portal injections of microspheres at a five-day interval, six times in total. Portal hemodynamics, blood cell counting, liver and renal function test, portography, gastroscopy, liver, spleen and lung histological examination were taken to evaluate the model. RESULTS 1, 2, 3 and 4 months after initial injection of microspheres, portal venous pressure rose from baseline 8.7 +/- 0.7 mmHg to 24.3 +/- 1.6, 20.6 +/- 2.1, 19.0 +/- 1.8 and 17.7 +/- 2.0 mmHg, respectively (P < 0.01). The diameter of portal vein increased from 7.6 +/- 0.3 to 8.6 +/- 0.3 mm, calculated portal resistance increased from 0.46 +/- 0.06 to 1.06 +/- 0.20 (mmHg/mL/min/kg body weight); velocity of portal blood flow decreased from 35.1 +/- 1.7 to 26.1 +/- 2.4 cm/s (P < 0.01, respectively). The animals of experimental group developed marked splenomegaly and profuse portosystemic collateral circulations with normal liver and renal function. CONCLUSION Repeated intra-portal administration of microspheres can induce stable and reproducible chronic portal hypertension in dogs with normal liver and renal functions. This model can meet multiple demands of both basic and clinical research of portal hypertension.
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Affiliation(s)
- Wangxun Jin
- First Affiliated Hospital of Wenzhou Medical College, General Surgery, Wenzhou City, Zhejiang, China
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Van Steenkiste C, Geerts A, Vanheule E, Van Vlierberghe H, De Vos F, Olievier K, Casteleyn C, Laukens D, De Vos M, Stassen JM, Carmeliet P, Colle I. Role of placental growth factor in mesenteric neoangiogenesis in a mouse model of portal hypertension. Gastroenterology 2009; 137:2112-24.e1-6. [PMID: 19751735 DOI: 10.1053/j.gastro.2009.08.068] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 07/31/2009] [Accepted: 09/08/2009] [Indexed: 01/21/2023]
Abstract
BACKGROUND & AIMS Portal hypertension is responsible for the major complications associated with cirrhosis. Angiogenesis has been associated with the pathophysiology of portal hypertension. We investigated the role of placental growth factor (PlGF) and tested the effects of monoclonal antibodies against PlGF (alphaPlGF) in a mouse model of portal hypertension. METHODS Using a mouse model of prehepatic portal hypertension, we measured PlGF levels in the mesenteric tissue at different time points. We used knockout mice and alphaPlGF to determine the role of PlGF in the splanchnic hyperdynamic system and portosystemic collateral formation, examining its effects before and after portal hypertension was induced. RESULTS PlGF was significantly up-regulated in the mesenteric tissue of mice with portal hypertension. Compared with wild-type animals, the vascular density in the mesentery was reduced in PlGF knockout hypertensive mice, preventing collateral formation and attenuation of mesenteric artery flow without affecting portal pressure. In the prevention study, alphaPlGF showed similar findings as in the knockout study. In mice with portal hypertension, administration of alphaPlGF resulted in a 32% decrease in portal pressure, compared with mice given immunoglobulin G(1) (control). CONCLUSIONS Pathologic angiogenesis in the mesenteric tissues of mice with portal hypertension is mediated by PlGF. Blocking PlGF could be an effective strategy for reducing collateral formation and lowering portal pressure; further research into the effects in cirrhosis is warranted.
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Affiliation(s)
- Christophe Van Steenkiste
- Faculty of Medicine and Health Sciences, Department of Hepatology and Gastroenterology, Ghent University, Ghent, Belgium
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Abstract
The use of an operating microscope in rat liver surgery makes it possible to obtain new experimental models and improve the already existing macrosurgical models. Thus, microsurgery could be a very valuable technique to improve experimental models of hepatic insufficiency. In the current review, we present the microsurgical techniques most frequently used in the rat, such as the portacaval shunt, the extrahepatic biliary tract resection, partial and total hepatectomies and heterotopic and orthotopic liver transplantation. Hence, reducing surgical complications allows for perfecting the resulting experimental models. Thus, liver atrophy related to portacaval shunt, prehepatic portal hypertension secondary to partial portal vein ligation, cholestasis by resection of the extrahepatic biliary tract, hepatic regeneration after partial hepatectomies, acute liver failure associated with subtotal or total hepatectomy and finally complications derived from preservation or rejection in orthotopic and heterotopic liver transplantation can be studied in more standardized experimental models. The results obtained are therefore more reliable and facilitates the flow of knowledge from the bench to the bedside. Some of these microsurgical techniques, because of their simplicity, can be performed by researchers without any prior surgical training. Other more complex microsurgical techniques require in-depth surgical training. These techniques are ideal for achieving a complete surgical training and more select microsurgical models for hepatology research.
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Affiliation(s)
- Maria-Angeles Aller
- Surgery I Department, School of Medicine, Complutense University, Madrid, Spain.
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Hackworth WA, Sanyal AJ. Review: Vasoconstrictors for the treatment of portal hypertension. Therap Adv Gastroenterol 2009. [DOI: 10.1177/1756283x09102330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Vasoconstrictors have long been used in an attempt to mitigate the effects of portal hypertension. In this review, we discuss the current understanding of portal hypertension and the use of vasoconstrictors in the management of its sequlae, including variceal hemorrhage, hepatorenal syndrome, and paracentesis-induced circulatory dysfunction. Experimental and clinical evidence for the use of vasoconstrictors is considered, and several exciting recent developments are reviewed.
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Affiliation(s)
- William A. Hackworth
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Arun J. Sanyal
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA,
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12
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Anegawa G, Kawanaka H, Yoshida D, Konishi K, Yamaguchi S, Kinjo N, Taketomi A, Hashizume M, Shimokawa H, Maehara Y. Defective endothelial nitric oxide synthase signaling is mediated by rho-kinase activation in rats with secondary biliary cirrhosis. Hepatology 2008; 47:966-77. [PMID: 18167063 DOI: 10.1002/hep.22089] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In liver cirrhosis, down-regulation of endothelial nitric oxide synthase (eNOS) has been implicated as a cause of increased intrahepatic resistance. We investigated whether Rho-kinase activation is one of the molecular mechanisms involved in defective eNOS signaling in secondary biliary cirrhosis. Liver cirrhosis was induced by bile duct ligation (BDL). We measured mean arterial pressure (MAP), portal venous pressure (PVP), and hepatic tissue blood flow (HTBF) during intravenous infusion of saline (control), 0.3, 1, or 2 mg/kg/hour fasudil for 60 minutes. In BDL rats, 1 and 2 mg/kg/hour fasudil significantly reduced PVP by 20% compared with controls but had no effect on HTBF. MAP was significantly reduced in response to 2 mg/kg/hour fasudil. In the livers of BDL rats, 1 and 2 mg/kg/hour fasudil significantly suppressed Rho-kinase activity and significantly increased eNOS phosphorylation, compared with controls. Fasudil significantly reduced the binding of serine/threonine Akt/PKB (Akt) to Rho-kinase and increased the binding of Akt to eNOS. These results show in secondary biliary cirrhosis that (1) Rho-kinase activation with resultant eNOS down-regulation is substantially involved in the pathogenesis of portal hypertension and (2) Rho-kinase might interact with Akt and subsequently inhibit the binding of Akt to eNOS.
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Affiliation(s)
- Go Anegawa
- Department of Surgery and Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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Sánchez-Patán F, Anchuelo R, Aller MA, Vara E, García C, Nava MP, Arias J. Chronic prehepatic portal hypertension in the rat: is it a type of metabolic inflammatory syndrome? Lipids Health Dis 2008; 7:4. [PMID: 18271959 PMCID: PMC2262079 DOI: 10.1186/1476-511x-7-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 02/13/2008] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND A progressive development of hepatic steatosis with an increase in the lipid hepatocyte content and the formation of megamitochondria have been demonstrated in rats with prehepatic portal hypertension. The aim of this study is to verify the existence of liver and serum lipid metabolism impairments in rats with long-term (2 years) portal hypertension. METHODS Male Wistar rats: Control (n = 10) and with prehepatic portal hypertension by triple partial portal vein ligation (n = 9) were used. Liver content of Triglycerides (TG), phospholipids (PL) and cholesterol and serum cholesterol, lipoproteins (HDL and LDL), TG, glucose and Lipid Binding Protein (LBP) were assayed with specific colorimetric commercial kits. Serum levels of insulin and somatostatin were assayed by RIA. RESULTS The liver content of TG (6.30 +/- 1.95 vs. 4.17 +/- 0.59 microg/ml; p < 0.01) and cholesterol (1.48 +/- 0.15 vs. 1.10 +/- 0.13 microg/ml; p < 0.001) increased in rats with portal hypertension. The serum levels of cholesterol (97.00+26.02 vs. 114.78 +/- 37.72 mg/dl), TG (153.41 +/- 80.39 vs. 324.39 +/- 134.9 mg/dl; p < 0.01), HDL (20.45 +/- 5.14 vs. 55.15 +/- 17.47 mg/dl; p < 0.001) and somatostatin (1.32 +/- 0.31 vs. 1.59 +0.37 mg/dl) decreased, whereas LDL (37.83 +/- 15.39 vs. 16.77 +/- 6.81 mg/dl; p < 0.001) and LBP (308.47 +/- 194.53 vs. 60.27 +/- 42.96 ng/ml; p < 0.001) increased. CONCLUSION Portal hypertension in the rat presents changes in the lipid and carbohydrate metabolisms similar to those produced in chronic inflammatory conditions and sepsis in humans. These underlying alterations could be involved in the development of hepatic steatosis and, therefore, in those described in the metabolic syndrome in humans.
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Affiliation(s)
| | - Raquel Anchuelo
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain
| | - Maria-Angeles Aller
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain
| | - Elena Vara
- Biochemistry and Molecular Biology III Department, School of Medicine, Complutense University of Madrid, Spain
| | - Cruz García
- Biochemistry and Molecular Biology III Department, School of Medicine, Complutense University of Madrid, Spain
| | - Maria-Paz Nava
- Department of Physiology (Animal Physiology II), School of Biology, Complutense University of Madrid, Spain
| | - Jaime Arias
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain
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Aller MA, Arias JL, Cruz A, Arias J. Inflammation: a way to understanding the evolution of portal hypertension. Theor Biol Med Model 2007; 4:44. [PMID: 17999758 PMCID: PMC2206015 DOI: 10.1186/1742-4682-4-44] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 11/13/2007] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death. HYPOTHESIS Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans. CONCLUSION Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.
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Affiliation(s)
- María-Angeles Aller
- Surgery I Department. Medical School, Complutense University, 28040 Madrid, Spain
| | - Jorge-Luis Arias
- Psychobiology Laboratory, School of Psychology, University of Oviedo, Asturias, Spain
| | - Arturo Cruz
- Surgery I Department. Medical School, Complutense University, 28040 Madrid, Spain
- General Surgery Department, Virgen de la Luz General Hospital, 16002 Cuenca, Spain
| | - Jaime Arias
- Surgery I Department. Medical School, Complutense University, 28040 Madrid, Spain
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Abstract
Experimental models are a sine qua non condition for unraveling the specific components and mechanisms contributing to vascular dysfunction and arterial vasodilation in portal hypertension. Moreover, a careful selection of the type of animal model, vascular bed, and methodology is crucial for any investigation of this issue. In this review, some critical aspects related to experimental models in portal hypertension and the techniques applied are highlighted. In addition, a detailed summary of the mechanisms of arterial vasodilation in portal hypertension is presented. First, humoral and endothelial vasodilators, predominantly nitric oxide but also carbon monoxide and endothelium-derived hyperpolarizing factor, and others are discussed. Second, time course and potential stimuli triggering and/or perpetuating splanchnic vasodilation are delineated. Finally, a brief general overview of vascular smooth muscle signaling sets the stage for a discussion on cotransmission, receptor desensitization, and the observed impairment in vasoconstrictor-induced smooth muscle contraction in the splanchnic and systemic circulation during portal hypertension.
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Aller MA, Arias JL, Arias J. The mast cell integrates the splanchnic and systemic inflammatory response in portal hypertension. J Transl Med 2007; 5:44. [PMID: 17892556 PMCID: PMC2034541 DOI: 10.1186/1479-5876-5-44] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 09/24/2007] [Indexed: 02/06/2023] Open
Abstract
Portal hypertension is a clinical syndrome that is difficult to study in an isolated manner since it is always associated with a greater or lesser degree of liver functional impairment. The aim of this review is to integrate the complications related to chronic liver disease by using both, the array of mast cell functions and mediators, since they possibly are involved in the pathophysiological mechanisms of these complications. The portal vein ligated rat is the experimental model most widely used to study this syndrome and it has been considered that a systemic inflammatory response is produced. This response is mediated among other inflammatory cells by mast cells and it evolves in three linked pathological functional systems. The nervous functional system presents ischemia-reperfusion and edema (oxidative stress) and would be responsible for hyperdynamic circulation; the immune functional system causes tissue infiltration by inflammatory cells, particularly mast cells and bacteria (enzymatic stress) and the endocrine functional system presents endothelial proliferation (antioxidative and antienzymatic stress) and angiogenesis. Mast cells could develop a key role in the expression of these three phenotypes because their mediators have the ability to produce all the aforementioned alterations, both at the splanchnic level (portal hypertensive enteropathy, mesenteric adenitis, liver steatosis) and the systemic level (portal hypertensive encephalopathy). This hypothetical splanchnic and systemic inflammatory response would be aggravated during the progression of the chronic liver disease, since the antioxidant ability of the body decreases. Thus, a critical state is produced, in which the appearance of noxious factors would favor the development of a dedifferentiation process protagonized by the nervous functional system. This system rapidly induces an ischemia-reperfusion phenotype with hydration and salinization of the body (hepatorenal syndrome, ascites) which, in turn would reduce the metabolic needs of the body and facilitate its temporary survival.
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Affiliation(s)
- María-Angeles Aller
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain
| | - Jorge-Luis Arias
- Psychobiology Department, School of Psychology, University of Oviedo, Asturias, Spain
| | - Jaime Arias
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain
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Aller MA, Nava MP, Cuellar C, Chivato T, Arias JL, Sanchez-Patan F, de Vicente F, Alvarez E, Arias J. Evolutive phases of experimental prehepatic portal hypertension. J Gastroenterol Hepatol 2007; 22:1127-33. [PMID: 17608859 DOI: 10.1111/j.1440-1746.2007.04876.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Partial portal vein ligation is the experimental model most frequently used to study prehepatic portal hypertension. Different systemic and splanchnic biochemical and histological alterations in short-term (28-45 days) and long-term (12-14 months) evolutive phases which has been described in this experimental model suggest the existence of different pathophysiological mechanisms involved in their production. The enteropathy produced could develop in three phases: an early or acute phase with vasomotor hemodynamic alterations (ischemia-reperfusion associated with intestinal hyperemia, edema and oxidative stress); an intermediate phase with immunological alterations (mesenteric lymphadenopathy, increased mucosal infiltration by mast cells and the hepato-intestinal release of pro- and anti-inflammatory mediators); and a late or chronic phase with intestinal remodeling (vascular and epithelial). The alterations which are produced in these three evolutive phases make it possible to propose an inflammatory etiopathogeny for hypertensive portal enteropathy.
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Affiliation(s)
- Maria-Angeles Aller
- Surgery Department I, Medical School, Complutense University of Madrid, Madrid, Spain
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18
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Aller MA, Vara E, García C, Nava MP, Angulo A, Sánchez-Patán F, Calderón A, Vergara P, Arias J. Hepatic lipid metabolism changes in short- and long-term prehepatic portal hypertensive rats. World J Gastroenterol 2006; 12:6828-34. [PMID: 17106932 PMCID: PMC4087438 DOI: 10.3748/wjg.v12.i42.6828] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To verify the impairment of the hepatic lipid metabolism in prehepatic portal hypertension.
METHODS: The concentrations of free fatty acids, diacylglycerol, triglycerides, and phospholipids were assayed by using D-[U-14C] glucose incorporation in the different lipid fractions and thin-layer chromatography and cholesterol was measured by spectrophotometry, in liver samples of Wistar rats with partial portal vein ligation at short- (1 mo) and long-term (1 year) (i.e. portal hypertensive rats) and the control rats.
RESULTS: In the portal hypertensive rats, liver phospholipid synthesis significantly decreased (7.42 ± 0.50 vs 4.70 ± 0.44 nCi/g protein; P < 0.01) and was associated with an increased synthesis of free fatty acids (2.08 ± 0.14 vs 3.36 ± 0.33 nCi/g protein; P < 0.05), diacylglycerol (1.93 ± 0.2 vs 2.26 ± 0.28 nCi/g protein), triglycerides (2.40 ± 0.30 vs 4.49 ± 0.15 nCi/g protein) and cholesterol (24.28 ± 2.12 vs 57.66 ± 3.26 mg/g protein; P < 0.01).
CONCLUSION: Prehepatic portal hypertension in rats impairs the liver lipid metabolism. This impairment consists in an increase in lipid deposits (triglycerides, diacylglycerol and cholesterol) in the liver, accompanied by a decrease in phospholipid synthesis.
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Affiliation(s)
- Maria-Angeles Aller
- Surgery I Department, School of Medicine, Complutense University of Madrid, Spain.
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19
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Palma MD, Aller MA, Vara E, Nava MP, Garcia C, Arias-Diaz J, Balibrea JL, Arias J. Portal hypertension produces an evolutive hepato-intestinal pro- and anti-inflammatory response in the rat. Cytokine 2006; 31:213-26. [PMID: 15950486 DOI: 10.1016/j.cyto.2005.04.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 12/12/2004] [Accepted: 04/27/2005] [Indexed: 01/29/2023]
Abstract
An inflammatory etiopathogeny can be suggested in portal hypertensive enteropathy since infiltration of the intestinal wall by mononuclear cells has been described in this condition. This work was carried out with the intention of shedding light on this matter. Male Wistar rats were divided into 4 control groups and 4 groups with partial portal vein ligation at 1, 2, 3 and 15 months. TNF-alpha, IL-1beta and IL-10 were quantified in liver and ileum by ELISA. CO and NO were measured in splanchnic and systemic vein by spectrophotometry and Griess reaction, respectively. Expression of constitutive and inducible isoforms of NO and HO were assayed by Western blot in liver and ileum. An increased hepatic release of proinflammatory mediators (TNF-alpha, IL-1beta and NO) associated with intestinal release of anti-inflammatory mediators (IL-10, CO) occurs in an early evolutive phase (1 month) of experimental portal hypertension. On the contrary, in the long-term (15 months), the increase in the intestinal release of proinflammatory mediators (TNF-alpha, IL-1beta) is associated with an increase in the hepatic release of anti-inflammatory mediators (IL-10, CO). These results suggest that experimental prehepatic portal hypertension presents changes in the serum and tissular (liver and small bowel) concentrations of mediators which are considered as pro- and anti-inflammatory.
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20
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López L, Aller MA, Miranda R, Sánchez-Patán F, Nava MP, Arias J, Arias JL. Prehepatic portal hypertension induces alterations in cytochrome oxidase activity in the rat adrenal gland. J INVEST SURG 2006; 19:79-86. [PMID: 16531365 DOI: 10.1080/08941930600567096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
One approach to assess neuroendocrine response to portal hypertension in short-term portal vein-stenosed rats consists in studying metabolic and functional activity patterns in adrenal glands using mitochondrial enzyme cytochrome c oxidase (COX) as a histochemical marker. Male Wistar rats were divided into two groups: a control group (Group I; n = 8), in which the animals did not undergo any operative intervention, and a triple calibrated portal vein stenosis group (TPVS) (Group II; n = 7). The sections of suprarenal glands were histochemically stained for COX and the optical densitometry was measured by a computer image analyzer attached to a microscope. In TPVS rats, COX activity in the adrenal gland cortex is lower than in control rats and affects the fascicular (52.30, 47.16-60.98, vs. 67.12, 60.31-73.89, p = .002), glomerular (49.68, 46.19-53.56 vs. 70.47, 64.64-73.51, p < .001), and reticular (47.35, 35.63-54.39, vs. 55.37, 49.76-58.97; p < .05) layers. In contrast, COX activity in the adrenal gland medulla is similar in TPVS rats and in control rats (29.91, 29.54-31.18, vs. 29.67, 28.95-30.23). The changes in adrenocortical COX activity in short-term-TPVS rats could constitute a pathogenic factor for both splanchnic and systemic hyperdynamic circulations, described in this experimental model of prehepatic portal hypertension.
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Affiliation(s)
- Laudino López
- Psychobiology Laboratory, School of Psychology, University of Oviedo, Principado de Asturias, Spain
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21
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Katsuta Y, Zhang XJ, Ohsuga M, Akimoto T, Komeichi H, Shimizu S, Inami T, Miyamoto A, Satomura K, Takano T. Hemodynamic features of advanced cirrhosis due to chronic bile duct ligation. J NIPPON MED SCH 2005; 72:217-25. [PMID: 16113492 DOI: 10.1272/jnms.72.217] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
AIM The aim of the present study was to compare the hemodynamic features of portal hypertension in rats with early cirrhosis with those of rats with advanced cirrhosis following common bile duct ligation (CBDL). METHODS A total of 53 male Sprague-Dawley rats were used. Hemodynamics were evaluated under conscious and unrestrained conditions 4 weeks and 8 weeks after CBDL, and 4 weeks after a sham operation. Arterial pressure and portal pressure were measured directly via catheters placed in the right femoral artery and main portal vein, respectively. The cardiac index and organ (splanchninc organs, brain, kidneys and lungs) blood flow were determined by the reference sample method using (141)Ce-labeled microspheres (15 mum in diameter). Arterial levels of endothelin-1 and nitrate/nitrite, as well as liver function variables, were also determined. RESULTS Portal pressure was significantly higher 8 weeks after CBDL (15.8+/-2.1, n=8) than 4 weeks after CBDL (13.9+/-2.1 mmHg, n=12, p<0.05), and the hyperdynamic circulation of the early period was attenuated (p<0.05). Although hepatic artery blood flow 4 and 8 weeks after CBDL was higher than that after sham operation (p<0.05), portal territory blood flow was not increased. There was a significant positive correlation between portal pressure and portal territory blood flow 8 weeks after CBDL (r=0.822, n=8, p=0.012). In rats with anemia 4 weeks after CBDL, the hemoglobin concentration was negatively correlated with portal territory blood flow (r=-0.597, n=12, p=0.040). CONCLUSION Portal pressure was higher 8 weeks after CBDL than 4 weeks after CBDL and increased with portal territory blood flow, suggesting that portal hypertension is maintained by a mechanism consistent with the forward flow theory. Anemia might exacerbate the hyperdynamic systemic circulation 4 weeks after CBDL.
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Affiliation(s)
- Yasumi Katsuta
- First Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
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22
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Birney Y, Redmond EM, Sitzmann JV, Cahill PA. Eicosanoids in cirrhosis and portal hypertension. Prostaglandins Other Lipid Mediat 2003; 72:3-18. [PMID: 14626493 DOI: 10.1016/s1098-8823(03)00080-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the last decade, the knowledge of the pathogenesis of portal hypertension and cirrhosis has increased dramatically. In portal hypertension, almost all the known vasoactive systems/substances are activated or increased and the most recent studies have stressed the importance of the endothelial factors, in particular, prostaglandins. Prostaglandins are formed following the oxygenation of arachidonic acid by the cyclooxygenase (Cox) pathway. An important consideration in portal hypertension and cirrhosis in the periphery is the altered hemodynamic profile and its contributory role in controlling endothelial release of these vasoactive substances. Prostaglandins are released from the endothelium in response to both humoral and mechanical stimuli and can profoundly affect both intrahepatic and peripheral vascular resistance. Within the liver, intrahepatic resistance is altered due to a diminution in sinusoidal responsiveness to vasodilators and an increase in prostanoid vasoconstrictor responsiveness. This review will examine the contributory role of both hormonal and/or hemodynamic force-induced changes in prostaglandin production and signaling in cirrhosis and portal hypertension and the consequence of these changes on the structural and functional response of both the vasculature and the liver.
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Affiliation(s)
- Yvonne Birney
- School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland
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23
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Theodorakis NG, Wang YN, Skill NJ, Metz MA, Cahill PA, Redmond EM, Sitzmann JV. The role of nitric oxide synthase isoforms in extrahepatic portal hypertension: studies in gene-knockout mice. Gastroenterology 2003; 124:1500-8. [PMID: 12730888 DOI: 10.1016/s0016-5085(03)00280-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Considerable debate exists concerning which isoform of nitric oxide synthase (NOS) is responsible for the increased production of NO in PHT. We used the portal vein ligation model of PHT in wild-type and eNOS- or iNOS-knockout mice to definitively determine the contribution of these isoforms in the development of PHT. METHODS The portal vein of wild-type mice, or those with targeted mutations in the nos2 gene (iNOS) or the nos3 gene (eNOS), was ligated and portal venous pressure (Ppv), abdominal aortic blood flow (Qao), and portosystemic shunt determined 2 weeks later. RESULTS In wild-type mice, as compared with sham-operated controls, portal vein ligation (PVL) resulted in a time-dependent increase in Ppv (7.72 +/- 0.37 vs 17.57 +/- 0.51 cmH(2)O, at 14 days) concomitant with a significant increase in Qao (0.12 +/- 0.003 vs 0.227 +/- 0.005 mL/min/g) and portosystemic shunt (0.47% +/- 0.01% vs 84.13% +/- 0.09% shunt). Likewise, PVL in iNOS-deficient mice resulted in similar increases in Ppv, Qao, and shunt development. In contrast, after PVL in eNOS-deficient animals, there was no significant change in Ppv (7.52 +/- 0.22 vs 8.07 +/- 0.4 cmH(2)0) or Qao (0.111 +/- 0.01 vs 0.14 +/-.023 mL/min/g). However, eNOS (-/-) mice did develop a substantial portosystemic shunt (0.33% +/- 0.005% vs 84.53% +/- 0.19% shunt), comparable to that seen in wild-type animals after PVL. CONCLUSIONS These data support a key role for eNOS, rather than iNOS, in the pathogenesis of PHT.
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24
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Potenza MA, Botrugno OA, De Salvia MA, Lerro G, Nacci C, Marasciulo FL, Andriantsitohaina R, Mitolo-Chieppa D. Endothelial COX-1 and -2 differentially affect reactivity of MVB in portal hypertensive rats. Am J Physiol Gastrointest Liver Physiol 2002; 283:G587-94. [PMID: 12181171 DOI: 10.1152/ajpgi.00391.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Expression of constitutive and inducible cyclooxygenase (COX-1 and COX-2, respectively) and the role of prostanoids were investigated in the aorta and mesenteric vascular bed (MVB) from the portal vein-ligated rat (PVL) as a model of portal hypertension. Functional experiments were carried out in MVB from PVL and sham-operated rats in the absence or presence of the nonselective COX inhibitor indomethacin or the selective inhibitors of COX-1 (SC-560) or COX-2 (NS-398). Western blots of COX-1 and COX-2 proteins were evaluated in aorta and MVB, and PGI(2) production by enzyme immunoassay of 6-keto-PGF(1alpha) was evaluated in the aorta. In the presence of functional endothelium, decreased contraction to norepinephrine (NE) and increased vasodilatation to ACh were observed in MVB from PVL. Exposure of MVB to indomethacin, SC-560, or NS-398 reversed the hyporeactivity to NE and the increased endothelial vasodilatation to ACh in PVL, with NS-398 being more potent than the other two inhibitors. Upregulation of COX-1 and COX-2 expressions was detected in aorta and MVB from PVL portal hypertensive rats, and increased production of 6-keto-PGF(1alpha) was observed in aorta from portal hypertensive rats. These results suggest that generation of endothelial vasodilator prostanoids, from COX-1 and COX-2 isoforms, accounts for the increased mesenteric blood flow in portal hypertension.
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Affiliation(s)
- M A Potenza
- Section of Pharmacology, Department of Pharmacology and Human Physiology, Medical School, University of Bari, 70124 Bari, Italy
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25
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Abstract
The molecular basis of the vascular wall abnormalities that contribute to development of portal hypertension are an area of active investigation. Studies to date suggest that diminution in eNOS-derived NO production in liver contributes to this process by causing increased intrahepatic resistance. This process seems to be mediated through inhibitory posttranslational regulatory mechanisms of eNOS. Endothelin-1 signaling is also increased in the intrahepatic vasculature. The mechanisms responsible for increased ET-1 signaling include increased ET-1 production and increased ET-A receptor expression, particularly within hepatic stellate cells, although the stimulus responsible for activation of the ET-1 system remains uncertain. In the splanchnic circulation, increases in eNOS-derived NO contribute to increased portal venous inflow through transcriptional and posttranslational regulation of eNOS. Development of the porto-systemic collateral circulation characteristic of portal hypertension occurs through a combination of NO-dependent dilation of preexisting vessels and through growth factor-mediated angiogenesis and neovascularization (Fig. 3). Further studies in vascular wall biology are continuing to elucidate more clearly the molecular mechanisms of portal hypertension. The [figure: see text] mechanism by which eNOS-derived NO production is increased in the splanchnic arteriolar endothelial cell but decreased in the liver endothelial cell and the role of specific ET receptor subtypes in the mechanism of activation of the ET-1 system and its effect on contractile cells in liver cirrhosis are areas that require further investigation. Further studies are needed to determine the intrahepatic site of pressure and perfusion regulation, be it the hepatic sinusoid and its unique, specialized cell types or the endothelial and smooth muscle cells in the hepatic and portal venules. The role of more recently delineated vasoactive pathways such as urotensin-II/GPR 14 and anandamide/CB1 receptor in portal hypertension must be examined. Most importantly, future studies must focus on novel experimental therapies, using pharmacologic and genetic approaches to modulate these vascular biologic systems and thereby to ameliorate complications and symptoms relating to portal hypertension in patients with cirrhosis.
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Affiliation(s)
- V Shah
- Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
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26
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Abstract
Portal hypertension (PHT) is a common clinical syndrome associated with chronic liver diseases; it is characterized by a pathological increase in portal pressure. Pharmacotherapy for PHT is aimed at reducing both intrahepatic vascular tone and elevated splanchnic blood flow. Due to the altered hemodynamic profile in PHT, dramatic changes in mechanical forces, both pressure and flow, may play a pivotal role in controlling endothelial and vascular smooth muscle cell signaling, structure, and function in cirrhotics. Nitric oxide, prostacyclin, endothelial-derived contracting factors, and endothelial-derived hyperpolarizing factor are powerful vasoactive substances released from the endothelium in response to both humoral and mechanical stimuli that can profoundly affect both the function and structure of the underlying vascular smooth muscle. This review will examine the contributory role of hormonal- and mechanical force-induced changes in endothelial function and signaling and the consequence of these changes on the structural and functional response of the underlying vascular smooth muscle. It will focus on the pivotal role of hormonal and mechanical force-induced endothelial release of vasoactive substances in dictating the reactivity of the underlying vascular smooth muscle, i.e., whether hyporeactive or hyperreactive, and will examine the extent to which these substances may exert a protective and/or detrimental influence on the structure of the underlying vascular smooth muscle in both a normal hemodynamic environment and following hemodynamic perturbations typical of PHT and cirrhosis. Finally, it will discuss the intracellular processes that regulate the release/expression of these vasoactive substances and that control the transformation of this normally protective cell to one that may promote the development of vasculopathy in PHT.
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Affiliation(s)
- P A Cahill
- School of Biotechnology, Dublin City University, Glasnevin Dublin 9, Ireland.
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27
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Abstract
Altered regulation of receptors on the vascular smooth muscle has been proposed as one of the mechanisms that may account for the vascular abnormalities in patients with cirrhosis of the liver. Impaired contractility and down-regulation of contractile receptors have been demonstrated in cirrhotic patients and animal models, although interpretation of the literature is hampered by methodological variation and conflicting results. There is little evidence, however, that receptor down-regulation is the cause of contractile dysfunction in either patients or animal models. Receptor desensitisation may contribute to impaired contraction in human arteries, but further investigation is required to confirm this possibility.
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MESH Headings
- Animals
- Calcium/chemistry
- Calcium/metabolism
- Down-Regulation
- Humans
- Liver Cirrhosis/physiopathology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiopathology
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/biosynthesis
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/drug effects
- Receptors, Cell Surface/physiology
- Second Messenger Systems/physiology
- Signal Transduction
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- P W Hadoke
- Endocrinology Unit, Department of Medical Sciences, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, Scotland, UK.
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28
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Aller Reyero M, Nava Hidalgo M, Diéguez Fernández B, Palma Mezquida M, Arias Pérez J, Arias Pérez J. Hipertensión portal prehepática crónica en la rata por triple ligadura estenosante portal. Cir Esp 2001. [DOI: 10.1016/s0009-739x(01)71704-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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29
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Fraser GM, Blendis LM, Smirnoff P, Sikular E, Niv Y, Schwartz B. Portal hypertension induces sodium channel expression in colonocytes from the distal colon of the rat. Am J Physiol Gastrointest Liver Physiol 2000; 279:G886-92. [PMID: 11052984 DOI: 10.1152/ajpgi.2000.279.5.g886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cellular mechanisms for Na(+) retention in portal hypertension are undefined, but epithelial Na(+) channels (ENaC) may be involved. Under high-salt diet, ENaC are absent from distal colon of rat but can be induced by mineralocorticoids such as aldosterone. Presence of rat ENaC was determined by amiloride inhibition of (22)Na(+) uptake in surface colonocytes 7 and 14 days after partial portal vein ligation (PVL) or sham surgery. At both times, uptake inhibition was significantly increased in PVL rats. Presence of mRNA transcripts, determined by RT-PCR, demonstrated that channel alpha- and gamma-subunits were similarly expressed in both groups but that beta-subunit mRNA was increased in PVL rats. This confirms that there was induction of rat ENaC and indicates that beta-subunit has a regulatory role. Urinary Na(+) was decreased for 3 days after PVL but was not different at other times, and serum aldosterone levels were elevated at 7 days, at a time when urinary Na(+) output was similar to that of sham-operated rats. We conclude that PVL leads to induction of ENaC in rat distal colon. An increase in aldosterone levels may prevent natiuresis and is probably one of several control mechanisms involved in Na(+) retention in portal hypertension.
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Affiliation(s)
- G M Fraser
- Department of Gastroenterology, Rabin Medical Center, Beilinson Campus and Sackler Faculty of Medicine, University of Tel-Aviv, Petach Tikva 49100, Israel.
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30
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Wattanasirichaigoon S, Gordon FD, Resnick RH. Hyperdynamic circulation in portal hypertension: a comparative model of arterio-venous fistula. Med Hypotheses 2000; 55:77-87. [PMID: 11021333 DOI: 10.1054/mehy.1999.1034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Complications of portal hypertension remain perplexing physiologic phenomena in the understanding of shunt hemodynamics with multiple theories. Hyperdynamic circulation was also found in sepsis, chronic anemia and arterio-venous (A-V) fistula which relate to an increase in nitric oxide. We hypothesize that portosystemic collaterals may mimic an A-V fistula in which the high-pressure portal blood connects with the lower pressure systemic venous circulation. Although these collaterals decompress the portal circulation, a number of secondary hemodynamic phenomena occur which increase portal blood flow and tend to counteract the portal hypotensive effect of the portosystemic shunt. The consequent increases in cardiac output and portal blood flow perfuse the compromised liver. As portal blood flow increases, collateral flow increases and is nearly totally shunted in the systemic circulation. This shunt may eventually introduce a vicious cycle of hyperdynamic circulation into a compromised host. Ultimately, high-output cardiac failure occurs, leading to cirrhotic cardiomyopathy.
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Affiliation(s)
- S Wattanasirichaigoon
- Department of Surgery, Faculty of Medicine, Srinakharinwirot University, Vajira Hospital, Bangkok, Thailand.
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31
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Abstract
Increased resistance to portal blood flow is the primary factor in the pathophysiology of portal hypertension, and is mainly determined by the morphological changes occurring in chronic liver diseases. This is aggravated by a dynamic component, due to the active-reversible- contraction of different elements of the porto-hepatic bed. A decreased synthesis of NO in the intrahepatic circulation is the main determinant of this dynamic component. This provides a rationale for the use of vasodilators to reduce intrahepatic resistance and portal pressure. Another factor contributing to aggravate the portal hypertension is a significant increase in portal blood flow, caused by arteriolar splanchnic vasodilation and hyperkinetic circulation. Splanchnic arteriolar vasodilation is a multifactorial phenomenon, which may involve local (endothelial) mechanisms as well as neurogenic and humoral pathways. Most pharmacological treatments have been aimed at correcting the increased portal blood inflow by the use of splanchnic vasoconstrictors, such as beta-blockers, vasopressin derivatives and somatostatin. Several studies have demonstrated that changes in the hepatic venous pressure gradient (HVPG) during maintenance therapy are useful to identify those patients who are going to have a variceal bleeding or rebleeding. The wide individual variation in the HVPG response to pharmacological treatment makes it desirable to schedule follow-up measurements of HVPG during pharmacological therapy. A priority for research in the forthcoming years is to develop accurate non-invasive methods to assess prognosis, which can be used to substitute or as surrogate indicators of the HVPG response. In the clinical management of portal hypertension, beta-blockers are at present the only accepted treatment for the prevention of variceal bleeding. Whether the association of isosorbide-5-mononitrate will improve the high efficacy of beta-blockers is questionable. The efficacy of more aggressive techniques, such as endoscopic band ligation, should be further tested against beta-blockers in patients with a high risk of bleeding. In the treatment of acute variceal bleeding, administration of somatostatin or terlipressin is an established therapy. It may be used alone or, preferably, as an initial treatment before sclerotherapy or endoscopic band ligation. No more than two sessions of endoscopic treatment should be used to control the bleeding. If the bleeding is not easily controlled, other alternatives such as transjugular intrahepatic portosystemic shunts (TIPS) or derivative surgery should be considered, the former being the best in patients with poor liver function. Recent studies suggest that early measurement of HVPG during variceal bleeding may be used as a guide for therapeutic decisions in the treatment of patients with acute variceal bleeding. Those patients with a high HVPG have a high risk of poor evolution, and may be candidates for more intensive and aggressive therapy, such as surgery or TIPS. Those with lower HVPG have a very high probability of an uneventful evolution, and may thus be managed more conservatively using medical and endoscopic treatments. Pharmacological agents (propranolol or nadolol), endoscopic treatment (preferably banding ligation) or surgery can be used to prevent rebleeding. A pending task for the new millennium is to assess whether the early treatment of asymptomatic, compensated cirrhotic patients with portal pressure reducing agents can prevent the development of esophageal varices and of other complications of portal hypertension.
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Affiliation(s)
- J Bosch
- Hepatic Hemodynamic Laboratory, IMD, Hospital Clinic, IDIBAPS, University of Barcelona, Spain
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32
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Tsugawa K, Hashizume M, Migou S, Kishihara F, Kawanaka H, Tomikawa M, Sugimachi K. A selective cyclo-oxygenase-2 inhibitor, NS-398, may improve portal hypertension without inducing gastric mucosal injury. J Gastroenterol Hepatol 1999; 14:642-51. [PMID: 10440208 DOI: 10.1046/j.1440-1746.1999.01930.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND AIMS Prostacyclin has been shown to play a role in hyperdynamic circulation in portal hypertension. Recently, a new subtype of cyclo-oxygenase (COX), COX-2, which acts as an inducible synthase in response to various stimuli. The aim of this study was to investigate whether COX-2 contributes to portal hypertension and whether a COX-2 blockade induces the same sort of gastric mucosal injury as a COX-1 blockade. METHODS Portal hypertension (PHT) in rats was induced by a two-step ligation of the portal vein. The mean arterial pressure (MAP), portal pressure (PP), visceral blood flow volume (BFV), serum levels of 6-keto-prostaglandin F1alpha (PGF1alpha), thromboxane B2 (TXB2) and gastric mucosal injury induced by pure ethanol were all measured in PHT rats receiving different inhibitors (indomethacin, a highly selective COX-1 inhibitor; NS-398, a highly selective COX-2 inhibitor). Control rats treated by a sham operation were also studied. RESULTS The NS-398 administration significantly decreased PP to the same extent as indomethacin at doses of 5 and 10 mg/kg in PHT rats after a 60 min administration, while neither inhibitor affected the control rats. Both inhibitors significantly increased PP after a 30 min administration in the PHT and control rats at a dose of 5 mg/kg while both inhibitors significantly decreased PP after 60 min administration only in the PHT rats. Portal vein ligation treatment induced a significant increase in PP and BFV of the portal vein, gastric mucosa, oesophageal mucosa and the serum levels of 6-keto-PGF1alpha and TXB2, while portal vein ligation treatment induced a significant decrease in BFV of the liver. Both blockades increased MAP and decreased PP and BFV in the splanchnic area and decreased the serum level of 6-keto-PGF1alpha and TXB2 in the PHT rats, while neither blockade modified any parameters in the control rats, except that indomethacin administration significantly decreased the BFV of the gastric mucosa. Indomethacin administration significantly increased the ulcer index (UI). The NS-398 had no effect on UI in either the PHT or control rats. Only indomethacin significantly increased the number of rats demonstrating gastric mucosal long lesions (> 2 cm) in the PHT rats. CONCLUSION In the PHT rats, prostaglandin seemed to contribute to portal hypertension. Both COX blockades reduced PP and BFV of the portal vein and gastric mucosa. NS-398, a selective COX-2 inhibitor, may, therefore, improve portal hypertension without inducing gastric mucosal injury.
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Affiliation(s)
- K Tsugawa
- Department of Surgery II, Faculty of Medicine, Kyushu University, Fukuoka, Japan
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Battarbee HD, Zavecz JH, Grisham MB, Maloney RE, Chandler LJ, Mercer JW, Cady FM. Cardiac impairment and nitric oxide synthase activity in the chronic portal vein-stenosed rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G363-72. [PMID: 9950809 DOI: 10.1152/ajpgi.1999.276.2.g363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Decreased cardiac contractility and beta-adrenergic responses have been observed in the chronic portal vein-stenosed (PVS) rat. Because nitric oxide (NO) may be increased in PVS and has been recognized as a negative inotropic agent, we investigated the induction of NO synthase (NOS2) and/or changes in constitutive NOS (NOS3) as factors in the cardiac dysfunction of the PVS rat. Ten to twelve days after portal vein stenosis or sham operation, cardiac function was evaluated in paced left ventricular papillary muscles (LVPM) and right ventricular strips (RV). To determine if NO modulation of contractile function was altered in PVS, we examined the increase in developed tension produced by the effect of Nomega-nitro-L-arginine (L-NNA) on the myocardial force-frequency relationship. Cardiac tissue NOS2 and NOS3 activities were assayed, Western blot analyses of NOS2 and NOS3 expression were performed, and circulating nitrate-nitrite (NOX) levels (an indicator of in vivo NOS activity) were assayed. Basal LVPM and RV contractile indexes were significantly reduced in PVS (30-50%), without a change in the relaxation rate. No between-group differences in the cardiac NOS2 or NOS3 enzymatic activities of PVS and sham-operated (SO) rats were observed. Western blots revealed no cardiac NOS2 expression in either SO or PVS rats. In contrast, NOS3 was expressed in both SO and PVS rats, but there was no quantitative difference in expression between the two groups. Changes in the cardiac force-frequency relationship (staircase effect) after L-NNA were consistent with NOS3 modulation of contractile function in both SO and PVS rats, but there was no between-group difference in the modulation. Circulating NOX concentrations did not differ between SO and PVS rats. In conclusion, protein expression data, enzymatic assays, end-product assays, and functional data indicate that between-group differences in NOS2 and NOS3 activity are not responsible for the cardiac impairment that has been observed in the chronic PVS rat.
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Affiliation(s)
- H D Battarbee
- Department of Molecular and Cellular Physiology, Louisiana State University Medical Center, Shreveport, Louisiana 71130-3932, USA
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Imamura H, Rocheleau B, Côté J, Huet PM. Long-term consequence of rat orthotopic liver transplantation with and without hepatic arterial reconstruction: a clinical, pathological, and hemodynamic study. Hepatology 1997; 26:198-205. [PMID: 9214470 DOI: 10.1002/hep.510260126] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Our aim was to investigate the time-related changes in various parameters following orthotopic rat liver transplantation with (AOLT) and without (NOLT) arterial reconstruction in male Lewis rats. Body weight and biochemical parameters were measured weekly, and a liver biopsy was obtained at 4, 8, and 12 weeks. Hemodynamics were evaluated at 12 weeks using the microsphere technique and compared with matched controls. Following AOLT, rats gained weight normally without any noticeable complication. In NOLT, two subgroups (NOLT-1 and NOLT-2) could clearly be identified retrospectively. In the NOLT-1 group, the body weight increased normally, although animals presented transient cholestasis. In these rats, the ductular proliferation found at 4 weeks had regressed by the 12th week with near-normal biopsies. By contrast, in the NOLT-2 group, rats did not gain body weight and had persistent cholestasis. Marked ductular proliferation with increasing fibrosis was observed, resulting in a secondary biliary cirrhosis by the 12th week. Surprisingly, rearterialization of the grafted liver occurred in both NOLT-1 and NOLT-2 irrespective of their clinical course. All transplanted rats showed portal hypertension with marked portosystemic shunts, probably caused by the portal cuff. However, a hyperdynamic circulatory state was only observed in the NOLT-2 group with cirrhotic changes. These findings further show the combined role of an intact hepatic innervation and of hepatocellular insufficiency in the genesis of the hyperdynamic circulatory state associated with portal hypertension.
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Affiliation(s)
- H Imamura
- André-Viallet Clinical Research Center, Department of Medicine, Hôpital Saint-Luc, and Université de Montréal, Québec, Canada
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Rodriguez-Roisin R, Roca J. Hepatopulmonary syndrome: the paradigm of liver-induced hypoxaemia. BAILLIERE'S CLINICAL GASTROENTEROLOGY 1997; 11:387-406. [PMID: 9395754 DOI: 10.1016/s0950-3528(97)90046-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The current chapter deals with the concept, clinical manifestations and diagnostic tools of the hepatopulmonary syndrome (HPS) and highlights its most salient pathophysiological, mechanistic and therapeutic aspects. Defined as a clinical triad, including a chronic liver disorder, pulmonary gas exchange abnormalities and generalized pulmonary vascular dilatations, in the absence of intrinsic cardiopulmonary disease, this entity is currently growing in interest with both clinicians and surgeons. The combination of arterial hypoxaemia, high cardiac output with normal or low pulmonary artery pressure, and finger clubbing in a patient with advanced liver disease should strongly suggest the diagnosis of HPS. Its potential high prevalence together with failure of numerous therapeutic approaches depicts a life-threatening unique clinical condition that may dramatically benefit with an elective indication of liver transplantation (LT). A better orchestration of the concepts of the pathophysiology of this lung-liver interplay may foster our knowledge and improve the clinical management and indications of LT.
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Affiliation(s)
- R Rodriguez-Roisin
- Departament de Medicina, Hospital Clínic, Universitat de Barcelona, Spain
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Gupta TK, Chen L, Groszmann RJ. Pathophysiology of portal hypertension. BAILLIERE'S CLINICAL GASTROENTEROLOGY 1997; 11:203-19. [PMID: 9395744 DOI: 10.1016/s0950-3528(97)90036-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Portal hypertension is a common clinical syndrome associated with chronic liver diseases and is characterized by a pathological increase in portal pressure. Increase in portal pressure is because of an increase in vascular resistance and an elevated portal blood flow. The site of increased intrahepatic resistance is variable and is dependent on the disease process. The site of obstruction may be: pre-hepatic, hepatic, and/or post-hepatic. In addition, part of the increased intrahepatic resistance is because of increased vascular tone. Another important factor contributing to increased portal pressure is elevated blood flow. Peripheral vasodilatation initiates the classical profile of decreased systemic resistance, expanded plasma volume, elevated splanchnic blood flow and elevated cardiac index. The elevated portal pressure leads to formation of portosystemic collaterals and oesophageal varices. Pharmacotherapy for portal hypertension is aimed at reducing both intrahepatic vascular tone and elevated splanchnic blood flow.
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Affiliation(s)
- T K Gupta
- Hepatic Hemodynamic Laboratory, VA Medical Center, West Haven, CT 06516, USA
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Agusti AG, Roca J, Rodriguez-Roisin R. Mechanisms of gas exchange impairment in patients with liver cirrhosis. Clin Chest Med 1996; 17:49-66. [PMID: 8665790 DOI: 10.1016/s0272-5231(05)70298-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This article reviews the basic pathophysiologic mechanisms underlying the abnormal pulmonary gas exchange often seen in patients with cirrhosis. To summarize, the following keypoints seem appropriate: (1) Patients with cirrhosis have a low pulmonary vascular tone characterized by a poor or absent hypoxic pressor response. This results in a marked dilation of the pulmonary vasculature. (2) This abnormal pulmonary vascular tone, independently of airway disease, causes VA/Q mismatch and mild to moderate hypoxemia. Yet, as liver disease progresses and hepatocellular function deteriorates, more severe degrees of intrapulmonary shunt emerge and, probably, O2 diffusion limitation ensues, causing severe respiratory failure (see Table 1). (3) At rest, the high cardiac output and minute ventilation of cirrhosis minimize the degree of arterial hypoxemia that otherwise would be expected from the observed degree of both VA/Q inequality and intrapulmonary shunt. During exercise, the relative "normalization' (with respect to metabolic demands) of the hemodynamic and ventilatory status of the patient explains the fall in PaO2. (4) A clear pathogenic mechanism of these pathophysiologic abnormalities is still lacking, although available evidence suggests that both the liver and the endothelial cells may play a pivotal role in the regulation of the pulmonary vascular tone in these patients. (5) To date, no pharmacologic intervention has been effective in treating hypoxemia in these patients. Yet liver transplantation helps in most of them. This observation reinforces the functional nature of the gas exchange abnormalities of cirrhosis.
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Affiliation(s)
- A G Agusti
- Pulmonary Service, Hospital Universitari Son Dureta, Mallorca (AGNA), Spain
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Michielsen PP, Boeckxstaens GE, Sys SU, Herman AG, Pelckmans PA. The role of increased nitric oxide in the vascular hyporeactivity to noradrenaline in long-term portal vein ligated rats. J Hepatol 1995. [PMID: 8550999 DOI: 10.1016/s0168-8278(95)80014-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
To test the possible role of nitric oxide production in long-term portal vein ligation in the rat, where the hyperdynamic circulation was reported to be absent, in vivo experiments on isolated thoracic aortic rings from partial portal vein ligated or sham-operated rats were performed, 6 months postoperatively. The concentration-response curves to noradrenaline of both intact and endothelium-denuded rings from portal hypertensive rats were significantly shifted to the right as compared to those from sham-operated animals. In intact rings, addition of NG-nitro-L-arginine, a specific inhibitor of nitric oxide synthase, resulted in a significant shift of the curves to the left in sham-operated and portal vein ligated rats. In endothelium-denuded rings, addition of NG-nitro-L-arginine resulted in a significant shift of the curves to the left in portal vein ligated but not in sham-operated animals. After blockade of the nitric oxide biosynthesis with NG-nitro-L-arginine, the negative logarithm of the concentration of nonadrenaline causing half-maximal response did not significantly differ any more between portal vein ligated and sham-operated rats; in endothelium-denuded rings hyporeactivity to noradrenaline persisted in portal vein ligated rats. Only in the intact rings did NG-nitro-L-arginine significantly increase the maximal contractions. No differences were demonstrated in endothelium-dependent relaxations to acetylcholine between sham-operated and portal hypertensive animals. From these results, it can be concluded that in vitro aortic hyporeactivity to noradrenaline is still present in long-term portal vein ligated rats, and that it results at least partially from activation of the L-arginine: nitric oxide pathway in the aortic vascular wall.
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Affiliation(s)
- P P Michielsen
- Division of Gastroenterology, Faculty of Medicine, University of Antwerp (UIA), Belgium
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39
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Johnson TJ, Quigley EM, Adrian TE, Jin G, Rikkers LF. Glucagon, stress, and portal hypertension. Plasma glucagon levels and portal hypertension in relation to anesthesia and surgical stress. Dig Dis Sci 1995; 40:1816-23. [PMID: 7648985 DOI: 10.1007/bf02212707] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Glucagon has been proposed as the mediator of splanchnic hyperemia in portal hypertension. Employing an assay specific for pancreatic glucagon, we reevaluated the relationship between this peptide and portal hypertension in the portal vein (PV)-stenosed rat model addressing, in particular, the effects of anesthesia and surgical stress. Plasma glucagon levels were similar in sham-operated and portal hypertensive rats: glucagon, sham vs PV stenosed: 110.7 +/- 17.1 pmol/liter vs 140.6 +/- 23.3 pmol/liter (NS). Furthermore, plasma levels of glucagon and the related peptide VIP were not significantly influenced by anesthesia or surgical stress, and levels remained similar under all conditions in sham-operated and PV-stenosed animals. We conclude that pancreatic glucagon is not elevated in the PV-stenosed rat; differences between these results and those describing hyperglucagonemia in this model cannot be explained on the basis of a differential response to stress but may reflect differences in glucagon assay system.
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Affiliation(s)
- T J Johnson
- Department of Surgery, University of Nebraska Medical Center, Omaha 68198-2000, USA
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40
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Johnson TJ, Quigley EM, Shaffer CJ, Adrian TE, Rikkers LF. Effects of portal vein stenosis and superior mesenteric vein ligation on mesenteric venous pressure and porta-systemic shunting in the rat. J INVEST SURG 1994; 7:477-83. [PMID: 7893634 DOI: 10.3109/08941939409015364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We studied the relative contributions of splanchnic congestion and porta-systemic shunting to the maintenance of experimental portal venous hypertension. Three groups of rats were prepared: portal vein-stenosed, superior mesenteric vein-ligated and sham operated. Though elevated in both operated groups compared to controls, mesenteric venous pressure was highest in the portal vein-stenosed animals (PV vs SMV vs Sham: 19.6 +/- 1.3 vs 15.6 +/- 0.7 vs 13 +/- 0.6; p < .05 PV and SMV vs Sham, and PV vs SMV) despite the presence of 50% porta-systemic shunting in the portal vein-stenosed animals. Shunting was negligible in the other two groups. Peripheral plasma glucagon and vasoactive intestinal peptide (VIP) levels were similar in all three groups. We conclude that mesenteric congestion alone plays a minor role in the pathogenesis of portal hypertension, which may instead be related to the porta-systemic shunting of vasoactive substances other than glucagon and VIP.
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Affiliation(s)
- T J Johnson
- Department of Surgery, University of Nebraska Medical Center, Omaha
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41
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Affiliation(s)
- J M Pak
- Gastroenterology Research Group, University of Calgary, Canada
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42
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Wheatley AM, Zhao D, Höflin FG, Stuart ET, Guastella T, Czerniak A, Blumgart LH. Measurement of hepatobiliary function and hepatic hemodynamics in portally hypertensive rats. ACTA ACUST UNITED AC 1993. [DOI: 10.1007/bf02602091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Sitzmann JV, Campbell KA, Wu Y, Cameron JL. Effect of portosystemic shunting on PGI2 and glucagon levels in humans. Ann Surg 1993; 217:248-52. [PMID: 8452403 PMCID: PMC1242777 DOI: 10.1097/00000658-199303000-00006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE This study determined if the proposed mediators of splanchnic blood flow, prostacyclin and glucagon, were elevated in patients with portal hypertension undergoing portal systemic shunts. SUMMARY BACKGROUND DATA Chronic portal hypertension results in increased portal venous pressure and increased splanchnic blood flow. Animal studies have suggested prostacyclin or glucagon, potent vasodilators, as potential mediators of this increased flow. Correlative clinical studies have been difficult to perform due to the wide variation in degree of portal-systemic shunting and the frequent association of parenchymal liver disease in patients with cirrhosis. METHODS The authors measured portal and systemic hemodynamics in PGI2 and glucagon levels in patients with portal hypertension due to cirrhosis (partial portal systemic shunt) and Budd-Chiari syndrome (complete portal systemic shunt) undergoing portal systemic shunts and in porto normotensive patients undergoing exploratory laparotomies. RESULTS PGI2 levels in portal hypertension were significantly increased over normal, and prostacyclin in Budd-Chiari patients were increased significantly over patients with cirrhosis. Both PGI2 and portal venous pressure decreased significantly after portal systemic shunting, and prostacyclin levels correlated directly with portal venous pressure (R = 0.37, p < 0.05). CONCLUSIONS This is the first evidence in humans supporting the hypothesis that PGI2 is elevated in portal hypertension and is related to both the degree of portal venous obstruction and portal pressure. PGI2 probably has a role in the abnormal splanchnic hemodynamics of human portal hypertension.
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Affiliation(s)
- J V Sitzmann
- Johns Hopkins Medical Institutions, Baltimore, Maryland 21205
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Lin PW, Shan YS. Effects of splenectomy and splenic artery ligation on the portal pressure in portal hypertensive rats. J Surg Res 1992; 53:621-4. [PMID: 1494297 DOI: 10.1016/0022-4804(92)90264-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Immediate, short-, and long-term effects of splenectomy and splenic artery ligation on the portal pressure were studied in animal models experimentally created by partial portal vein ligation. The portal pressure of these animals would usually elevate immediately after partial ligation of the portal vein from a normal level of 6.0 +/- 0.5 to 14.8 +/- 1.3 mm Hg (P < 0.005), which could be maintained at least for 6 months. The portal pressure measured at 2 weeks, 4 weeks, and 6 months after portal vein ligation was 14.0 +/- 2.7, 15.2 +/- 2.7, and 12.7 +/- 2.0 mm Hg, respectively (P < 0.005, as compared with the normal). When splenectomy was performed on these animals at 2 weeks after partial portal vein ligation, the pressure dropped immediately but only transiently from 14.0 +/- 2.7 to 11.0 +/- 3.0 mm Hg, and bounced back to the presplenectomy level in 20 sec. After an additional 2 weeks, the portal pressure in these splenectomized rats was usually at 15.2 +/- 4.2 mm Hg, which was indistinguishable from that of rats whose portal vein was ligated but the spleen was not removed. Six months after splenectomy, however, the portal hypertensive rats had a portal pressure of 17.1 +/- 6.4 mm Hg, which was significantly higher than that of the controls. Splenic artery ligation, on the other hand, did not result in any immediate decrease in portal pressure (14.0 +/- 2.7 mm Hg vs 14.6 +/- 1.4 mm Hg; P > 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P W Lin
- Department of Surgery, Medical College, National Cheng Kung University, Tainan, Taiwan, Republic of China
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Coy DL, Mehta R, Zee P, Salchli F, Turek FW, Blei AT. Portal-systemic shunting and the disruption of circadian locomotor activity in the rat. Gastroenterology 1992; 103:222-8. [PMID: 1612329 DOI: 10.1016/0016-5085(92)91116-l] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To determine if the extent of portal-systemic shunting (PSS) influences the disruption of circadian function in chronic liver disease, locomotor activity was examined in two rat models with varying degrees of PSS, i.e., portal vein ligation (PVL) and end-to-side portacaval anastomosis (PCA). Animals were housed in individual activity cages under conditions of 12 hour light/12 hour darkness (weeks 0-3), then under conditions of constant dim light (weeks 4-7). Cages were equipped with running wheels connected to a continuous recorder, and daily tracings of running activity were recorded for 7 weeks. Computer analysis of wheel revolutions per hour with a chi 2 periodogram was used to calculate Qp, a measure of the amplitude of a circadian rhythm. The degree of PSS was measured by means of radioactive microspheres injected into the ileocolic vein and spleen. PVL rats were found to have PSS from the splenic and mesenteric territories of 88% and 27%, respectively; circadian periodicity was maintained in all PVL rats. PCA rats had complete shunting (greater than 99%) and showed a range of disrupted circadian rhythms from blunting of the amplitude to complete absence of the locomotor activity rhythm. This spectrum of disorganization occurred in spite of similar degrees of liver atrophy and weight gain. Whereas PCA in rats markedly disturbs the circadian rhythm of locomotor activity, animals with considerably less PSS from PVL exhibit normal behavior. The extent of PSS could be a variable affecting the expression of circadian rhythms in liver disease.
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Affiliation(s)
- D L Coy
- Department of Medicine, Lakeside Veterans Administration Medical Center, Chicago, Illinois
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Abstract
To explore a possible role for adenosine in the pathogenesis of the splanchnic hyperemia of cirrhosis, we administered 8-phenyltheophylline, a specific adenosine receptor antagonist, to rats with biliary cirrhosis caused by bile duct ligation and to control sham-operated rats. Micro-Doppler flow studies showed that a 10-mumol/kg dose of 8-phenyltheophylline completely abolished the superior mesenteric hyperemic response to infusions of exogenous adenosine in both cirrhotic and control rats. Analysis of regional blood flows by radioactive microspheres demonstrated that this dose of 8-phenyltheophylline in cirrhotic rats significantly increased portal tributary vascular resistance by 60% and decreased portal tributary blood flow by 26%. This decrease was entirely the result of a 42% reduction in the intestinal blood flow. 8-phenyltheophylline did not affect cardiac output, arterial pressure or any other extrasplanchnic hemodynamic variables in cirrhotic rats. No detectable effect of 8-phenyltheophylline was seen in sham-operated rats. These results suggest that adenosine may be involved in the genesis of splanchnic hyperemia in cirrhotic rats.
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Affiliation(s)
- S S Lee
- Gastroenterology Research Group, University of Calgary, Alberta, Canada
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Orrego H, Carmichael FJ. Effects of alcohol on liver haemodynamics in the presence and absence of liver disease. J Gastroenterol Hepatol 1992; 7:70-89. [PMID: 1543873 DOI: 10.1111/j.1440-1746.1992.tb00939.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- H Orrego
- Department of Medicine, University of Toronto, Ontario, Canada
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Stauber RE, Ruthardt FW, Tauxe WN, Van Thiel DH. Evaluation of portal-systemic shunting in rats from mesenteric and splenic beds. Dig Dis Sci 1991; 36:209-15. [PMID: 1988265 DOI: 10.1007/bf01300758] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In rats with partial portal vein ligation, 95 +/- 0.9% of the splenic blood flow is shunted from the portal to the systemic circulation when an intrasplenic injection of microspheres is used to determine the degree of shunting. Despite this magnitude of portal-systemic shunting, several biochemical and endocrine consequences of portal-systemic shunting occur at levels below what is expected for the degree of shunting found. In an effort to resolve these discordant findings, shunting from both the splenic and the mesenteric bed was studied in anesthetized portal hypertensive rats with various degrees and/or duration of portal vein stenosis. The shunting from the mesenteric bed averaged 66.7 +/- 29.9% (range 5.1-99.1%) and was influenced both by the degree and duration of portal vein stenosis. In contrast, shunting from the splenic bed averaged 97.3 +/- 4.0% (range 79-99.9%) and demonstrated no variation between groups determined by the degree of portal vein stenosis. The shunting from the splenic bed was consistently greater than that found from the mesenteric bed. Mesenteric but not splenic shunting correlated with serum bile acid levels. Mesenteric shunting was related inversely to the weight-adjusted liver mass and to serum testosterone levels. Based upon these data obtained in portal hypertensive rats, it is concluded that splenic injections of microspheres overestimate portal-systemic shunting. In contrast, mesenteric injections of microspheres yield values for shunting that correlate well with independently determined biochemical and endocrine consequences of shunting. These observations support the validity of the mesenteric shunting measurements obtained.
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Affiliation(s)
- R E Stauber
- Division of Gastroenterology (Medicine), University of Pittsburgh School of Medicine, Pennsylvania 15261
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Abstract
Hepatic, splanchnic, and systemic hemodynamic effects of somatostatin infusion, as well as changes in plasma glucagon concentration, were studied in normal rats, using techniques involving radioactive microspheres and radioimmunoassay. Somatostatin infusion caused a decrease in arterial blood flow to the stomach, small intestine and spleen, with the net effect of reducing hepatic portal blood flow and portal pressure. The hepatic arterial blood flow was not altered. The systemic hemodynamic effects of somatostatin were slight, although renal blood flow diminished, Plasma glucagon concentration did not vary immediately after somatostatin infusion. The mechanism of the hemodynamic action of the hormone is not yet clear, but in normal conditions it is not related to the inhibition of glucagon secretion.
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Mehta R, Gottstein J, Zeller WP, Lichtenberg R, Blei AT. Endotoxin and the hyperdynamic circulation of portal vein-ligated rats. Hepatology 1990; 12:1152-6. [PMID: 2227813 DOI: 10.1002/hep.1840120513] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Humoral factors may be responsible for the hyperdynamic circulation seen in portal hypertension. Endotoxin, a peripheral arteriolar vasodilator, has been proposed to mediate this hemodynamic picture. We examined the pathogenic role of endotoxin in portal vein-ligated rats, a prehepatic portal hypertensive model with a well-developed hyperdynamic circulation. To this end, we (a) administered oral neomycin, a poorly absorbable antibiotic, at doses of 50 and 100 mg/day for 7 days and found no evident splanchnic hemodynamic effects of a 2-log-fold reduction of cecal aerobic bacterial flora as assessed by the radioactive microsphere technique in portal vein-ligated rats studied in the postanesthesia awake state; (b) assayed endotoxin in arterial samples using a quantitative limulus assay and found no evidence of endotoxinemia in PVL rats; (c) induced a state of endotoxin tolerance by repeated daily intraperitoneal injections of low-dose endotoxin and found no amelioration of the hyperdynamic state in portal vein-ligated rats. Our results do not support the hypothesis that endotoxin plays a major pathogenic role in the hyperdynamic circulation of this experimental model.
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Affiliation(s)
- R Mehta
- Department of Medicine, Lakeside Veterans Administration Medical Center, Chicago, IL 60611
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