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Chen YS, Wen CK, Liu GH, Lee TY. Electroacupuncture attenuates vascular hyporeactivity in a rat model of portal hypertension induced by bile duct ligation. Acupunct Med 2021; 40:68-77. [PMID: 34553631 DOI: 10.1177/09645284211039230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND A hyperdynamic circulation and impaired vascular responsiveness to vasoconstrictors are observed in portal hypertension (PHT) rats. Inflammation is a major contributor to the hyperdynamic circulation state in murine models of PHT. Electroacupuncture (EA) may ameliorate the inflammatory response and limit arterial vasodilatation and portal pressure. This study investigated the possible mechanisms underlying putative hemodynamics effects of EA in normal and PHT rats. METHODS PHT was induced by bile duct ligation (BDL) surgery over 4 weeks in rats. Sham-operated and BDL rats were treated with low-frequency EA (2 Hz) at ST36 10 min three times weekly for one or two consecutive weeks (for a total of 3 or 7 treatments, respectively). Serum tumor necrosis factor-α (TNF-α), nitrite/nitrate (NOx) and 6-keto-prostaglandin F1α (6-keto-PGF1α) were analyzed, and hemodynamic variation and contractile responses to phorbol-12,13-dibutyrate and phenylephrine in aortic and superior mesenteric arterial rings were recorded. Inducible (i) and endothelial (3) nitric oxide synthase (NOS), cyclooxygenase-1 (COX-1), and protein kinase C-α (PKC-α) levels were determined by Western blotting. RESULTS EA significantly reduced portal pressure and serum TNF-α, NOx and 6-keto-PGF1α levels compared to the untreated BDL group, enhanced maximum contractile responses in the aorta, up-regulated PKC-α, and down-regulated iNOS and COX-1 levels. In addition, EA decreased the aortic angiogenesis signaling cascade, reflected by down-regulation of vascular endothelial growth factor (VEGF) abundance and transforming growth factor β receptor (TGFβR)I/II expression, as assessed by immunostaining. CONCLUSION EA attenuates TNF-α, NO and 6-keto-PGF1α overproduction, modulates the vascular levels of constitutive NOS and PKC-α, blunts the development of the angiogenesis cascade, and enhances vascular contractile force in PHT rats.
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Affiliation(s)
- Yu-Sheng Chen
- Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Division of Acupuncture and Moxibustion, Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.,Taiwan Huangdi-Neijing Medical Practice Association (THMPA), Taoyuan, Taiwan
| | - Chorng-Kai Wen
- School of Post-Baccalaureate Chinese Medicine, Tzu Chi University, Hualien, Taiwan
| | - Geng-Hao Liu
- Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Division of Acupuncture and Moxibustion, Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.,Taiwan Huangdi-Neijing Medical Practice Association (THMPA), Taoyuan, Taiwan.,School of Traditional Chinese Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tzung-Yan Lee
- Graduate Institute of Traditional Chinese Medicine, School of Chinese Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan
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Møller S, Kimer N, Barløse M, Bendtsen F. Pathophysiological-based treatments of complications of cirrhosis. Scand J Gastroenterol 2020; 55:383-394. [PMID: 32233873 DOI: 10.1080/00365521.2020.1744709] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Detailed knowledge and understanding of the pathophysiological mechanisms and changes in hepatic and splanchnic function leading to the development of haemodynamic changes and portal hypertension in patients with cirrhosis are essential since it guides the search for targets to ameliorate liver-related abnormalities. Recent research has focused on the gut-liver axis, changes in intestinal permeability, translocation of bacterial products, and inflammation as important drivers of haemodynamic alterations and thereby targets for treatment. Additionally, treatment strategies should focus on microbiotic modulation, antiangiogenics, anti-inflammatory strategies, and modulation of bile acid metabolism. This paper aims to review contemporary pathophysiological-based treatment principles of the major complications of cirrhosis and portal hypertension and future targets for treatment.
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Affiliation(s)
- Søren Møller
- Department Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark
| | - Nina Kimer
- Gastro Unit, Medical Division, Hvidovre Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Bridge Translational Excellence Programme, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Mads Barløse
- Department Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark
| | - Flemming Bendtsen
- Gastro Unit, Medical Division, Hvidovre Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Møller S, Bendtsen F. The pathophysiology of arterial vasodilatation and hyperdynamic circulation in cirrhosis. Liver Int 2018; 38:570-580. [PMID: 28921803 DOI: 10.1111/liv.13589] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/11/2017] [Indexed: 12/11/2022]
Abstract
Patients with cirrhosis and portal hypertension often develop complications from a variety of organ systems leading to a multiple organ failure. The combination of liver failure and portal hypertension results in a hyperdynamic circulatory state partly owing to simultaneous splanchnic and peripheral arterial vasodilatation. Increases in circulatory vasodilators are believed to be due to portosystemic shunting and bacterial translocation leading to redistribution of the blood volume with central hypovolemia. Portal hypertension per se and increased splanchnic blood flow are mainly responsible for the development and perpetuation of the hyperdynamic circulation and the associated changes in cardiovascular function with development of cirrhotic cardiomyopathy, autonomic dysfunction and renal dysfunction as part of a cardiorenal syndrome. Several of the cardiovascular changes are reversible after liver transplantation and point to the pathophysiological significance of portal hypertension. In this paper, we aimed to review current knowledge on the pathophysiology of arterial vasodilatation and the hyperdynamic circulation in cirrhosis.
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Affiliation(s)
- Søren Møller
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, University of Copenhagen, Copenhagen, Denmark
| | - Flemming Bendtsen
- Gastro Unit, Medical Division, Faculty of Health Sciences, Hvidovre Hospital, University of Copenhagen, Copenhagen, Denmark
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4
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5
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Lee JW. Renal dysfunction in patients with chronic liver disease. Electrolyte Blood Press 2009; 7:42-50. [PMID: 21468185 PMCID: PMC3041485 DOI: 10.5049/ebp.2009.7.2.42] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 11/23/2009] [Indexed: 12/13/2022] Open
Abstract
Renal dysfunction in patients with chronic liver disease encompasses a clinical spectrum of hyponatremia, ascites, and hepatorenal syndrome. Clinical observation has suggested that patients with cirrhosis have hyperdynamic circulation, and recent studies strongly suggest that peripheral arterial vasodilatation and subsequent development of hyperdynamic circulation are responsible for disturbances in renal function. Arterial vasodilatation predominantly occurs in the splanchnic vascular bed, and seems to precede an increase in blood flow in the splanchnic circulation. Nitric oxide plays a central role in progressive vasodilatation, as evidenced by in vivo and in vitro studies. Renal dysfunction negatively affects the prognosis of patients with cirrhosis, as hyponatremia, ascites, and azotemia are associated with increased rate of complications and mortality. Recent advances in understanding the pathophysiology of renal dysfunction have enabled clinicians to develop new diagnostic criteria and therapeutic recommendations. Hepatorenal syndrome is regarded as a potentially reversible disorder, as systemic vasoconstrictors with concomitant albumin administration are emerging as a promising management option, especially in terms of providing bridging therapy for patients awaiting liver transplantation.
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Affiliation(s)
- Jay Wook Lee
- Division of Nephrology, Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea
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6
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Agouni A, Lagrue-Lak-Hal AH, Ducluzeau PH, Mostefai HA, Draunet-Busson C, Leftheriotis G, Heymes C, Martinez MC, Andriantsitohaina R. Endothelial dysfunction caused by circulating microparticles from patients with metabolic syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1210-9. [PMID: 18772329 DOI: 10.2353/ajpath.2008.080228] [Citation(s) in RCA: 218] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Microparticles are membrane vesicles that are released during cell activation and apoptosis. Elevated levels of microparticles occur in many cardiovascular diseases; therefore, we characterized circulating microparticles from both metabolic syndrome (MS) patients and healthy patients. We evaluated microparticle effects on endothelial function; however, links between circulating microparticles and endothelial dysfunction have not yet been demonstrated. Circulating microparticles and their cellular origins were examined by flow cytometry of blood samples from patients and healthy subjects. Microparticles were used either to treat human endothelial cells in vitro or to assess endothelium function in mice after intravenous injection. MS patients had increased circulating levels of microparticles compared with healthy patients, including microparticles from platelet, endothelial, erythrocyte, and procoagulant origins. In vitro treatment of endothelial cells with microparticles from MS patients reduced both nitric oxide (NO) and superoxide anion production, resulting in protein tyrosine nitration. These effects were associated with enhanced phosphorylation of endothelial NO synthase at the site of inhibition. The reduction of O2(-) was linked to both reduced expression of p47 phox of NADPH oxidase and overexpression of extracellular superoxide dismutase. The decrease in NO production was triggered by nonplatelet-derived microparticles. In vivo injection of MS microparticles into mice impaired endothelium-dependent relaxation and decreased endothelial NO synthase expression. These data provide evidence that circulating microparticles from MS patients influence endothelial dysfunction.
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Affiliation(s)
- Abdelali Agouni
- INSERM U771, Centre National de la Recherche Scientifique Unité Mixte de Recherche, 6214, the Université d'Angers, Angers, France
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7
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Colle I, Geerts AM, Van Steenkiste C, Van Vlierberghe H. Hemodynamic changes in splanchnic blood vessels in portal hypertension. Anat Rec (Hoboken) 2008; 291:699-713. [PMID: 18484617 DOI: 10.1002/ar.20667] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Portal hypertension (PHT) is associated with a hyperdynamic state characterized by a high cardiac output, increased total blood volume, and a decreased splanchnic vascular resistance. This splanchnic vasodilation is a result of an important increase in local and systemic vasodilators (nitric oxide, carbon monoxide, prostacyclin, endocannabinoids, and so on), the presence of a splanchnic vascular hyporesponsiveness toward vasoconstrictors, and the development of mesenteric angiogenesis. All these mechanisms will be discussed in this review. To decompress the portal circulation in PHT, portosystemic collaterals will develop. The presence of these portosystemic shunts are responsible for major complications of PHT, namely bleeding from gastrointestinal varices, encephalopathy, and sepsis. Until recently, it was accepted that the formation of collaterals was due to opening of preexisting vascular channels, however, recent data suggest also the role of vascular remodeling and angiogenesis. These points are also discussed in detail.
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Affiliation(s)
- Isabelle Colle
- Department of Hepatology and Gastroenterology, Ghent University Hospital, Ghent, Belgium.
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8
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Mostefai HA, Agouni A, Carusio N, Mastronardi ML, Heymes C, Henrion D, Andriantsitohaina R, Martinez MC. Phosphatidylinositol 3-kinase and xanthine oxidase regulate nitric oxide and reactive oxygen species productions by apoptotic lymphocyte microparticles in endothelial cells. THE JOURNAL OF IMMUNOLOGY 2008; 180:5028-35. [PMID: 18354228 DOI: 10.4049/jimmunol.180.7.5028] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Microparticles (MPs) are membrane vesicles released during cell activation and apoptosis. We have previously shown that MPs from apoptotic T cells induce endothelial dysfunction, but the mechanisms implicated are not completely elucidated. In this study, we dissect the pathways involved in endothelial cells with respect to both NO and reactive oxygen species (ROS). Incubation of endothelial cells with MPs decreased NO production that was associated with overexpression and phosphorylation of endothelial NO synthase (eNOS). Also, MPs enhanced expression of caveolin-1 and decreased its phosphorylation. Microparticles enhanced ROS by a mechanism sensitive to xanthine oxidase and P-IkappaBalpha inhibitors. PI3K inhibition reduced the effects of MPs on eNOS, but not on caveolin-1, whereas it enhanced the effects of MPs on ROS production. Microparticles stimulated ERK1/2 phosphorylation via a PI3K-depedent mechanism. Inhibition of MEK reversed eNOS phosphorylation but had no effect on ROS production induced by MPs. In vivo injection of MPs in mice impaired endothelial function. In summary, MPs activate pathways related to NO and ROS productions through PI3K, xanthine oxidase, and NF-kappaB pathways. These data underscore the pleiotropic effects of MPs on NO and ROS, leading to an increase oxidative stress that may account for the deleterious effects of MPs on endothelial function.
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Affiliation(s)
- H Ahmed Mostefai
- Centre National de la Recherche Scientifique Unité Mixte de Recherche 6214, INSERM Unité 771, and Université d'Angers, Angers, France
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9
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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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10
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Abstract
Portal hypertension is a complication of diseases that obstruct portal blood flow, such as cirrhosis or portal vein thrombosis. In these diseases, increased vascular resistance to portal blood flow is the primary mechanism that increases portal pressure. In cirrhosis, increased intrahepatic vascular resistance is a result of both intrahepatic vasoconstriction and surrounding mechanical factors including collagen deposition and regenerative nodules. This article summarizes recent progress in the understanding of molecular mechanisms underlying the portal hypertension-associated arterial alterations in splanchnic systemic territories and those involved in the development of portal-systemic collateral circulation.
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Affiliation(s)
- Richard Moreau
- INSERM, U773, Centre de Recherche Biomédicale Bichat-Beaujon CRB3, Hôpital Beaujon, Clichy 92118, France.
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11
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Frossard JL, Quadri R, Hadengue A, Morel P, Pastor CM. Endothelial nitric oxide synthase regulation is altered in pancreas from cirrhotic rats. World J Gastroenterol 2006; 12:228-33. [PMID: 16482622 PMCID: PMC4066031 DOI: 10.3748/wjg.v12.i2.228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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 determine whether biliary cirrhosis could induce pancreatic dysfunction such as modifications in endothelial nitric oxide synthase(eNOS) expression and whether the regulation of eNOS could be altered by the regulatory proteins caveolin and heat shock protein 90 (Hsp90), as well as by the modifications of calmodulin binding to eNOS.
METHODS: Immunoprecipitations and Western blotting analysis were performed in pancreas isolated from sham and cirrhotic rats.
RESULTS: Pancreatic injury was minor in cirrhotic rats but eNOS expression importantly decreased with the length (and the severity) of the disease. Because co-immunoprecipitation of eNOS with both Hsp90 and caveolin similarly decreased in cirrhotic rats, eNOS activity was not modified by this mechanism. In contrast, cirrhosis decreased the calmodulin binding to eNOS with a concomitant decrease in eNOS activity.
CONCLUSION: In biliary cirrhosis, pancreatic injury is minor but the pancreatic nitric oxide (NO) production is significantly decreased by two mechanisms: a decreased expression of the enzyme and a decreased binding of calmodulin to eNOS.
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Affiliation(s)
- Jean-Louis Frossard
- Division de Gastroenterologie, Hôpitaux Universitaires de GenevePhilippe Morel, Departement de Chirurgie, Hopitaux Universitaires de Geneve, Switzerland
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12
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Lin HC, Yang YY, Huang YT, Lee TY, Hou MC, Lee FY, Lee SD. Vascular contractile response and signal transduction in endothelium-denuded aorta from cirrhotic rats. World J Gastroenterol 2005; 11:2306-12. [PMID: 15818743 PMCID: PMC4305816 DOI: 10.3748/wjg.v11.i15.2306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [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: The mechanism of decreased vascular reactivity to vasoconstrictors in portal hypertension is still unclear. In addition to nitric oxide, defects in post-receptor signal transduction pathway have been suggested to play a role. However, substantial evidences observed equivocal changes of vascular reactivity following different agonists that challenged the hypothesis of the post-receptor defect. The current study was to evaluate the vascular reactivity to different agonists and the inositol trisphosphate (IP3) changes in signal transduction cascade from cirrhotic rats with portal hypertension.
METHODS: The endothelial denuded aortic rings from cirrhotic and sham-operated rats were obtained for ex vivo tension study and measurement of the corresponding [3H] IP3 formation following different receptor and nonreceptor-mediated agonists’ stimulation. Additionally, iNOS protein expression was measured in thoracic aorta. The contractile response curves to phenylephrine were performed in endothelial denuded aortic rings with and without preincubation with a specific iNOS inhibitor (L-N(6)-(1-iminoethyl)-lysine, L-NIL).
RESULTS: In endothelial denuded aortic rings of cirrhotic rats, the vascular responses were reduced with phenylephrine and arginine vasopressin (AVP) stimulation but were normal with U-46619, NaF/AlCl3, and phorbol esterdibutyrate (PdBU) stimulation. Compared to the corresponding control groups, the degree of the increment of [3H] IP3 formation from basal level was also decreased with phenylephrine and AVP stimulation, but was normal with U-46619 and NaF/AlCl3 stimulation. The preincubation with L-NIL did not modify the hyporesponsiveness to phenylephrine. Additionally, the iNOS protein expression in thoracic aorta was not different in cirrhotic and sham-operated rats.
CONCLUSION: Without the influence of nitric oxide, vascular hyporeactivity to vasoconstrictors persisted in cirrhotic rats with portal hypertension. However, the decreased vascular reactivity is an agonist-specific phenomenon. In addition, G-protein and phospholipase C pathway associated with the IP3 productions may be intact in cirrhotic rats with portal hypertension.
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Affiliation(s)
- Han-Chieh Lin
- Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 11217, Taiwan, China.
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13
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Tazi KA, Barrière E, Moreau R, Poirel O, Lebrec D. Relationship between protein kinase C alterations and nitric oxide overproduction in cirrhotic rat aortas. LIVER 2002; 22:178-83. [PMID: 12028414 DOI: 10.1034/j.1600-0676.2002.01616.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Although nitric oxide (NO) overproduction and protein kinase C (PKC) alterations may play a role in systemic haemodynamic changes in cirrhotic rat aortas, the relationship between NO synthase (NOS) hyperactivation and PKC hypoactivation is unknown. Therefore, the relationships between NOS and PKC activities were studied in cirrhotic rat aortas. METHODS The effects of NOS inhibition by Nw-nitro-L-arginine (LNNA) on the contractile response to phorbol myristate acetate (PMA), a PKC activator, were studied. The effects of NOS inhibition and those of S-nitroso-N acetyl-DL-penicillamine (SNAP), an NO donor, on PKC activity were also evaluated. The effects of PKC activation and inhibition on total NOS and inducible NOS (iNOS) activities were measured. Nitric oxide synthase inhibition caused an increase in PMA-induced contraction and an increase in PKC activity in cirrhotic rat aortas. S-nitroso-N acetyl-DL-penicillamine induced downregulation of PKC activity. Total basal aortic NOS activity was significantly higher in cirrhotic rats than in control rats and activation of PKC by PMA induced a decrease in total aortic NOS activity. Protein kinase C downregulation caused an increase in both total aortic NOS and iNOS activities only in control rats, whereas only iNOS activity increased in cirrhotic rats. CONCLUSION In cirrhotic rat aortas, NO overproduction plays a role in the decreased PKC activation that leads to reduced aortic contraction. Overactivation of aortic NOS in cirrhotic rats may be because of, in part, the reduced PKC activity.
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MESH Headings
- Animals
- Aorta, Thoracic/metabolism
- Down-Regulation
- Enzyme Inhibitors/pharmacology
- In Vitro Techniques
- Liver Cirrhosis, Biliary/etiology
- Liver Cirrhosis, Biliary/metabolism
- Liver Cirrhosis, Experimental/etiology
- Liver Cirrhosis, Experimental/metabolism
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide Donors/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase Type II
- Penicillamine/analogs & derivatives
- Penicillamine/pharmacology
- Protein Kinase C/metabolism
- Rats
- Rats, Sprague-Dawley
- Tetradecanoylphorbol Acetate/pharmacology
- omega-N-Methylarginine/pharmacology
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Affiliation(s)
- Khalid A Tazi
- Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM U-481, Hôpital Beaujon, Clichy, France.
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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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15
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Abstract
Portal hypertension is defined by an elevation in portal pressure and is associated with haemodynamic alterations. Haemodynamic changes are characterized by a hyperdynamic circulation in the splanchnic and systemic territories and a reduced pressure effect of vasoconstrictive substances. They were observed in both patients and animals with different types of portal hypertension. In this review, the main results and their mechanisms of the splanchnic and systemic haemodynamic alterations in portal hypertension are discussed.
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Affiliation(s)
- D Lebrec
- Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM U-481, Hôpital Beaujon, Clichy, France.
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16
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Abstract
Abnormal vascular responsiveness to ligands has been frequently observed in cirrhosis and portal hypertension, but its existence is not proven. The signaling pathways in vascular smooth muscle cells (VSMCs) have been studied only in animal models of cirrhosis and portal hypertension. Emerging evidence suggests that active relaxation, expressed as augmented content or activity of effectors within the cyclic AMP signaling pathway and suppressed content or activity of effectors in the inositol 1,4,5-trisphosphate/1,2-diacylglycerol signaling pathway, may be occurring in VSMCs of the splanchnic circulation in portal hypertension. The evidence supporting the existence of this phenomenon in the VSMCs of extrasplanchnic circulations in portal hypertension, as well as in the splanchnic circulation when chronic cellular damage is present, is very limited. The status of the other signaling pathways associated with contractile functions of the VSMCs, viz., cyclic GMP and tyrosine kinase-linked pathways, is unknown. The status of all the signaling pathways in non-contractile functions of VSMCs, such as growth and remodeling, has not been studied. As our overall understanding on the signaling pathways in VSMCs is only emerging, it is premature to implicate altered activity of the signaling pathways as the underlying basis of vascular hyporesponsiveness in cirrhosis and portal hypertension, and to extrapolate these limited observations to the human condition.
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MESH Headings
- Animals
- Cells, Cultured
- Cyclic AMP/metabolism
- Cyclic GMP/metabolism
- Disease Models, Animal
- Hypertension, Portal/physiopathology
- In Vitro Techniques
- Liver/blood supply
- Liver/physiopathology
- Liver Cirrhosis/physiopathology
- Models, Chemical
- Muscle Development
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/physiology
- Phosphatidylinositols/metabolism
- Protein Kinases/metabolism
- Receptors, Cell Surface/agonists
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/metabolism
- Signal Transduction/physiology
- Splanchnic Circulation/physiology
- Vasoconstriction/physiology
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Affiliation(s)
- A Bomzon
- Department of Pharmacology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, P.O. Box 9649, Haifa 31096, Israel.
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Suenaga H, Kasuya Y, Kamata K. Effects of calmodulin antagonist (W-7) on phorbol ester (PMA)-induced contractile response in isolated rat aorta. J Smooth Muscle Res 2001; 37:1-7. [PMID: 11436980 DOI: 10.1540/jsmr.37.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to investigate effects of calmodulin antagonist (W-7) on the contractile response of the rat aorta induced by activation of protein kinase C (PKC) by phorbol ester. Phorbol 12-myristate 13-acetate (PMA) produced biphasic contraction i.e., a sustained contraction (initial contraction) and 17.9 +/- 1.7 min later, this progressively developed contraction was changed to a delayed contraction superimposed on the initial contraction. The delayed contraction was completely inhibited by treatment with nicardipine. The onset of the delayed contraction was significantly delayed by treatment with W-7, whereas same concentration of W-7 showed a weak relaxant effect (10%) on the PMA-induced maximal contraction of aorta. Higher concentration of W-7 strongly inhibited PMA-induced sustained contraction. These results suggest that PMA-induced biphasic contractile response may be regulated by calmodulin.
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Affiliation(s)
- H Suenaga
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
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