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Abstract
BACKGROUND Prostacyclin has been shown to increase portal hypertension, but the mechanism is unclear. This study aimed to investigate whether the overproduction of prostacyclin (PGI2) in cirrhosis participates in the splanchnic vascular hyporesponsiveness to vasoconstrictors in cirrhotic rats. METHODS Cirrhotic model was created by subcutaneous injection of 60% carbon tetrachloride (CCl4) corn oil solution combined with intermittent drinking of 5% alcohol, and age-matched rats served as controls. The isolated third-generation mesenteric arterioles were used to examine the contractile response to norepinephrine. The changes in vascular diameter were observed under a microscope imaging device. The plasma concentration of 6-ketone-prostaglandin F1alpha (6-keto-PGF1alpha, a stable metabolite of PGI2) was tested via enzyme immunoassays and the expression of cyclooxygenase (COX) in mesenteric arteries was detected by Western blotting. RESULTS In parallel with the increase of plasma 6-keto-PGF1alpha, the contractile response of arterioles from cirrhotic rats to norepinephrine was significantly impaired compared with that from controls. Inhibition of PGI2 or protein kinase A with indomethacin or Rp-adenosine 3', 5'-cyclic monophosphothioate (Rp-cAMPS) partially reversed the vascular hypo-contractile response to norepinephrine in arterioles from cirrhotic rats. Indomethacin significantly decreased the plasma 6-keto-PGF1alpha. Furthermore, indomethacin significantly attenuated the effect of Rp-cAMPS on arterioles from cirrhotic rats. COX-1 expression was up-regulated in mesenteric arteries from cirrhotic rats, whereas COX-2 was not detectable in the mesenteric arteries from both cirrhotic and control rats. CONCLUSION Enhanced COX-1 expression in cirrhotic rats resulted in elevated PGI2 production which partially contributed to the splanchnic vascular hyporesponsiveness to a vasoconstrictor via the protein kinase A pathway.
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Dietrich P, Moleda L, Kees F, Müller M, Straub RH, Hellerbrand C, Wiest R. Dysbalance in sympathetic neurotransmitter release and action in cirrhotic rats: impact of exogenous neuropeptide Y. J Hepatol 2013; 58:254-61. [PMID: 23041305 DOI: 10.1016/j.jhep.2012.09.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/24/2012] [Accepted: 09/25/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Splanchnic vasodilation is an essential disturbance in portal hypertension. Increased systemic sympathetic nerve activity is well known, but potential corresponding vascular desensitization is incompletely characterized. Release of splanchnic sympathetic neurotransmitters noradrenaline (NA) and co-transmitter neuropeptide Y (NPY) remains to be elucidated. Finally, the effects of exogenous NPY on these mechanisms are unexplored. METHODS Portal vein ligated cirrhotic, and control rats were used for in vitro perfusion of mesenteric arteries. Depletion of vascular pressure response was induced by repetitive electric sympathetic perivascular nerve stimulation (PNS) and performed in the absence and presence of exogenous NPY. Additionally, PNS-induced release of NA and NPY was measured. RESULTS Mesenteric PNS-induced pressure response was lower in portal hypertension. Depletion of the pressure response to PNS, representing the degree of desensitization, was enhanced in portal hypertension. NA release was elevated, whereas NPY release was attenuated in cirrhosis. Administration of exogenous NPY led to marked recovery from desensitization and vasoconstrictive improvement in cirrhotic rats, being associated with more pronounced decrease of NA release. CONCLUSIONS Pronounced depletion of splanchnic arterial pressure-response to repetitive sympathetic nerve stimulation in cirrhosis is partly attributable to altered NA release as well as to deficient NPY release. External NPY restores vascular contractility and attenuates pathologically elevated NA release in the portal hypertensive mesenteric vasculature, revealing post-, and prejunctional effects at the vascular smooth muscle motor endplate; therefore outlining encouraging therapeutic strategies.
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Affiliation(s)
- P Dietrich
- Dept. Internal Medicine, University Medical Center, Regensburg 93042, Germany
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Wang GJ, Lin YL, Chen CH, Wu XC, Liao JF, Ren J. Cellular calcium regulatory machinery of vasorelaxation elicited by petasin. Clin Exp Pharmacol Physiol 2010; 37:309-15. [DOI: 10.1111/j.1440-1681.2009.05283.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Chen X, Pavlish K, Zhang HY, Benoit JN. Effects of chronic portal hypertension on agonist-induced actin polymerization in small mesenteric arteries. Am J Physiol Heart Circ Physiol 2006; 290:H1915-21. [PMID: 16339838 DOI: 10.1152/ajpheart.00643.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ability of arterial smooth muscle to respond to vasoconstrictor stimuli is reduced in chronic portal hypertension (PHT). Additional evidence supports the existence of a postreceptor defect in vascular smooth muscle excitation contraction coupling. However, the nature of this defect is unclear. Recent studies have shown that vasoconstrictor stimuli induce actin polymerization in smooth muscle and that the associated increase in F-actin is necessary for force development. In the present study we have tested the hypothesis that impaired actin polymerization contributes to reduced vasoconstrictor function in small mesenteric arteries derived from rats with chronic prehepatic PHT. In vitro studies were conducted on small mesenteric artery vessel rings isolated from normal and PHT rats. Isometric tension responses to incremental concentrations of phenylephrine were significantly reduced in PHT arteries. The ability to polymerize actin in portal hypertensive mesenteric arteries stimulated by phenylephrine was attenuated compared with control. Inhibition of cAMP-dependent protein kinase (PKA) restored agonist-induced actin polymerization of arteries from PHT rats to normal levels. Depolymerization of actin in arteries from normal rats reduced maximal contractile force but not myosin phosphorylation, suggesting a key role for the dynamic regulation of actin polymerization in the maintenance of vascular smooth muscle contraction. We conclude that reductions in agonist-induced maximal force development of PHT vascular smooth muscle is due, in part, to impaired actin polymerization, and prolonged PKA activation may underlie these changes.
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Affiliation(s)
- Xuesong Chen
- Deparment of Pharmacology, Physiology, and Therapeutics, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
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Lin HC, Huang YT, Wei HC, Yang YY, Lee TY, Wang YW, Hou MC, Lee SD. Hemodynamic effects of one week of carvedilol administration on cirrhotic rats. J Gastroenterol 2006; 41:361-8. [PMID: 16741616 DOI: 10.1007/s00535-006-1782-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 01/24/2006] [Indexed: 02/04/2023]
Abstract
BACKGROUND Carvedilol is a nonselective beta-blocker with alpha(1)-adrenergic blocking activity. It has been shown to decrease portal pressure in cirrhotic patients. The current study was undertaken to evaluate the possible mechanism of carvedilol on hemodynamics in cirrhotic rats with portal hypertension produced by common bile duct ligation. METHODS Male Sprague-Dawley rats received either a sham operation or common bile duct ligation. Three weeks after surgery, both sham-operated and cirrhotic rats were randomly assigned to receive vehicle or carvedilol 5 mg.kg(-1).12 h(-1) by gastric gavage for 1 week. Hemodynamic measurements, serum biochemistry, serum nitrate/nitrite and 6-keto-PGF(1alpha) levels, and aortic mRNA expression of eNOS and COX-1 were performed on the eighth day after drug administration. RESULTS Carvedilol treatment did not affect serum biochemistry in either sham-operated or cirrhotic rats. In sham-operated rats, administration of carvedilol significantly decreased the heart rate without affecting other hemodynamic values. In contrast, in cirrhotic rats, administration of carvedilol significantly decreased the cardiac index, portal pressure, heart rate, and portal territory blood flow, and it significantly increased systemic and portal territory vascular resistances. The hepatocollateral resistance was significantly decreased, but the hepatic arterial blood showed no significant changes. In sham-operated rats treated with carvedilol, serum nitrate/nitrite and 6-keto-PGF(1alpha) levels were not affected. In contrast, cirrhotic rats receiving carvedilol showed a significant decrease in serum nitrate/nitrite and 6-keto-PGF(1alpha) levels, associated with a decrease in aortic mRNA expression of eNOS and COX-1 compared with those receiving vehicle. CONCLUSIONS Carvedilol decreased portal pressure through a reduction of splanchnic blood flow associated with a decrease in hepatocollateral resistance. Additionally, administration of carvedilol decreased endothelial-related vasodilatory activities.
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Affiliation(s)
- Han-Chieh Lin
- Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taipei 11217, Taiwan
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Hennenberg M, Biecker E, Trebicka J, Jochem K, Zhou Q, Schmidt M, Jakobs KH, Sauerbruch T, Heller J. Defective RhoA/Rho-kinase signaling contributes to vascular hypocontractility and vasodilation in cirrhotic rats. Gastroenterology 2006; 130:838-54. [PMID: 16530523 DOI: 10.1053/j.gastro.2005.11.029] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 11/16/2005] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Portal hypertension is associated with arterial hypotension and vascular hypocontractility, which persists despite elevated plasma levels of vasoconstrictors. We investigated the role of the RhoA/Rho-kinase pathway in vascular smooth muscle hypocontractility of rats with secondary biliary cirrhosis. METHODS Aortic expressions of RhoA and Rho-kinase were analyzed in sham-operated and BDL rats by reverse-transcription polymerase chain reaction (RT-PCR) and immunoblots. Activation of aortic RhoA was examined by pull down of guanosine triphosphate (GTP)-RhoA and membrane translocation of RhoA. Rho-kinase activity was assessed as phosphorylation of its substrate, moesin. Contractility of isolated aortic rings was determined myographically. The hemodynamic effect of the Rho-kinase inhibitor (R)-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide (Y-27632) was determined in vivo by measuring changes in mean arterial pressure and systemic vascular resistance (SVR) (microspheres). RESULTS Contraction of aortic rings from BDL rats was impaired in response to the alpha(1)-adrenergic receptor agonist methoxamine but not to high molar KCl. Aortic expression of RhoA was unchanged in cirrhotic rats, whereas Rho-kinase was down-regulated posttranscriptionally. Methoxamine-induced activation of RhoA as well as basal and methoxamine-induced phosphorylation of moesin were strongly reduced in aortas from cirrhotic rats. Aortic rings from cirrhotic rats precontracted with methoxamine showed an increased sensitivity to relaxation with Y-27632. The drop in SVR induced by Y-27632 was larger in cirrhotic rats than in sham-operated rats. CONCLUSIONS An impaired vascular activation of RhoA and a down-regulation of Rho-kinase might contribute to vasodilation and vascular hypocontractility in BDL-induced cirrhosis.
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Affiliation(s)
- Martin Hennenberg
- Department of Internal Medicine I, University of Bonn, Bonn, Germany
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Atucha NM, Nadal FJA, Alcaraz A, Iyú D, Ortiz MC, García-Estañ J. Reduced capacitative calcium entry in the mesenteric vascular bed of bile duct-ligated rats. Eur J Pharmacol 2005; 525:117-22. [PMID: 16266702 DOI: 10.1016/j.ejphar.2005.09.046] [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] [Received: 02/03/2005] [Revised: 09/20/2005] [Accepted: 09/27/2005] [Indexed: 11/20/2022]
Abstract
In this work, we analyzed the interaction of nitric oxide (NO) with some of the mechanisms known to regulate intracellular calcium levels in order to gain insight into the mechanisms responsible for the reduced vascular pressor response to vasoconstrictors observed in an experimental model of liver cirrhosis. Specifically, we hypothesized that the entry of calcium through capacitative channels is defective in this model. The experiments were performed with isolated, Krebs-perfused and de-endothelialized mesenteric arterial bed of rats with bile duct ligation (4 weeks) and their controls. Pretreatment with thapsigargin to inhibit calcium uptake into sarcoplasmic reticulum potentiated the pressor responses to methoxamine, but the response of the cirrhotic vessels was significantly lower than that of the controls. Under the same conditions, perfusion of the mesenteries with zero calcium-Krebs resulted in lower pressor responses to methoxamine, especially in the mesenteries of the bile duct-ligated rats. To specifically analyze the entry of calcium through store-operated calcium channels, the pressor response to the addition of calcium was studied in mesenteries perfused with zero calcium-Krebs and in the presence of thapsigargin. Again, the response of the cirrhotic mesenteric beds was significantly lower than that of the control vessels. Under all these experimental conditions, the differences between control and cirrhotic responses were abolished by pretreatment with the NO synthesis inhibitor N(w)-nitro-L-arginine (NNA). These results indicate that, in the mesenteric bed of bile duct-ligated rats, an excess of nitric oxide interferes with the release of calcium from thapsigargin-sensitive internal stores and also reduces the capacitative entry of calcium into vascular muscular cells induced by the depletion of calcium from internal stores. This mechanism may have an important role in the reduced pressor response observed in the mesenteric vascular bed in cirrhosis.
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Affiliation(s)
- Noemí M Atucha
- Departamento de Fisiología, Facultad de Medicina, 30100 Murcia, Spain
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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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Vashist Y, Semela D, Dufour JF. Hyperdynamic circulation in liver cirrhosis: desensitization of vasoconstrictive receptors by G protein-coupled receptor kinases. Med Hypotheses 2004; 62:82-5. [PMID: 14729009 DOI: 10.1016/s0306-9877(03)00311-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Liver cirrhosis is complicated by a hyperdynamic circulation characterized by a generalized arterial vasodilatation. This vasodilatation occurs despite high plasma concentration of several potent vasoconstrictive substances like angiotensin, vasopressin, endothelin and norepinephrine. The experimental evidence available shows that compensatory adrenergic and vasoconstrictive signals are not normally transmitted intracellularly. G protein-coupled receptor kinases phosporylate plasma membrane receptors and block the transmission of the signal intracellularly. We hypothesize that these kinases are responsible for the desensitization to vasoconstrictors observed in patients with liver cirrhosis. Pharmacological intervention at this level might be beneficial to treat complications like ascites and variceal bleeding.
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Affiliation(s)
- Yogesh Vashist
- Department of Clinical Pharmacology, University of Bern, Murtenstrasse 35, Bern 3010, Switzerland
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Wang GJ, Liao JF, Hintz KK, Chen WP, Su MJ, Lin YL, Shi CC, Chen CF, Ren J. Calcium-antagonizing activity of S-petasin, a hypotensive sesquiterpene from Petasites formosanus, on inotropic and chronotropic responses in isolated rat atria and cardiac myocytes. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2004; 369:322-9. [PMID: 15010899 DOI: 10.1007/s00210-003-0863-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Accepted: 12/17/2003] [Indexed: 11/26/2022]
Abstract
Petasites formosanus, an indigenous species of Petasites, has been used to treat cardiovascular diseases such as hypertension for years. We have suggested recently that S-petasin, a major sesquiterpene from P. formosanus, inhibits vascular smooth muscle contraction through inhibition of voltage-dependent Ca(2+) channels, a phenomenon possibly responsible for the hypotensive effect of P. formosanus. This study was designed to examine the chronotropic and inotropic actions of S-petasin in the heart in vivo and in vitro. Administration of S-petasin (0.1-1.5 mg/kg i.v.) in anesthetized rats reduced heart rate dose-dependently. This response was consistent with significant suppression of both contractile amplitude and spontaneous firing rate of isolated atria, responses that were not antagonized by atropine (1 microM). Mechanical evaluation in isolated ventricular myocytes showed that S-petasin (0.1 to 100 microM) depressed peak myocyte contraction and intracellular Ca(2+) transients concentration-dependently. The duration of myocyte contraction was not affected. Whole-cell voltage clamp analysis revealed that S-petasin inhibited the L-type Ca(2+) current ( I(Ca,L)) concentration-dependently and shifted the steady-state inactivation curve of I(Ca,L) to more negative potentials. However, a receptor-binding assay failed to identify any significant interaction between S-petasin (0.1-300 microM) and the dihydropyridine binding sites of L-type voltage-dependent Ca(2+) channels. Taken together, these data show that the negative chronotropic and inotropic properties of S-petasin that can be ascribed mainly to I(Ca,L) inhibition, but not to blockade of dihydropyridine binding sites of L-type Ca(2+) channel or to muscarinic receptor activation.
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Affiliation(s)
- Guei-Jane Wang
- National Research Institute of Chinese Medicine, Taipei, Taiwan, Republic of China
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Colle IO, De Vriese AS, Van Vlierberghe HR, Lameire NH, De Vos MM. Vascular hyporesponsiveness in the mesenteric artery of anaesthetized rats with cirrhosis and portal hypertension: an in-vivo study. Eur J Gastroenterol Hepatol 2004; 16:139-45. [PMID: 15075986 DOI: 10.1097/00042737-200402000-00004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Cirrhosis is complicated by splanchnic vasodilation. Nitric oxide (NO) and prostacyclin contribute to this. Vascular hyporesponsiveness has been reported, but the underlying pathophysiological mechanisms are unclear. OBJECTIVE This in-vivo study examined the contribution of NO and prostacyclin to the development of vascular hyporesponsiveness in the mesenteric circulation of animals with cirrhosis and portal hypertension. METHODS Rats underwent common bile duct ligation (CBDL) (n = 11), partial portal vein ligation (PPVL) (n = 12) and sham-operation (sham) (n = 11). Blood flow in the mesenteric artery (MBF) was measured during intramesenteric infusion of endothelium-dependent (acetylcholine) and endothelium-independent vasodilators (deta-NONOate, pinacidil) and a vasoconstrictor (L-phenylephrine). The measurements were repeated after systemic infusion of L-NAME (NO synthase inhibition) and indomethacin (cyclo-oxygenase inhibition). RESULTS The MBF response to acetylcholine was significantly lower in CBDL and tended to be lower in PPVL than in sham. L-NAME and indomethacin significantly decreased the MBF response to acetylcholine in all groups. The hyporeactivity to acetylcholine in CBDL and PPVL was maintained after L-NAME and indomethacin. The MBF response to pinacidil, deta-NONOate and phenylephrine, before and after NO synthase and cyclo-oxygenase inhibition, was lower in CBDL and PPVL than in sham. CONCLUSION This is the first in-vivo study demonstrating an impaired response to endothelium-dependent and endothelium-independent vasodilators as well as vasoconstrictors in the mesenteric artery of animals with cirrhosis and portal hypertension. The generalised hyporeactivity suggests an abnormality on the vascular smooth muscle cell level. The hyporesponsiveness persisted after combined NO synthase and cyclo-oxygenase inhibition.
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Affiliation(s)
- Isabelle O Colle
- Division of Hepato-Gastroenterology, Department of Medicine, Ghent University Hospital, Belgium.
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12
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Yang YY, Lin HC, Huang YT, Lee TY, Hou MC, Lee FY, Liu RS, Chang FY, Lee SD. Effect of 1-week losartan administration on bile duct-ligated cirrhotic rats with portal hypertension. J Hepatol 2002; 36:600-6. [PMID: 11983442 DOI: 10.1016/s0168-8278(02)00037-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND/AIMS Nitric oxide and angiotensin play important roles in the pathogenesis of the hemodynamic derangement in cirrhosis and portal hypertension. The hemodynamic effects of losartan, an angiotensin II type 1 receptor antagonist, in cirrhotic patients with portal hypertension are conflicting. This study was undertaken to explore the possible mechanism of action of losartan on portal hypertension in cirrhotic rats produced by bile duct ligation (CBL). METHODS Three weeks after surgery, CBL and sham-operated rats randomly received vehicle or losartan (3 mg/kg per 12 h by gavage) for 1 week. Hemodynamic values, hormone levels, and aortic eNOS protein expression were measured after drug administration. RESULTS In CBL rats, 1-week losartan treatment decreased portal pressure and ameliorated hyperdynamic circulation associated with a blunted vascular response to N(omega)-nitro-L-arginine methyl ester infusion. The hematocrit increased and the plasma volume, aldosterone, plasma renin activity, norepinephrine, and nitrate and nitrite levels decreased. The eNOS protein expression was reduced in CBL rats receiving losartan compared with those receiving vehicle. CONCLUSIONS One-week losartan treatment in CBL rats decreased portal pressure and ameliorated hyperdynamic circulation. In addition to the suppression of renin-angiotensin axis, the reduced aortic eNOS protein expression may play a partial role for the mechanism of action of losartan in CBL rats.
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Affiliation(s)
- Ying-Ying Yang
- Division of Gastroenterology, Department of Medicine, National Yang-Ming University School of Medicine and Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 11217, Taiwan
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13
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Nadal FJA, Atucha NM, Iyu D, García-Estañ J. Interaction of nitric oxide with calcium in the mesenteric bed of bile duct-ligated rats. Br J Pharmacol 2002; 135:489-95. [PMID: 11815385 PMCID: PMC1573159 DOI: 10.1038/sj.bjp.0704504] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We have analysed the interaction of NO with calcium in order to study the molecular mechanisms responsible for the vascular hyporesponse of liver cirrhosis. The experiments have been performed in the isolated and perfused mesenteric arterial bed of rats with bile duct ligation (BDL) and their controls. While perfusing the vessels with normal Krebs, methoxamine (MTX) or KCl produced a lower pressor response in the BDL mesenteries. The NO synthesis inhibitor N(w)-nitro-L-arginine (NNA) potentiated those responses and abolished the differences between groups. The administration of MTX under perfusion with zero calcium-Krebs, to analyse the intracellular release of calcium, also induced a lower response in the BDL mesenteries and NNA potentiated and normalized the response. To investigate calcium entry, the vessels were perfused with zero-calcium Krebs containing high potassium to open voltage-dependent calcium channels. Then, the addition of calcium (10(-1) - 3 x 10(-3) M) produced a lower pressor response in the BDL vessels, that was corrected by NNA. To study calcium entry through receptor-operated channels, the vessels were perfused with zero-calcium Krebs containing MTX. The addition of calcium elevated the perfusion pressure less in the BDL mesenteries than in the control and NNA potentiated the responses and eliminated the between groups differences. When calcium entry through both voltage- and receptor-operated channels was simultaneously analysed, similar results were obtained. In the mesenteric bed of bile duct ligated rats, an excess of nitric oxide affects vascular calcium regulation through an interaction with both calcium entry and intracellular calcium release.
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Affiliation(s)
| | - Noemí M Atucha
- Departamento de Fisiología, Facultad de Medicina, Murcia, Spain
| | - David Iyu
- Departamento de Fisiología, Facultad de Medicina, Murcia, Spain
| | - Joaquín García-Estañ
- Departamento de Fisiología, Facultad de Medicina, Murcia, Spain
- Author for correspondence:
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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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Barriere E, Tazi KA, Rona JP, Pessione F, Heller J, Lebrec D, Moreau R. Evidence for an endothelium-derived hyperpolarizing factor in the superior mesenteric artery from rats with cirrhosis. Hepatology 2000; 32:935-41. [PMID: 11050042 DOI: 10.1053/jhep.2000.19290] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In cirrhosis, in splanchnic arteries, endothelium-dependent relaxation may persist even if overactive nitric oxide synthase (NOS) and cyclooxygenase (COX) are inhibited. In normal arteries, a significant endothelium-dependent relaxation to acetylcholine persists after NOS/COX inhibition. This relaxation is caused by smooth muscle cell (SMC) membrane hyperpolarization, which is sensitive to a combination of the potassium channel blockers apamin and charybdotoxin, and is mediated by an endothelium-derived hyperpolarizing factor (EDHF). The aim of this study was to detect EDHF and evaluate its pathophysiologic role in isolated superior mesenteric arteries from cirrhotic rats. Arterial rings were obtained and exposed to N(w)-nitro-L-arginine (L-NNA, a NOS inhibitor) and indomethacin (a COX inhibitor). Acetylcholine-induced membrane potential responses and concentration-response curves to the relaxant of acetylcholine were obtained with and without apamin plus charybdotoxin. Acetylcholine-induced responses were measured in certain rings from endothelium-denuded arteries. Contractions caused by the alpha(1)-adrenoceptor agonist phenylephrine were obtained in cirrhotic and normal rings with and without apamin and charybdotoxin. Significant acetylcholine-induced, endothelium-dependent, apamin- and charybdotoxin-sensitive, SMC membrane hyperpolarization and relaxation were found. An apamin- and charybdotoxin-sensitive hyporesponsiveness to the contractile action of phenylephrine was found in cirrhotic rings. In conclusion, in cirrhotic rats, in the superior mesenteric artery exposed to NOS/COX-inhibitors, an EDHF exists that may replace NOS/COX products to induce endothelium-dependent arterial relaxation.
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Affiliation(s)
- E Barriere
- Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM U-481, Hôpital Beaujon, Clichy, France
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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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Dabagh K, Said O, Lebrec D, Bomzon A. Down-regulation of vascular alpha1-adrenoceptors does not account for the loss of vascular responsiveness to catecholamines in experimental cholestasis. LIVER 1999; 19:193-8. [PMID: 10395038 DOI: 10.1111/j.1478-3231.1999.tb00035.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
AIMS/BACKGROUND Vascular hyporesponsiveness to sympathomimetic stimulation occurs in jaundice. Recently, we reported that this vascular adrenergic hyporesponsiveness was associated with the loss of reactivity of vascular alpha1-adrenoceptors. This study examines the possibility that the vascular adrenergic hyporesponsiveness is due to down-regulation of vascular alpha1-adrenoceptors. METHODS This question was addressed by measuring the changes in the plasma norepinephrine (NE) and epinephrine (E) concentrations, determined by high performance liquid chromatography, and the affinity and number of alpha1-adrenoceptors determined by a competitive antagonist radioligand binding assay in vascular smooth muscle membranes prepared from 3-day bile duct ligated (BDL) rats. The results were compared to data obtained from 3-day bile duct manipulated (sham-operated; SO) and control (C) rats. RESULTS Compared to C and SO rats, the plasma concentrations of NE and E in the BDL rats were significantly elevated reflecting increased sympathetic nervous system activity. BDL did not change either the affinity or the number of vascular alpha1-adrenoceptors. CONCLUSIONS Since the affinity and number of vascular alpha1-adrenoceptors were unchanged in the face of elevated plasma concentrations of catecholamines in the BDL rats, we have concluded that down-regulation of vascular alpha1-adrenoceptors does not account for the vascular adrenergic hyporesponsiveness in experimental cholestasis.
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Affiliation(s)
- K Dabagh
- Department of Pharmacology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa
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18
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Heller J, Schepke M, Gehnen N, Molderings GJ, Müller A, Erhard J, Spengler U, Sauerbruch T. Altered adrenergic responsiveness of endothelium-denuded hepatic arteries and portal veins in patients with cirrhosis. Gastroenterology 1999; 116:387-93. [PMID: 9922320 DOI: 10.1016/s0016-5085(99)70136-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS Patients with cirrhosis are characterized by a reduced splanchnic vascular resistance and a hyporeactivity to adrenergic vasoconstrictors. So far, their adrenergic splanchnic vascular responsiveness has not been evaluated in vitro. We compared responses to alpha1- and beta2-adrenoceptor stimulation of hepatic arteries and portal veins of patients with cirrhosis undergoing transplantation with those of organ donors. METHODS Isometric contractions of endothelium-denuded vessel rings were induced cumulatively by methoxamine and relaxations by isoproterenol. Results are expressed as percentage of the contraction obtained by 85 mmol/L KCl or of the relaxation obtained by 100 micromol/L papaverine, respectively. RESULTS Maximal methoxamine-induced contractions were reduced in cirrhotic hepatic arteries (cirrhosis, 51.8% +/- 6.8%; donor, 89.9% +/- 6.6%; P < 0.01) and portal veins (cirrhosis, 49.2% +/- 6.4%; donor, 94.0% +/- 5.3%; P < 0.01). In cirrhosis, isoproterenol induced a less marked relaxation of hepatic arteries (cirrhosis, 46.6% +/- 3.2%; donor, 100.3% +/- 4.4%; P < 0. 01) but an increased relaxation of portal veins (cirrhosis, 41.9% +/- 6.2%; donor, 26.2% +/- 2.8%; P < 0.01). CONCLUSIONS In cirrhosis, endothelium-free hepatic arteries are hyporeactive to alpha1- and beta2-adrenoceptor agonists, and portal veins are hyporeactive to alpha1- but hyperreactive to beta2-adrenoceptor agonists. These findings support the in vivo findings of a hyporesponsiveness to adrenergic vasoconstrictors in patients with cirrhosis.
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Affiliation(s)
- J Heller
- Department of General Internal Medicine, University of Bonn, Germany
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Huang YT, Lin HC, Tsai JF, Hou MC, Lee SD, Hong CY. Vascular hyporeactivity persists despite increased contractility after long-term administration of isosorbide dinitrate in portal hypertensive rats. J Hepatol 1998; 28:1037-44. [PMID: 9672181 DOI: 10.1016/s0168-8278(98)80354-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND/AIMS Portal hypertension is associated with decreased vascular responsiveness to vasoconstrictors, which may contribute to the hyperdynamics. Isosorbide dinitrate is an effective portal hypotensive drug. The present study aimed to investigate whether chronic administration of isosorbide dinitrate could affect vascular responsiveness in portal hypertensive rats. METHODS Portal hypertension was induced by partial portal vein ligation. Sham-operated (Sham) rats served as controls. There were four animal groups for this study: portal vein ligation-isosorbide dinitrate group, portal vein ligation-vehicle (Veh) group, Sham-isosorbide dinitrate group and Sham-Veh group. Isosorbide dinitrate (5 mg x kg(-1) x 12 h(-1) was given by gavage for 8 days starting 1 day before ligation and continuing thereafter. Mesenteric arteries were removed for contractile study after hemodynamic measurement. RESULTS Contractile responses to KCI (15-90 mM) and phenylephrine (10(-9)-10(-4) M) were recorded. Both vascular reactivity and sensitivity were significantly reduced in portal vein ligation rats as compared to Sham rats. Chronic isosorbide dinitrate treatment reduced portal venous pressure in portal vein ligation rats. Moreover, the maximal contractile responses to KCl and phenylephrine were significantly enhanced in both portal vein ligation and Sham rats after isosorbide dinitrate treatment, but relative hyporeactivity persisted in portal vein ligation rats. In contrast, a single dose of isosorbide dinitrate did not alter the contractile sensitivity or reactivity to KCl or phenylephrine in either portal vein ligation or Sham rats. CONCLUSION Our results show that long-term administration of isosorbide dinitrate enhanced vascular contractility in both portal vein ligation and Sham rats, but relative hyporeactivity persisted in portal vein ligation rats.
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Affiliation(s)
- Y T Huang
- Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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20
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Abstract
Portal hypertension is a common complication of chronic liver disease. Increased resistance to portal blood flow through a cirrhotic liver initiates the development of portal hypertension. In addition, alteration of neural and humoral regulations, endothelins, and stellate cells all contribute to the increased intrahepatic resistance. Moreover, the collateral circulation represents an additional site of increased resistance to portal blood flow. Increased splanchnic blood flow appears to play an important role in the maintenance of chronic portal hypertension. Several mechanisms have been proposed to explain this haemodynamic derangement including increased circulating vasodilators, endothelial-derived vasodilators, and decreased vascular reactivity to vasoconstrictors. Finally, the development of portal hypertension induces peripheral arterial vasodilation. The arterial vasodilatation may result in an increase in vascular underfilling which in turn leads to sodium retention and plasma volume expansion. The increased plasma volume is necessary for the development of increased cardiac output and the full expression of hyperdynamic circulation in portal hypertension.
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Affiliation(s)
- Y T Tsai
- Taichung Veterans General Hospital, Taiwan, ROC
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21
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Heinemann A, Wachter CH, Holzer P, Fickert P, Stauber RE. Nitric oxide-dependent and -independent vascular hyporeactivity in mesenteric arteries of portal hypertensive rats. Br J Pharmacol 1997; 121:1031-7. [PMID: 9222564 PMCID: PMC1564775 DOI: 10.1038/sj.bjp.0701220] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. Increased production of nitric oxide (NO) has been suggested to underlie both the vascular hyporeactivity to vasoconstrictors and the splanchnic vasodilatation seen in portal hypertension. This study assessed the role of NO in the vasoconstrictor hyporeactivity of portal vein-ligated (PVL) rats in isolated and in situ perfused mesenteric arterial beds. 2. Isolated perfused mesenteric arteries of PVL rats were significantly less reactive to noradrenaline (NA), methoxamine (METH), arginine vasopressin (AVP) and endothelin-1 (ET-1) than those from sham-operated (Sham) rats. 3. Blockade of NO synthesis with NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) in isolated perfused mesenteric arteries from PVL rats restored the reactivity to bolus injections of AVP and ET-1, but had little effect on the hyporeactivity to NA or METH. Cyclo-oxygenase inhibition with indomethacin (5 microM) likewise did not restore reactivity to METH of isolated perfused mesenteric arteries of PVL rats. 4. The hyporeactivity to METH seen in isolated perfused mesenteric arteries from PVL rats was reduced by low concentrations of AVP (20 nM) or ET-1 (1 nM) which per se caused only a slight increase in perfusion pressure. When L-NAME (100 microM) was combined with AVP (20 nM) or ET-1 (1 nM), respectively, reactivity to METH of isolated perfused mesenteric arteries of PVL rats was restored to the level seen in Sham rats. These effects of AVP and ET-1 were not mimicked by precontracting the vessels with 5-hydroxytryptamine (5 microM). 5. The differential effects of L-NAME and AVP on the hyporesponsiveness to methoxamine and AVP were corroborated by experiments performed with the in situ perfused mesenteric vascular bed preparation. 6. These data indicate that both NO-dependent and NO-dependent mechanisms are involved in the vasoconstrictor hyporesponsiveness of mesenteric arteries from portal hypertensive rats. The hyporeactivity to AVP and ET-1 is mediated by NO whereas the reduced responsiveness to adrenoceptor agonists appears to be predominantly NO-independent AVP and ET-1, in addition, seem to inhibit the NO-independent mechanism of vascular hyporeactivity, since the hyporesponsiveness to METH was reduced in the presence of AVP or ET-1 and abolished by the combination of these peptides with L-NAME.
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Affiliation(s)
- A Heinemann
- Department of Experimental and Clinical Pharmacology, Universitätsplatz 4, Graz, Austria
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22
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Huang YT, Chang SP, Lin HC, Yang MC, Hong CY. Inositol phosphate responses in portal veins from portal hypertensive rats: receptor- and nonreceptor-mediated responses. J Hepatol 1997; 26:376-81. [PMID: 9059960 DOI: 10.1016/s0168-8278(97)80055-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND/AIMS Venous hyporesponsiveness in portal hypertension has been reported previously by us. The present study was undertaken to investigate possible changes of phosphoinositide signal transduction pathway in the portal veins from portal hypertensive rats METHODS Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for measurement of [3H]inositol phosphate responses to both receptor- and nonreceptor-mediated stimuli. RESULTS Basal [3H]inositol phosphate formation was similar between the two groups. Both phenylephrine and angiotensin II stimulated [3H]inositol phosphate formation in portal veins, but the responses were attenuated in the portal hypertensive group. In contrast, the [3H]inositol phosphate formation by nonreceptor-mediated stimuli (GTP gamma S, NaF/AlCl3, and phospholipase C) was similar between the two groups. CONCLUSION Our results showed that the receptor-mediated [3H]inositol phosphate formation was attenuated, while the non-receptor-mediated formation was unaltered, in the portal vein from portal hypertensive rats.
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Affiliation(s)
- Y T Huang
- Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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23
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Moreno L, Martínez-Cuesta MA, Piqué JM, Bosch J, Esplugues JV. Anatomical differences in responsiveness to vasoconstrictors in the mesenteric veins from normal and portal hypertensive rats. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1996; 354:474-80. [PMID: 8897451 DOI: 10.1007/bf00168439] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The present study evaluates the effects of pre-hepatic portal hypertension, induced in rats by partial portal vein ligation, on the responsiveness of rostral (proximal) and caudal (distal) rings from the mesenteric vein. The anatomical origin of the sample influenced the response to vasoconstrictors in sham-operated animals, and this pattern of reactivity was specifically modified in portal-ligated rats. In veins from sham-operated rats, contraction induced by a submaximal concentration of KCl (60 mM) was greater in proximal than in distal rings. Vasopressin and 5-hydroxytryptamine contracted mainly distal rings, methoxamine showed a greater effect on proximal rings, and endothelin-1 and angiotensin-II contracted vein rings independently of their anatomical origin. In veins from portal hypertensive rats, response to KCl (60 mM) were increased in distal rings, and all rings exhibited enhanced reactivity to vasopressin and 5-hydroxyptyptamine as well as attenuation of the response to methoxamine. Responses to endothelin-1 were decreased in proximal vein rings from portal hypertensive rats whereas responses to angiotensin-II were not influenced by the anatomical origin. Incubation with atropine, propranolol or indomethacin, did not modify the responses to vasopressin and 5-hydroxytryptamine in tissues from either sham-operated or portal hypertensive animals. Likewise, the hyporeactivity to methoxamine and endothelin-1 in rings from portal hypertensive rats persisted in the presence of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester. These results suggest the physiological existence of anatomical differences in the responsiveness to vasoconstrictors throughout the mesenteric vein and that changes in the responsiveness of the mesenteric vein induced by portal hypertension are specific for each agonist and possibly result from individual variations at a receptor or post-receptor level.
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Affiliation(s)
- L Moreno
- Department of Pharmacology, Faculty of Medicine, University of Valencia, Spain
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Chiou WF, Liao JF, Shum AY, Chen CF. Mechanisms of vasorelaxant effect of dehydroevodiamine: a bioactive isoquinazolinocarboline alkaloid of plant origin. J Cardiovasc Pharmacol 1996; 27:845-53. [PMID: 8761852 DOI: 10.1097/00005344-199606000-00012] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We examined the mechanisms underlying the vasorelaxant effect of dehydroevodiamine (DeHE), one of the bioactive components of the Chinese herbal drug Evodia rutaecarpa that has been shown to produce vasorelaxant and hypotension. DeHE (10(-7)-10(-4) M) concentration-dependently relaxed isolated rat mesenteric arteries precontracted with phenylephrine (PE). This vasorelaxant potency was diminished by 15% by endothelial removal, L-NG-nitro arginine, or methylene blue (MB), but not indomethacin treatment, indicating that the vasorelaxant effect of DeHE was partially endothelium dependent and mediated by nitric oxide (NO) and the cyclic GMP pathway. In endothelium-denuded preparations, DeHE caused a rightward shift of the contractile concentration-response curve (CRC) to PE in a dose-dependent manner with a pA2 value of 6.15. Maximal response was unaffected. Receptor binding assay indicated that DeHE competed with alpha 1-adrenoceptor ligand prazosin with a Ki value of 3.57 microM. Potassium channel activity-attenuating conditions such as increased level of extracellular K+ (20 mM) and treatment with the antagonist tetraethylammonium (TEA) significantly inhibited DeHE's effect, suggesting a mode of action similar to that of a potassium channel activator. In addition, high concentrations of DeHE (3 x 10(-5) and 10(-4) M) relaxed high K+ (80 mM)-evoked contraction, indicating that DeHE might possess K+ channel blocking properties. Multiple-action mechanisms, including endothelium dependence, alpha 1-adrenoceptor blockade, K+ channel activation, and Ca2+ channel blockade were probably involved in the vasorelaxant effects of DeHE.
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Affiliation(s)
- W F Chiou
- National Research Institute of Chinese Medicine, Taipei Hsien, Taiwan. R.O.C
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25
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Atucha NM, Ortíz MC, Martínez C, Quesada T, García-Estañ J. Role of protein kinase C in mesenteric pressor responses of rats with portal hypertension. Br J Pharmacol 1996; 118:277-82. [PMID: 8735627 PMCID: PMC1909636 DOI: 10.1111/j.1476-5381.1996.tb15399.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. Hyporesponsiveness to vasoconstrictors is a characteristic abnormality of liver diseases of uncertain origin. In the present study, we have evaluated the involvement of protein kinase C (PKC) in the reduced pressor response to methoxamine (MTX) of a rat model of portal hypertension induced by partial portal vein ligation (PVL). Experiments were performed in the isolated and perfused mesentery. 2. The pressor response to MTX was reduced in PVL compared to that of control animals (Sham) and pretreatment with NG-nitro-L-arginine (L-NOARG, 10(-4) M) or removal of the endothelium potentiated the response of both groups. However, only removal of the endothelium completely eliminated the reduced pressor response to MTX of the PVL vessels. 3. Pretreatment of the mesentric vessels with calphostin C (10(-6) M), a PKC inhibitor, reduced the response to MTX of Sham to a level similar to that of untreated PVL vessels, but did not change that of PVL animals. 4. Mesenteric pressor responses to a PKC activator, phorbol 12,13-dibutyrate (PDBu), were similar in vessels from both PVL and Sham rats and pretreatment with L-NOARG or removal of the endothelium enhanced those responses while indomethacin (10(-5) M) decreased them. In all cases, the responses to PDBU were similar in PVL vessels compared to Sham. 5. These results indicate that the reduced pressor response to MTX of the mesenteric vascular bed of PVL rats is due to an endothelial alteration, compatible with an enhanced production of nitric oxide. The lack of response to calphostin C in PVL vessels suggests an impairment in agonist-induced PKC activation. Since direct activation of PKC induces a normal pressor response, it is concluded that the endothelial alteration interacts with the mechanism producing PKC activation, which results in a lower pressor response of the PVL mesenteric vaculature.
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Affiliation(s)
- N M Atucha
- Departamento de Fisiología, Facultad de Medicina, Murcia, Spain
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26
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Huang YT, Lin HC, Yu PC, Lee FY, Tsai YT, Lee SD, Yang MC. Decreased vascular reactivity of portal vein in rats with portal hypertension. J Hepatol 1996; 24:194-9. [PMID: 8907573 DOI: 10.1016/s0168-8278(96)80029-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND/AIMS Vascular hyporesponsiveness in portal hypertension is well documented in the arterial tissue. The present study aimed to investigate the possible changes in the portal vein from portal hypertensive rats. METHODS Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for contractile study and measurement of cAMP, cGMP and [Ca2+]i. RESULTS In vitro tension preparation showed a decreased maximum response to norepinephrine in portal vein of portal vein ligated rats (38.3 +/- 4.1 vs. 23.4 +/- 1.5 mN/mm2). The pA2 values of WB4101 and yohimbine (alpha1- and alpha2-adrenoceptor antagonist, respectively) were not different between the two groups. Tissue cAMP (14.4 +/- 0.9 vs. 12.2 +/- 0.7 pmol/mg protein), but not cGMP, content was increased and intracellular calcium [Ca2+]i levels (247 +/- 9 vs. 281 +/- 13 nM) were decreased in portal vein ligated rats. CONCLUSIONS These results showed that in portal vein from portal vein ligated rats, vascular hyporesponsiveness and an increase in basal cAMP content and a decrease in basal [Ca2+]i were observed.
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Affiliation(s)
- Y T Huang
- Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taiwan
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27
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Lin HC, Tsai YT, Yang MC, Lee FY, Hou MC, Chen LS, Lee SD. Effect of octreotide on total effective vascular compliance in patients with posthepatitic cirrhosis. J Hepatol 1996; 24:81-7. [PMID: 8834029 DOI: 10.1016/s0168-8278(96)80190-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND/AIMS This study aimed to evaluate the effect of octreotide on total effective vascular compliance, measured during rapid volume expansion, in patients with posthepatitic cirrhosis. METHODS Twenty-nine patients with posthepatitic cirrhosis were randomly assigned to receive a 100-micrograms/h infusion of octreotide after a 100-micrograms bolus (n = 15), or a placebo (n = 14). Hemodynamic measurements were recorded before and 30 min after drug administration. Thereafter, rapid volume expansion was performed in each patient and hemodynamic measurements were repeated immediately after volume expansion. RESULTS Before volume expansion, placebo administration did not affect any of the hemodynamic values, while the hepatic blood flow was significantly decreased following octreotide administration. After volume expansion, the hemodynamic changes were similar between patients receiving octreotide and the placebo. However, the increase in right atrial pressure from the beginning to the end of volume expansion was higher and the total effective vascular compliance was lower in patients receiving octreotide (+3.5 +/- 0.3 mmHg, p = 0.05 and 1.69 +/- 0.16 ml.mmHg-1.kg-1, p < 0.05) compared to patients receiving placebo (+2.5 +/- 0.3 mmHg, 2.60 +/- 0.34 ml.mmHg-1.kg-1). CONCLUSIONS The present study suggests that octreotide decreased total effective vascular compliance in patients with posthepatitic cirrhosis. It is possible that, in patients with posthepatitic cirrhosis, venoconstriction was induced following octreotide administration.
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Affiliation(s)
- H C Lin
- Department of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China
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Huang YT, Wang GF, Chen CF, Chen CC, Hong CY, Yang MC. Fructus aurantii reduced portal pressure in portal hypertensive rats. Life Sci 1995; 57:2011-20. [PMID: 7475952 DOI: 10.1016/0024-3205(95)02195-o] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The purpose of this study was to investigate the effects of Fructus Aurantii (the unripe fruits of Citrus aurantium L.) on portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated (Sham) rats served as controls. Hemodynamic and in vitro contractile studies were performed at 14 days after surgery. Both the aqueous extract of Fructus Aurantii and synephrine, one of its purified principles with pressor activity, were infused into the conscious PVL and Sham rats via a syringe pump. Fructus Aurantii (1.25, 2.5, & 5.0 mg/kg/min) dose-dependently reduced portal pressure in PVL and Sham rats, with the percentage change in portal pressure more pronounced in PVL rats. Mean arterial pressure was dose-dependently elevated by Fructus Aurantii. Synephrine (0.095, 0.19, & 0.38 mg/kg/min) also dose-dependently reduced portal pressure and elevated mean arterial pressure in PVL and Sham rats. Fructus Aurantii (2.8-280 micrograms/ml) induced dose-dependent contractile responses mainly in aorta and mesenteric artery, but little response in portal vein. The results showed that Fructus Aurantii infusion reduced portal pressure, possibly by way of arterial vasoconstriction.
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Affiliation(s)
- Y T Huang
- Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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Affiliation(s)
- R Moreau
- Laboratoire d'Hémodynamique Splanchnique, INSERM U-24, Hôpital Beaujon, Clichy, France
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30
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Huang YT, Yu PC, Lee MF, Lin HC, Hong CY, Yang MC. Decreased vascular contractile and inositol phosphate responses in portal hypertensive rats. Can J Physiol Pharmacol 1995; 73:378-82. [PMID: 7648517 DOI: 10.1139/y95-048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The purpose of this study was to investigate the vascular contractile and inositol phosphate responses in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated rats served as controls. Pressures, vasoconstrictor responses, and inositol phosphate responses were determined at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower, in PVL rats. Dose-dependent contractile responses were observed for both norepinephrine (1 x 10(-8) - 3 x 10(-6) M) and vasopressin (3 x 10(-10) - 3 x 10(-8) M) in the tail artery of both groups. The contractile response to norepinephrine was significantly decreased in PVL rats compared with controls at all doses. The contractile response to vasopressin was significantly decreased in PVL rats at higher doses. After myo-[3H]inositol incorporation in tail artery, the levels of 3H-labelled phosphatidylinositols (cpm/mg) were similar between the two groups. Norepinephrine (10(-7) - 10(-5) M) and vasopressin (10(-10) - 10(-8) M) dose dependently stimulated the 3H-labelled inositol phosphate production in the tail artery of both PVL and sham-operated rats. However, the response was significantly lower in PVL rats. The results suggested that the attenuation of vascular contractile responses in portal hypertension was reflected in the phosphoinositide messenger system.
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Affiliation(s)
- Y T Huang
- Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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Hartleb M, Moreau R, Gaudin C, Lebrec D. Lack of vascular hyporesponsiveness to the L-type calcium channel activator, Bay K 8644, in rats with cirrhosis. J Hepatol 1995; 22:202-7. [PMID: 7540637 DOI: 10.1016/0168-8278(95)80430-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND/AIMS In cirrhosis, the mechanism(s) for vascular hyporesponsiveness to vasoconstrictors such as, alpha 1-adrenoceptor agonists, vasopressin and angiotensin II, are unclear. Moreover, vascular reactivity to substances such as L-type calcium channel activators is unknown. METHODS Thus, pressor dose-response curves to vasoconstrictors [phenylephrine (an alpha 1-agonist, 0.1-500 micrograms/kg) angiotensin II (10-500 ng/kg), vasopressin (0.01-5 IU/kg), and Bay K 8644 (an L-type calcium channel activator, 0.5-50 micrograms/kg)] were obtained in normal rats and in rats with secondary biliary cirrhosis. All experiments were performed in ganglionic-blocked animals to limit the influence of cardiovascular reflexes. Doses of vasoconstrictor necessary to obtain a 40 mmHg increase in arterial pressure (D40) were calculated. RESULTS Compared to normal animals, rats with cirrhosis had significantly higher D40 values for angiotensin II (171 +/- 57 vs. 344 +/- 41 ng/kg), phenylephrine (2.6 +/- 0.2 vs. 26.4 +/- 10.7 micrograms/kg) and vasopressin (73 +/- 19 vs. 401 +/- 150 mU/kg). Pressor responses to Bay K 8644 did not differ between normal rats and rats with cirrhosis (8.8 +/- 0.9 vs. 10.5 +/- 2.1 micrograms/kg). CONCLUSIONS In conclusion, this study shows that cirrhosis produces vascular hyporeactivity to phenylephrine, vasopressin and angiotensin II but not to Bay K 8644. Therefore, cirrhosis impairs certain constrictor mechanisms which are shared by phenylephrine, angiotensin II and vasopressin but which do not contribute to the vascular response to Bay K 8644.
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Affiliation(s)
- M Hartleb
- Laboratoire d'Hémodynamique Splanchnique, INSERUM U-24, Hôpital Beaujon, Clichy, France
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