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Garcia SM, Matheson B, Morales-Loredo JH, Jernigan NL, Kanagy NL, Resta TC, Clark RM, Shekarriz R, Gonzalez Bosc LV. Hydrogen sulfide and miR21 are suitable biomarkers of hypoxic exposure. Am J Physiol Regul Integr Comp Physiol 2022; 323:R900-R909. [PMID: 36250874 PMCID: PMC9678419 DOI: 10.1152/ajpregu.00199.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/12/2022] [Accepted: 10/13/2022] [Indexed: 11/22/2022]
Abstract
Hypoxia is the reduction of alveolar partial pressure of oxygen ([Formula: see text]). Military members and people who practice recreational activities from moderate to high altitudes are at risk for hypoxic exposure. Hypoxemia's signs and symptoms vary from asymptomatic to severe responses, such as excessive hypoxic ventilatory responses and residual neurobehavioral impairment. Therefore, it is essential to identify hypoxia-induced biomarkers to indicate people with exposure to hypoxia. Advances have been made in understanding physiological responses to hypoxia, including elevations in circulating levels of endothelin 1 (ET-1) and microRNA 21 (miR-21) and reduction in circulating levels of hydrogen sulfide (H2S). Although the levels of these factors change upon exposure to hypoxia, it is unclear if these changes are sustained on return to normoxia. We hypothesize that hypoxia-induced ET-1 and miR-21 remain elevated, whereas hypoxia-reduction in H2S sustains after returning to normoxic conditions. To test this hypothesis, we exposed male rats to 6 h of 12% O2 and measured circulating levels of ET-1 and miR-21, pre, during, and posthypoxia. We found that ET-1 plasma levels increased in response to hypoxia but returned to normal levels within 30 min after the restoration of normoxia. miR-21 plasma levels and transdermal H2S emissions decreased in response to hypoxia, remaining decreased on return to normoxia, thus following the biomarker criteria. Therefore, this study supports a unique role for plasma miR21 and transdermal H2S as hypoxia biomarkers that could be used to identify individuals after exposure to hypoxia.
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Affiliation(s)
- Selina M Garcia
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Benjamin Matheson
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Juan H Morales-Loredo
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Nikki L Jernigan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Nancy L Kanagy
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Thomas C Resta
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Ross M Clark
- Department of Surgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | | | - Laura V Gonzalez Bosc
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
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2
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Ider M, Naseri A, Ok M, Uney K, Erturk A, Durgut MK, Parlak TM, Ismailoglu N, Kapar MM. Biomarkers in premature calves with and without respiratory distress syndrome. J Vet Intern Med 2021; 35:2524-2533. [PMID: 34227155 PMCID: PMC8478053 DOI: 10.1111/jvim.16217] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/22/2021] [Accepted: 06/22/2021] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Approaches to the evaluation of pulmonary arterial hypertension (PAH) in premature calves by using lung-specific epithelial and endothelial biomarkers are needed. OBJECTIVE To investigate the evaluation of PAH in premature calves with and without respiratory distress syndrome (RDS) by using lung-specific epithelial and endothelial biomarkers and determine the prognostic value of these markers in premature calves. ANIMALS Fifty premature calves with RDS, 20 non-RDS premature calves, and 10 healthy term calves. METHODS Hypoxia, hypercapnia, and tachypnea were considered criteria for RDS. Arterial blood gases (PaO2 , PaCO2 , oxygen saturation [SO2 ], base excess [BE], and serum lactate concentration) were measured to assess hypoxia. Serum concentrations of lung-specific growth differentiation factor-15 (GDF-15), asymmetric dimethylarginine (ADMA), endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and surfactant protein D (SP-D) were measured to assess PAH. RESULTS Arterial blood pH, PaO2 , SO2 , and BE of premature calves with RDS were significantly lower and PaCO2 and lactate concentrations higher compared to non-RDS premature and healthy calves. The ADMA and SP-D concentrations of premature calves with RDS were lower and serum ET-1 concentrations higher than those of non-RDS premature and healthy calves. No statistical differences for GDF-15 and VEGF were found among groups. CONCLUSIONS AND CLINICAL IMPORTANCE Significant increases in serum ET-1 concentrations and decreases in ADMA and SP-D concentrations highlight the utility of these markers in the diagnosis of PAH in premature calves with RDS. Also, we found that ET-1 was a reliable diagnostic and prognostic biomarker for PAH and predicting mortality in premature calves.
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Affiliation(s)
- Merve Ider
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
| | - Amir Naseri
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
| | - Mahmut Ok
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
| | - Kamil Uney
- Faculty of Veterinary Medicine, Department of Pharmacology and ToxicologySelcuk UniversityKonyaTurkey
| | - Alper Erturk
- Faculty of Veterinary Medicine, Department of Internal MedicineMustafa Kemal UniversityHatayTurkey
| | - Murat K. Durgut
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
| | - Tugba M. Parlak
- Faculty of Veterinary Medicine, Department of Pharmacology and ToxicologySelcuk UniversityKonyaTurkey
| | - Nimet Ismailoglu
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
| | - Muhammed M. Kapar
- Faculty of Veterinary Medicine, Department of Internal MedicineSelcuk UniversityKonyaTurkey
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3
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The newborn sheep translational model for pulmonary arterial hypertension of the neonate at high altitude. J Dev Orig Health Dis 2021; 11:452-463. [PMID: 32705972 DOI: 10.1017/s2040174420000616] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Chronic hypoxia during gestation induces greater occurrence of perinatal complications such as intrauterine growth restriction, fetal hypoxia, newborn asphyxia, and respiratory distress, among others. This condition may also cause a failure in the transition of the fetal to neonatal circulation, inducing pulmonary arterial hypertension of the neonate (PAHN), a syndrome that involves pulmonary vascular dysfunction, increased vasoconstrictor tone and pathological remodeling. As this syndrome has a relatively low prevalence in lowlands (~7 per 1000 live births) and very little is known about its prevalence and clinical evolution in highlands (above 2500 meters), our understanding is very limited. Therefore, studies on appropriate animal models have been crucial to comprehend the mechanisms underlying this pathology. Considering the strengths and weaknesses of any animal model of human disease is fundamental to achieve an effective and meaningful translation to clinical practice. The sheep model has been used to study the normal and abnormal cardiovascular development of the fetus and the neonate for almost a century. The aim of this review is to highlight the advances in our knowledge on the programming of cardiopulmonary function with the use of high-altitude newborn sheep as a translational model of PAHN.
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4
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Baumann P, Wiegert S, Greco F, Wellmann S, L'Abate P, Cannizzaro V. Mechanical ventilation strategies alter cardiovascular biomarkers in an infant rat model. Physiol Rep 2019; 6. [PMID: 29380954 PMCID: PMC5789718 DOI: 10.14814/phy2.13553] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/23/2017] [Accepted: 11/29/2017] [Indexed: 11/24/2022] Open
Abstract
Mechanical ventilation (MV) is routinely used in pediatric general anesthesia and critical care, but may adversely affect the cardiocirculatory system. Biomarkers are increasingly measured to assess cardiovascular status and improve clinical treatment decision-making. As the impact of mechanical ventilation strategies on cardiovascular biomarkers in ventilated infants is largely unknown, we conducted this retrospective study in a healthy in vivo infant rat ventilation model using 14-days old Wistar rats. We hypothesized that 2 h of mechanical ventilation with high and low positive end-expiratory pressure (PEEP), hyperoxemia, hypoxemia, hypercapnia, and hypocapnia would significantly impact B-type natriuretic peptide (BNP), vascular endothelial growth factor (VEGF), and endothelin-1 (ET-1). We found BNP to be driven by both high (9 cmH2 O) and low (1 cmH2 O) PEEP compared to ventilated control animals (P < 0.05). VEGF concentrations were associated with high PEEP, hyperoxemia, hypoxemia, and hypocapnia (P < 0.05), whereas ET-1 levels were changed only in response to hypoxemia (P < 0.05). In conclusion, the mode of mechanical ventilation alters plasma biomarker concentrations. Moreover, BNP and VEGF might serve as surrogate parameters for ventilation induced cardiovascular compromise and lung tissue damage. Furthermore, our data support the hypothesis, that sudden onset of hyperoxemia may trigger a quick VEGF release as a possible cellular survival reflex.
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Affiliation(s)
- Philipp Baumann
- Department of Intensive Care Medicine and Neonatology, University Children's Hospital of Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital of Zurich, Zurich, Switzerland
| | - Susanne Wiegert
- Department of Intensive Care Medicine and Neonatology, University Children's Hospital of Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital of Zurich, Zurich, Switzerland.,Zurich Centre for Integrative Human Physiology, Zurich, Switzerland
| | - Francesco Greco
- Department of Intensive Care Medicine and Neonatology, University Children's Hospital of Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital of Zurich, Zurich, Switzerland.,Zurich Centre for Integrative Human Physiology, Zurich, Switzerland
| | - Sven Wellmann
- Department of Neonatology, University Children's Hospital of Basel, Basel, Switzerland
| | - Pietro L'Abate
- Department of Intensive Care Medicine and Neonatology, University Children's Hospital of Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital of Zurich, Zurich, Switzerland
| | - Vincenzo Cannizzaro
- Department of Intensive Care Medicine and Neonatology, University Children's Hospital of Zurich, Zurich, Switzerland.,Children's Research Centre, University Children's Hospital of Zurich, Zurich, Switzerland.,Zurich Centre for Integrative Human Physiology, Zurich, Switzerland
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5
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Kylhammar D, Rådegran G. The principal pathways involved in the in vivo modulation of hypoxic pulmonary vasoconstriction, pulmonary arterial remodelling and pulmonary hypertension. Acta Physiol (Oxf) 2017; 219:728-756. [PMID: 27381367 DOI: 10.1111/apha.12749] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 06/10/2016] [Accepted: 07/04/2016] [Indexed: 12/13/2022]
Abstract
Hypoxic pulmonary vasoconstriction (HPV) serves to optimize ventilation-perfusion matching in focal hypoxia and thereby enhances pulmonary gas exchange. During global hypoxia, however, HPV induces general pulmonary vasoconstriction, which may lead to pulmonary hypertension (PH), impaired exercise capacity, right-heart failure and pulmonary oedema at high altitude. In chronic hypoxia, generalized HPV together with hypoxic pulmonary arterial remodelling, contribute to the development of PH. The present article reviews the principal pathways in the in vivo modulation of HPV, hypoxic pulmonary arterial remodelling and PH with primary focus on the endothelin-1, nitric oxide, cyclooxygenase and adenine nucleotide pathways. In summary, endothelin-1 and thromboxane A2 may enhance, whereas nitric oxide and prostacyclin may moderate, HPV as well as hypoxic pulmonary arterial remodelling and PH. The production of prostacyclin seems to be coupled primarily to cyclooxygenase-1 in acute hypoxia, but to cyclooxygenase-2 in chronic hypoxia. The potential role of adenine nucleotides in modulating HPV is unclear, but warrants further study. Additional modulators of the pulmonary vascular responses to hypoxia may include angiotensin II, histamine, serotonin/5-hydroxytryptamine, leukotrienes and epoxyeicosatrienoic acids. Drugs targeting these pathways may reduce acute and/or chronic hypoxic PH. Endothelin receptor antagonists and phosphodiesterase-5 inhibitors may additionally improve exercise capacity in hypoxia. Importantly, the modulation of the pulmonary vascular responses to hypoxia varies between species and individuals, with hypoxic duration and age. The review also define how drugs targeting the endothelin-1, nitric oxide, cyclooxygenase and adenine nucleotide pathways may improve pulmonary haemodynamics, but also impair pulmonary gas exchange by interference with HPV in chronic lung diseases.
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Affiliation(s)
- D. Kylhammar
- Department of Clinical Sciences Lund, Cardiology; Faculty of Medicine; Lund University; Lund Sweden
- The Section for Heart Failure and Valvular Disease; VO Heart and Lung Medicine; Skåne University Hospital; Lund Sweden
| | - G. Rådegran
- Department of Clinical Sciences Lund, Cardiology; Faculty of Medicine; Lund University; Lund Sweden
- The Section for Heart Failure and Valvular Disease; VO Heart and Lung Medicine; Skåne University Hospital; Lund Sweden
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6
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Kojonazarov B, Isakova J, Imanov B, Sovkhozova N, Sooronbaev T, Ishizaki T, Aldashev AA. Bosentan Reduces Pulmonary Artery Pressure in High Altitude Residents. High Alt Med Biol 2012; 13:217-23. [DOI: 10.1089/ham.2011.1107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Baktybek Kojonazarov
- Institute of Molecular Biology and Medicine, Bishkek, Kyrgyzstan
- University of Giessen Lung Center, Giessen, Germany
| | - Jainagul Isakova
- Institute of Molecular Biology and Medicine, Bishkek, Kyrgyzstan
| | - Bakytbek Imanov
- National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
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Abstract
It has been known for more than 60 years, and suspected for over 100, that alveolar hypoxia causes pulmonary vasoconstriction by means of mechanisms local to the lung. For the last 20 years, it has been clear that the essential sensor, transduction, and effector mechanisms responsible for hypoxic pulmonary vasoconstriction (HPV) reside in the pulmonary arterial smooth muscle cell. The main focus of this review is the cellular and molecular work performed to clarify these intrinsic mechanisms and to determine how they are facilitated and inhibited by the extrinsic influences of other cells. Because the interaction of intrinsic and extrinsic mechanisms is likely to shape expression of HPV in vivo, we relate results obtained in cells to HPV in more intact preparations, such as intact and isolated lungs and isolated pulmonary vessels. Finally, we evaluate evidence regarding the contribution of HPV to the physiological and pathophysiological processes involved in the transition from fetal to neonatal life, pulmonary gas exchange, high-altitude pulmonary edema, and pulmonary hypertension. Although understanding of HPV has advanced significantly, major areas of ignorance and uncertainty await resolution.
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Affiliation(s)
- J T Sylvester
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School ofMedicine, Baltimore, Maryland, USA.
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8
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Lalande S, Anderson PJ, Miller AD, Ceridon ML, Beck KC, O’Malley KA, Johnson JB, Johnson BD. Variability in pulmonary function following rapid altitude ascent to the Amundsen–Scott South Pole station. Eur J Appl Physiol 2011; 111:2221-8. [DOI: 10.1007/s00421-011-1864-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/01/2011] [Indexed: 11/29/2022]
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9
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Demiryurek AT, Maclean MR, Wadsworth RM, Kane KA. Effects of Hypoxia on Endothelin-1 Release from Human, Sheep and Rabbit Pulmonary Artery Rings. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/10623329409100963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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10
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Price LC, Howard LSGE. Endothelin receptor antagonists for pulmonary arterial hypertension: rationale and place in therapy. Am J Cardiovasc Drugs 2008; 8:171-85. [PMID: 18533738 DOI: 10.2165/00129784-200808030-00004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The last decade has seen significant advances in the understanding and treatment of pulmonary arterial hypertension (PAH). Three main pathways, involving endothelin, nitric oxide, and prostacyclin, have been identified in its pathogenesis and these have all led to the development of therapies in current use. While the nitric oxide and prostacyclin pathways require augmentation, the endothelin system is overactive in PAH, with increased endothelin synthesis and receptor expression and, therefore, requires blockade. There are two known endothelin receptors. The type A receptor, expressed in pulmonary artery media, mediates vasoconstriction and remodeling, whereas the function of the type B receptor is more complex. Like the type A receptor, the type B receptor mediates vasoconstriction and remodeling effects when expressed on smooth muscle cells and (myo)fibroblasts, yet functions to clear endothelin from the circulation and induce release of endogenous nitric oxide and prostacyclin, when activated in the pulmonary artery endothelium. Consequently, it is not clear from in vitro data whether the optimal strategy is to block only the type A receptor or both receptors. Phase III clinical studies show clear short-term physiologic benefit with both dual and selective endothelin blockade in PAH. Longer-term experience with bosentan, a dual receptor antagonist, has shown improved outcomes compared with historic control data and comparable survival to intravenous prostacyclin therapy. The newer selective blockers, sitaxsentan and ambrisentan, appear to have similar short-term efficacy, but long-term data are as yet either lacking or unpublished. They may be less hepatotoxic than bosentan, although long-term follow-up of patients receiving bosentan has shown this is not a significant problem. On the basis of available evidence, the endothelin receptor antagonists have become first-line therapy for patients with PAH, except in the most severely affected who still require treatment with intravenous prostacyclin. Although their use as part of combination therapy with other agents is widespread, the evidence for this is not as robust, but appropriate investigation is underway.
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Affiliation(s)
- Laura C Price
- Department of Cardiac Sciences, National Pulmonary Hypertension Service, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK
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11
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Abstract
The vascular endothelium plays a fundamental role in the basal and dynamic regulation of the circulation. Thus, it has a crucial role in the pathogenesis of hypertension. A spectrum of vasoactive substances is synthesised in the endothelium; of these, nitric oxide (NO), prostacyclin (PGI2) and endothelin (ET)-1 are the most important. There is a continuous basal release of NO determining the tone of peripheral blood vessels. Systemic inhibition of NO synthesis or scavenging of NO through oxidative stress causes an increase in arterial blood pressure. Also, the renin-angiotensin-aldosterone system has a major role in hypertension as it has a direct vasoconstrictor effect and important interactions with oxygen free radicals and NO. Prostacyclin, in contrast to NO, does not contribute to the maintenance of basal vascular tone of conduit arteries, but its effect on platelets is most important. ET acts as the natural counterpart to endothelium-derived NO and has an arterial blood pressure-raising effect in man. Anti-hypertensive therapy lowers blood pressure and may influence these different mediators, thus influencing endothelial function. In summary, due to its position between the blood pressure and smooth muscle cells responsible for peripheral resistance, the endothelium is thought to be both victim and offender in arterial hypertension. The delicate balance of endothelium-derived factors is disturbed in hypertension. Specific anti-hypertensive and anti-oxidant treatment is able to restore this balance.
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Affiliation(s)
- L E Spieker
- Cardiovascular Centre, Cardiology, Dep. of Internal Medicine, University Hospital, 8091 Zürich, Switzerland
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12
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Wang J, Oldner A, Winskog C, Edston E, Walther SM. Effects of endothelin receptor antagonism on acute lung injury induced by chlorine gas. Crit Care Med 2006; 34:1731-7. [PMID: 16625121 DOI: 10.1097/01.ccm.0000218815.46611.63] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To test the hypothesis that the endothelin system is involved in chlorine gas-induced lung injury. DESIGN Experimental study. SETTING Academic research laboratory. SUBJECTS Twenty-four domestic juvenile pigs. INTERVENTIONS Anesthetized, ventilated pigs were exposed to chlorine gas (400 parts per million in air) for 20 mins and then randomly allocated to four groups (n=6 in each group). The tezosentan pretreatment group received the dual endothelin receptor antagonist tezosentan 20 mins before and hyperoxic gas (Fio2 0.6) after chlorine gas exposure. The tezosentan postinjury treatment group received hyperoxic gas after chlorine gas exposure and tezosentan 60 mins later. Animals in the oxygen group received hyperoxic gas after chlorine gas exposure. Pigs in the fourth group (air) were ventilated with room air (Fio2 0.21) throughout the experiment. MEASUREMENTS AND MAIN RESULTS Hemodynamics, gas exchange, lung mechanics, and plasma endothelin-1 were evaluated for 6 hrs. Chlorine gas exposure induced an increase in circulating endothelin-1 by 90% (p<.05). The acute chlorine gas-induced rise in pulmonary vascular resistance was partly blocked by tezosentan pretreatment (p<.001). Tezosentan postinjury treatment also decreased pulmonary vascular resistance to levels significantly lower than in the air and oxygen groups (p<.001). Recovery of peak airway pressure was better in the tezosentan-treated groups than in the air group. There were significant linear relationships between circulating endothelin-1 and pulmonary vascular resistance (r=.47, p<.001) and endothelin-1 and peak airway pressure (r=.41, p<.001). These relationships were modified by tezosentan. CONCLUSIONS Tezosentan modified chlorine gas-induced pulmonary dysfunction, indicating that the endothelin system is involved in this mode of acute lung injury.
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Affiliation(s)
- Jianpu Wang
- Centre for Teaching and Research in Disaster Medicine and Traumatology, University of Linköping, Linköping, Sweden.
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13
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Biarent D, Hubloue I, Bejjani G, Mélot C, Jespers P, Naeije R, Leeman M. Role of endothelins and nitric oxide in the pulmonary circulation of perinatal lambs during hyperoxia and hypoxia. Pediatr Res 2006; 59:131-6. [PMID: 16327012 DOI: 10.1203/01.pdr.0000191138.34387.e2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Endothelins (ET) have opposite vascular effects mediated through different receptors: ET(A) receptors mediating vasoconstriction and ET(B) receptors mediating vasoconstriction as well as vasodilation. The role of ET in acute hypoxic pulmonary vasoconstriction (HPV) was studied after dual ET receptor blockade with bosentan and nitric oxide (NO) synthase inhibition with nitro-L-arginine (L-NA). We started from the hypothesis that ET antagonism may inhibit HPV but, if not, would do so after NO synthase inhibition. HPV was evaluated in anesthetized lambs, with an intact pulmonary circulation, by the increase in the mean pulmonary artery pressure (Ppa) minus occluded Ppa (Ppao) gradient in response to hypoxia (inspiratory oxygen fraction of 0.1) at different levels of pulmonary flow (multipoint pressure/flow relationships). ET receptor antagonism decreased pulmonary and systemic vascular tone both in hyperoxia and hypoxia. ET antagonism had no effect on HPV. NO synthase inhibition increased pulmonary vascular tone more in hypoxia than in hyperoxia so that HPV was enhanced. After L-NA, bosentan still decreased pulmonary vascular tone in hypoxia but did not affect the magnitude of HPV. The present results suggest that ET and NO are involved in the regulation of basal pulmonary vascular tone. Furthermore, the vasodilator effect of bosentan persisted in the presence of NO synthase inhibition, suggesting a non NO-dependent vasodilator mechanism. The results from these experiments are in agreement with the idea that ET do not play a major role in HPV in the perinatal lamb, even when it is enhanced by NO synthase inhibition.
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Affiliation(s)
- Dominique Biarent
- Laboratory of Physiology, Faculty of Medicine, Erasme Campus of the Free University of Brussels, Belgium.
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14
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Kanazawa F, Nakanishi K, Osada H, Kanamaru Y, Ohrui N, Uenoyama M, Masaki Y, Kanatani Y, Hiroi S, Tominaga S, Yakata-Suzuki A, Matsuyama S, Kawai T. Expression of endothelin-1 in the brain and lung of rats exposed to permanent hypobaric hypoxia. Brain Res 2005; 1036:145-54. [PMID: 15725412 DOI: 10.1016/j.brainres.2004.12.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Revised: 10/21/2004] [Accepted: 12/15/2004] [Indexed: 12/21/2022]
Abstract
High-altitude hypoxia causes pulmonary hypertension in humans and animals. Endothelin-1 (ET-1) is a novel and long-lasting vasoconstrictor. However, no study has dealt with the effects of a hypobaric hypoxic environment (HHE) on ET-1 activity in the brain. We examined 134 male rats permanently exposed to the equivalent of 5500 m altitude for 1 to 8 weeks. In these HHE rats, the mean pulmonary arterial pressure was significantly raised. The level of ET-1 protein, measured by enzyme immunoassay, increased rapidly in the lungs on exposure to HHE, but decreased in the brain. The level of ET-1 mRNA, measured by semiquantitative RT-PCR, was raised at 1, 4, and 6 weeks' exposure in the lungs and at 4 or more weeks' exposure in 3 of 8 brain regions. By in situ hybridization and immunohistochemistry of brain sections, ET-1 mRNA and protein were detected in the endothelial cells, neurons, and astrocyte-like cells in control rats. In HHE rats, the immunoreactive intensity for ET-1 protein decreased rapidly with time in these cells within the brain, although a few weakly ET-1 protein-positive cells were detected until 8 weeks' exposure to HHE. Only a few weakly ET-1 mRNA-positive endothelial cells were detected in any HHE rats. Although the reactivity for ET-1 mRNA had decreased significantly in neurons and astrocyte-like cells at 1 and 2 weeks' exposure to HHE, it was again strong in both types of cells at 4 weeks' exposure to HHE. These results raise the possibility that during exposure to HHE, ET-1 production in the lung may play a role in the development of pulmonary hypertension, while a decrease in ET-1 production within the brain may help to protect neurons by preventing or limiting the constriction of cerebral microvessels during the hypoxia induced by HHE.
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Affiliation(s)
- Fumiko Kanazawa
- Biochemical Section, 2nd Division, Aeromedical Laboratory, Japan Air Self-Defense Force, Tachikawa 190-0003, Japan
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15
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Zhang HY, Han DW, Wang XG, Zhao YC, Zhou X, Zhao HZ. Experimental study on the role of endotoxin in the development of hepatopulmonary syndrome. World J Gastroenterol 2005; 11:567-72. [PMID: 15641147 PMCID: PMC4250812 DOI: 10.3748/wjg.v11.i4.567] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [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 evaluate the role of intestinal endotoxemia in the genesis of hepatopulmonary syndrome.
METHODS: A rat model of cirrhosis was prepared with the method of compound factors. At the end of the eighth week, rats with cirrhosis were treated with 300 μg LPS/100 g body weight, and 1 g/rat of glycine about four h prior to LPS. After three h of LPS treatment, blood and tissues were collected for various measurements. Kupffer cells were isolated from male Wistar rats and cultured, and divided into five groups. Supernatant was harvested at 3 h after treatment with LPS for measurement of tumor necrosis factor-alpha (TNF-α).
RESULTS: Our results showed that in rats with cirrhosis, slowed and deepened breath with occasional pause was. PaO2, PaCO2 and standard bicarbonate (SB) in arterial blood were decreased. Arterial O2 and actual bicarbonate (AB) were markedly decreased. There was a close correlation between decreased O2 and endotoxin. Metabolic acidosis accompanying respiratory alkalosis was the primary type of acid-base imbalance. The alveolar-arterial oxygen gradient was sharply widened. Massive accumulation of giant macrophages in the alveolar spaces and its wall and widened alveolar wall architecture were observed. The number of bacterial translocations in mesenteric lymph nodes increased. The ratio of TC99M-MAA brain-over-lung radioactivity rose. Endotoxin, and TNF-α, endothelin-1 (ET-1), nitric oxide (NO) in plasma and ET-1, carbon monoxide (CO) in lung homogenates increased. After administration of a given dosage of LPS in rats with cirrhosis, various pathological parameters worsened. Plasma level of endotoxin was related to TNF-α, ET-1, NO in plasma and ET-1, NO, CO in lung homogenates. TNF-α level was related to ET-1 and NO in plasma and lung homogenates and CO in lung homogenate as well. The level of TNF-α increased after infusion of LPS into culture supernatant of Kupffer cells in vitro. However, TNF-α significantly decreased after pretreatment with glycine, PD98059 and SB212850. Glycine could antagonize the effect of LPS in vivo and in vitro.
CONCLUSION: Intestinal endotoxemia accompanying by cirrhosis may be an important mechanism in the development of hepatopulmonary syndrome in rats. Overproduction of TNF-α due to endotoxin stimulation of Kupffer cells via mitogen-activated protein kinase (MAPK) signal transduction pathway may be a major mechanism mediating the pathologic alterations of hepatopulmonary syndrome.
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Affiliation(s)
- Hui-Ying Zhang
- Institute of Hepatology, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
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16
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17
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Trakada G, Nikolaou E, Pouli A, Tsiamita M, Spiropoulos K. Endothelin-1 levels in interstitial lung disease patients during sleep. Sleep Breath 2004; 7:111-8. [PMID: 14569522 DOI: 10.1007/s11325-003-0111-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Hypoxemia stimulates endothelin-1 (ET-1) secretion. The reduction in alveolar ventilation during sleep is considered sufficient to account for the hypoxemia observed in patients with respiratory diseases. OBJECTIVE The aim of this study was to evaluate the arterial ET-1 levels and their relationship with pulmonary hypertension in patients with interstitial lung disease (ILD) during sleep. METHODS We examined 38 patients with ILD using formal polysomnography (electroencephalogram, electrocardiogram, airflow, respiratory muscle movement, oximeter) to detect the presence of nocturnal, nonapneic, oxyhemoglobin desaturation. All patients desaturated below a baseline sleep saturation of 90% for 5 minutes or more, reaching a nadir saturation of at least 85%. Each patient had already undergone right heart catheterization with a Swan-Ganz catheter for measuring hemodynamic parameters. Sampling of arterial blood from a radial artery line for determination of blood gases and ET-1 values was performed simultaneously, after 5 minutes of the first desaturation. RESULTS At rest, arterial ET-1 levels were higher in ILD patients (1.73 +/- 0.37 mgr/mL) than in controls (1.22 +/- 0.15 mgr/mL) ( p < 0.001). Also, the patients with pulmonary hypertension (Pa > 20 mm Hg) presented significantly higher arterial ET-1 levels (1.86 +/- 0.32 mgr/mL) than those without pulmonary hypertension (1.31 +/- 0.13 mgr/mL) ( p < 0.001). Arterial ET-1 levels were significantly correlated with mean pulmonary arterial pressure (PAP) (r = 0.749, p < 0.001), and arterial oxygen partial pressure (PaO2) (r = 0.79, p < 0.001). At sleep, during desaturation, arterial ET-1 levels significantly increased in all patients (2.46 +/- 0.13 mgr/mL) as compared with resting values ( p < 0.001). Arterial ET-1 levels were significantly correlated with PAP (r = 0.657, p < 0.001) and PaO2 (r = 0.93, p < 0.001). CONCLUSIONS According to our study, arterial ET-1 is markedly increased in ILD patients, especially in those with pulmonary hypertension.
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Affiliation(s)
- Georgia Trakada
- University of Patras Medical School, Division of Pulmonology, Laboratory of Sleep, Patras, Greece
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18
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Zhang Y, Oliver JR, Horowitz JD. The Role of Endothelin in Mediating Ischemia/Hypoxia-Induced Atrial Natriuretic Peptide Release. J Cardiovasc Pharmacol 2004; 43:227-33. [PMID: 14716210 DOI: 10.1097/00005344-200402000-00010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of the present study was to investigate the putative role of endothelin (ET) in mediating ischemia/hypoxia-induced ANP release utilizing exogenous ET-1 or ET receptor antagonists (BQ-123 or Bosentan). Isolated rat hearts with non-distended atria were perfused using a Langendorff apparatus and heart rate maintained constant via atrial pacing. Global ischemia was induced either by direct reduction in perfusion or by infusion of exogenous ET-1 (5 x 10(-10) M) for 30 minutes. Perfusion with the ET receptor antagonists, BQ-123 (10(-6) M) or Bosentan (10(-5) M) was initiated 10 minutes before onset of ischemia. Moderate or severe ischemia was induced by reduction (52-61% and 70-82%, respectively) in perfusate flow. Thirty minutes of ischemia/hypoxia (5% O2) was followed by 30 minutes of reperfusion/re-oxygenation. Both moderate and severe ischemia increased ANP release. BQ-123 and Bosentan did not affect basal or ischemia-induced ANP release. Exogenous ET-1 perfusion induced a late increase in ANP release (P < 0.01) that did not exceed the increase in ANP release associated with equivalent direct flow reduction. Hypoxia induced an 8-fold increase in ANP release rate. The ANP release rate returned toward basal levels after re-oxygenation. Bosentan, but not BQ-123, significantly attenuated (P < 0.01) hypoxia-induced ANP release. In conclusion, in this system, ANP release is stimulated by moderate (or severe) ischemia and severe hypoxia independent of change in atrial distension; endogenous ET does not mediate basal and ischemia-induced ANP release; and hypoxia-induced ANP release is partially modulated via interaction with endogenous ET.
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Affiliation(s)
- Yi Zhang
- High Blood Pressure Research Unit, John Curtin School of Medical Research, Australian National University, Canberra, Australia
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19
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Battistini B. Modulation and roles of the endothelins in the pathophysiology of pulmonary embolism. Can J Physiol Pharmacol 2003; 81:555-69. [PMID: 12839267 DOI: 10.1139/y03-017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent research on the endothelins (ETs) and their pathways in acute pulmonary embolism (APE) has led to significant advances in the understanding of this disease. ETs are potent vasoconstrictors and bronchoconstrictors found abundantly in the lung and can be released by stimuli such as endothelial injury, hypoxia, or thrombin, a key product in the coagulation cascade. Many studies using different approaches and methods of inducing pulmonary embolization, both in vitro and in vivo in various species, have mostly shown that ETs play an important role in the pathophysiology of APE. These results were obtained by comparing the hemodynamic data in the presence or absence of various ETs inhibitors, but also by assessing the modulation of the ET-related elements of this system by molecular, cell biology, and pharmacological methods. Based on the current understanding, a mechanism involving the ET pathway in the pathophysiology of APE is proposed for the reader's considerations. We postulate that ETs are primary mediators in APE based on the following: (i) their source from pulmonary endothelial cells where the primary injury takes place; (ii) their direct vasconstrictive, bronchoconstrictive, and promitogenic effects via distinct ET receptors; and (iii) their indirect effects associated with the secondary release of thromboxane and other mediators, which are released from inflammatory cells and platelets, which together can potentiate the overall hemodynamic response, most specifically the pulmonary vascular bed. Such combined effects of ETs on bronchomotor and vasomotor tone in the lung can adversely affect ventilation perfusion matching and lead to severe hypoxemia without causing significant changes in the chest X-ray of these patients. Thus, we may consider ET inhibitors as future current therapeutic agents in patients with PE.
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Affiliation(s)
- Bruno Battistini
- Laval Hospital Research Center, Quebec Heart and Lung Institute, Department of Medicine, Laval University, 2725 Chemin Ste-Foy, Sainte-Foy, QC G1V 4G5, Canada.
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21
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Chow M, Dumont AS, Kassell NF. Endothelin Receptor Antagonists and Cerebral Vasospasm: An Update. Neurosurgery 2002. [DOI: 10.1227/01.neu.0000309108.94215.71] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Michael Chow
- Department of Neurosurgery, University of Virginia, Charlottesville, Virginia
| | - Aaron S. Dumont
- Department of Neurosurgery, University of Virginia, Charlottesville, Virginia
| | - Neal F. Kassell
- Department of Neurosurgery, University of Virginia, Charlottesville, Virginia
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22
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Abstract
Several lines of evidence support a role of immune mechanisms in the pathogenesis of chronic heart failure (CHF). Proinflammatory cytokines (interleukin-1, -2, -6, and tumor necrosis factor) and chemokines are involved in cardiac depression and in the progression of heart failure. Other components believed to be relevant to the pathogenesis of CHF are adhesion molecules, autoantibodies, nitric oxide (NO), and endothelin-1. The origin of the immune activation in patients with CHF is still unknown, however two hypotheses have been proposed on the basis of experimental and clinical data. One suggests that the bowel wall edema leads to bacterial translocation with subsequent endotoxin release and immune activation. The second suggests that the heart in CHF is the main source of cytokines, as is shown by the fact that TNF alpha is produced by the failing myocardium but not by a normal one. No single source of cytokine production (gut or heart) seems sufficient to fully explain the multiple organ involvement and the systemic inflammation of CHF, which is probably related to systemic hypoxia, a potent stimulus for activation of the immune system and for cytokine production. The effort of define the immune system's role has opened new perspectives of therapeutic strategies, such as anti-cytokine drugs, to treat CHF.
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Affiliation(s)
- Daniela Mari
- Department of Internal Medicine, University of Milan, Maggiore Hospital IRCCS, Via Pace 15, 20122 Milan, Italy.
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23
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Rademaker MT, Charles CJ, Espiner EA, Nicholls MG, Richards AM. Long-term adrenomedullin administration in experimental heart failure. Hypertension 2002; 40:667-72. [PMID: 12411460 DOI: 10.1161/01.hyp.0000037132.90640.26] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Short-term administration of adrenomedullin, a recently discovered peptide with potent vasodilator, natriuretic, and aldosterone-inhibitory actions, has beneficial effects in experimental and clinical heart failure. The effects of prolonged adrenomedullin administration have not previously been assessed in this setting. Consequently, in 16 sheep with pacing-induced heart failure, we infused either adrenomedullin (10 ng/kg per minute; n=8) or a vehicle control (Hemaccel; n=8) for 4 days. Compared with control data, infusion of adrenomedullin persistently increased circulating levels of the peptide (by approximately 9.5 pmol/L; P<0.001), in association with prompt (15 minutes) and sustained (4 days) increases in cardiac output (day 4, 27%), and reductions in peripheral resistance (30%), mean arterial pressure (13%), and left atrial pressure (24%; all, P<0.001). Adrenomedullin also significantly enhanced urinary sodium excretion (day 4, 3-fold; P<0.05), creatinine excretion (1.2-fold; P<0.001), and creatinine clearance (1.4-fold; P<0.001) over the 4 days of treatment, whereas urine volume and cAMP excretion tended to be elevated (both, 0.1>P>0.05). Plasma renin activity was increased (P<0.05), whereas aldosterone levels were reduced in a sustained fashion (P<0.01). Plasma endothelin rose transiently (hours 1 to 6) after initiation of treatment (P<0.05). Despite substantial cardiac unloading, plasma concentrations of the natriuretic peptides were not significantly different from control. In conclusion, long-term administration of adrenomedullin induces pronounced and sustained cardiovascular and renal effects in experimental heart failure, including reductions in cardiac preload and afterload, as well as augmentation of cardiac output, sodium excretion, and glomerular filtration. These findings support the concept of adrenomedullin as a protective hormone during hemodynamic compromise with therapeutic potential in heart failure.
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Affiliation(s)
- Miriam T Rademaker
- Christchurch Cardioendocrine Research Group, Department of Medicine, The Christchurch School of Medicine, Christchurch, New Zealand.
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24
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Aaronson PI, Robertson TP, Ward JPT. Endothelium-derived mediators and hypoxic pulmonary vasoconstriction. Respir Physiol Neurobiol 2002; 132:107-20. [PMID: 12126699 DOI: 10.1016/s1569-9048(02)00053-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The vascular endothelium synthesises, metabolises or converts a multitude of vasoactive mediators, and plays a vital role in the regulation of pulmonary vascular resistance. Its role in hypoxic pulmonary vasoconstriction (HPV) is however controversial. Although HPV has been demonstrated in both pulmonary arteries where the endothelium has been removed and isolated pulmonary artery smooth muscle cells, many reports have shown either partial or complete dependence on an intact endothelium for sustained HPV (> approximately 20 min). However, despite many years of study no known endothelium-derived mediator has yet been unequivocally shown to be essential for HPV, although several may either facilitate the response or act as physiological brakes to limit the extent of HPV. In this article we review the evidence for and against the role of specific endothelium-derived mediators in HPV. We make the case for a facilitatory or permissive function of the endothelium, that in conjunction with a rise in smooth muscle intracellular Ca(2+) initiated by a mechanism intrinsic to smooth muscle, allows the development of sustained HPV. In particular, we propose that in response to hypoxia the pulmonary vascular endothelium releases an as yet unidentified agent that causes Ca(2+) sensitisation in the smooth muscle.
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Affiliation(s)
- Philip I Aaronson
- Department of Respiratory Medicine and Allergy, Centre for Cardiovascular Biology and Medicine, Guy's, King's and St Thomas' School of Medicine, 5th Floor Thomas Guy House, King's College London, Guy's Campus, London SE1 9RT, UK
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25
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Ono K, Matsumori A. Endothelin antagonism with bosentan: current status and future perspectives. CARDIOVASCULAR DRUG REVIEWS 2002; 20:1-18. [PMID: 12070530 DOI: 10.1111/j.1527-3466.2002.tb00078.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Endothelin receptor antagonists have been proposed for the treatment of a variety of disorders in which the endothelins may act as pathogenic mediators, such as hypertension, congestive heart failure, and cerebral vasospasm. Bosentan is a nonpeptide competitive antagonist, which can be a good tool for studying the endothelin system. It is specific for the endothelin system and blocks the actions of endothelin at both mammalian receptors (A and B). Bosentan has recently moved into Phase III clinical trial. This review will attempt to overview the experimental and clinical effects of bosentan.
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Affiliation(s)
- Koh Ono
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto Japan 606-8297
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26
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Huang KL, Wu CP, Kang BH, Lin YC. Chronic hypoxia attenuates nitric oxide-dependent hemodynamic responses to acute hypoxia. J Biomed Sci 2002; 9:206-12. [PMID: 12065895 DOI: 10.1007/bf02256067] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Alterations in the nitric oxide (NO) pathway have been implicated in the pathogenesis of chronic hypoxia-induced pulmonary hypertension. Chronic hypoxia can either suppress the NO pathway, causing pulmonary hypertension, or increase NO release in order to counteract elevated pulmonary arterial pressure. We determined the effect of NO synthase inhibitor on hemodynamic responses to acute hypoxia (10% O(2)) in anesthetized rats following chronic exposure to hypobaric hypoxia (0.5 atm, air). In rats raised under normoxic conditions, acute hypoxia caused profound systemic hypotension and slight pulmonary hypertension without altering cardiac output. The total systemic vascular resistance (SVR) decreased by 41 +/- 5%, whereas the pulmonary vascular resistance (PVR) increased by 25 +/- 6% during acute hypoxia. Pretreatment with N(omega)-nitro-L-arginine methyl ester (L-NAME; 25 mg/kg) attenuated systemic vasodilatation and enhanced pulmonary vasoconstriction. In rats with prior exposure to chronic hypobaric hypoxia, the baseline values of mean pulmonary and systemic arterial pressure were significantly higher than those in the normoxic group. Chronic hypoxia caused right ventricular hypertrophy, as evidenced by a greater weight ratio of the right ventricle to the left ventricle and the interventricular septum compared to the normoxic group (46 +/- 4 vs. 28 +/- 3%). In rats which were previously exposed to chronic hypoxia (half room air for 15 days), acute hypoxia reduced SVR by 14 +/- 6% and increased PVR by 17 +/- 4%. Pretreatment with L-NAME further inhibited the systemic vasodilatation effect of acute hypoxia, but did not enhance pulmonary vasoconstriction. Our results suggest that the release of NO counteracts pulmonary vasoconstriction but lowers systemic vasodilatation on exposure to acute hypoxia, and these responses are attenuated following adaptation to chronic hypoxia.
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Affiliation(s)
- Kun-Lun Huang
- Department of Critical Care Medicine, Tri-Service General Hospital, Taipei, Taiwan, ROC.
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27
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Wroblewski Lissin L, Cooke JP. Maintaining the endothelium: preventive strategies for vessel integrity. PREVENTIVE CARDIOLOGY 2002; 3:172-177. [PMID: 11834938 DOI: 10.1111/j.1520-037x.2000.803811.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The endothelium is a diaphanous membrane, only one cell layer thick, that lines all of our blood vessels. Despite its apparent fragility, it exerts profound control over vascular tone, structure, and interaction with circulating blood elements. One of the factors that the endothelium synthesizes is nitric oxide, which is the most potent endogenous vasodilator known. In addition to its blood flow regulating effects, nitric oxide also inhibits key processes in atherosclerosis, including monocyte adherence, platelet aggregation, and proliferation of vascular smooth muscle cells. Nitric oxide synthesis is impaired, and its degradation is accelerated, in many of the conditions associated with atherosclerosis, including hypercholesterolemia. Restoration of nitric oxide synthesis and activity in these disorders can improve blood flow, relieve symptoms, and perhaps reduce the progression of atherosclerosis (part 1 of 2 parts). (c) 2000 by CHF, Inc.
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Affiliation(s)
- L Wroblewski Lissin
- Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, CA 94305
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28
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Lissin LW, Cooke JP. Maintaining the endothelium: preventive strategies for vessel integrity. PREVENTIVE CARDIOLOGY 2002; 4:28-37. [PMID: 11828196 DOI: 10.1111/j.1520-037x.2001.90810.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelium is a diaphanous membrane, only one cell layer thick, that lines all of our blood vessels. Despite its apparent fragility, it exerts profound control over vascular tone, structure, and intersection with circulating blood elements. One of the factors that the endothelium synthesizes is nitric oxide, which is the most potent endogenous vasodilator known. In addition to its blood flow regulating effects, nitric oxide also inhibits key processes in atherosclerosis, including monocyte adherence, platelet aggregation, and proliferation of vascular smooth muscle cells. Nitric oxide synthesis is impaired, and its degradation is accelerated, in many of the conditions associated with atherosclerosis, including hypercholesterolemia. Restoration of nitric oxide synthesis and activity in these disorders can improve blood flow, relieve symptoms, and perhaps reduce the progression of atherosclerosis.(c) 2001 by CHF, Inc.
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Affiliation(s)
- L W Lissin
- Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, CA
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29
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Lüscher TF, Spieker LE, Noll G, Cosentino F. Vascular effects of newer cardiovascular drugs: focus on nebivolol and ACE-inhibitors. J Cardiovasc Pharmacol 2001; 38 Suppl 3:S3-11. [PMID: 11811390 DOI: 10.1097/00005344-200112003-00002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Alterations in the function and structure of the blood vessel wall account for most clinical events in the coronary and cerebrovascular circulation such as myocardial infarction and stroke. Cardiovascular drugs may exert beneficial effects on the vascular wall both at the level of the endothelium and vascular smooth muscle cells. Therefore, endothelial mediators, in particular nitric oxide (NO) and endothelin (ET), are of special interest. Drugs can modulate the expression and actions of NO, a vasodilator with antiproliferative and antithrombotic properties, and of ET, a potent vasoconstrictor and proliferative mitogenic agent. The most successful drugs in this context are statins and angiotensin-converting enzyme (ACE)-inhibitors. While statins increase the expression of NO synthase. ACE-inhibitors increase the release of NO via bradykinin-mediated mechanisms. Antioxidant properties of drugs are also important, as oxidative stress is crucial in atherosclerotic vascular disease. These properties may explain part of the effects of calcium antagonists and ACE-inhibitors. Indeed, angiotensin II stimulates NAD(P)H oxidases responsible for the formation of superoxide, which inactivates NO. ACE-Inhibitors thus increase the bioavailability of NO. Newer cardiovascular drugs such as nebivolol are able to directly stimulate NO release from the endothelium both in isolated arteries and in the human forearm circulation. ET receptor antagonists may exert beneficial effects in the vessel wall by preventing the effects of ET at its receptors and by reducing ET production. In summary, cardiovascular drugs have important effects on the vessel wall, which may be clinically relevant for the prevention and treatment of cardiovascular disease.
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Affiliation(s)
- T F Lüscher
- Division of Cardiology, University Hospital, Zürich, Switzerland
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30
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Spieker LE, Noll G, Ruschitzka FT, Lüscher TF. Endothelin A receptor antagonists in congestive heart failure: blocking the beast while leaving the beauty untouched? Heart Fail Rev 2001; 6:301-15. [PMID: 11447305 DOI: 10.1023/a:1011456309039] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Congestive heart failure (CHF) is a disease process characterized by impaired left ventricular function, increased peripheral and pulmonary vascular resistance and reduced exercise tolerance and dyspnea. Thus, mediators involved in the control of myocardial function and vascular tone may be involved in its pathophysiology. The family of endothelins (ET) consists of four closely related peptides, ET-1, ET-2, ET-3, and ET-4, which cause vasoconstriction, cell proliferation, and myocardial effects through activation of ET(A) receptors. In contrast, endothelial ET(B) receptors mediate vasodilation via release of nitric oxide and prostacyclin. In addition, ET(B) receptors in the lung are a major pathway for the clearance of ET-1 from plasma. Thus, infusion of an ET(A) receptor antagonist into the brachial artery in healthy humans leads to vasodilation whereas infusion of an ET(B) receptor antagonist causes vasoconstriction. ET-1 plasma levels are elevated in CHF and correlate both with the hemodynamic severity and with symptoms. Plasma levels of ET-1 and its precursor, big ET-1, are strong independent predictors of death in patients after myocardial infarction and with CHF. ET-1 contributes to increased systemic and pulmonary vascular resistance, vascular dysfunction, myocardial ischemia, and renal impairment in CHF. Selective ET(A) as well as combined ET(A/B) receptor antagonists have been studied in patients with CHF showing impressive hemodynamic improvements (i.e. reduced peripheral vascular and pulmonary resistance as well as increased cardiac output). These results indicate that ET receptor antagonists indeed have a potential to improve hemodynamics, symptoms, and potentially prognosis of CHF which still carries a high mortality.
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Affiliation(s)
- L E Spieker
- Cardiology, University Hospital, Zürich, Switzerland
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31
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Trakada G, Marangos M, Spiropoulos K. Mechanisms of endothelin-1 elevation in chronic obstructive pulmonary disease patients with nocturnal oxyhemoglobin desaturation. Respiration 2001; 68:134-9. [PMID: 11287826 DOI: 10.1159/000050482] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Nonapneic, oxyhemoglobin desaturation associated with sleep has been described in patients with chronic obstructive pulmonary disease (COPD). Hypoxemia stimulates endothelin-1 (ET-1) secretion. Once released, ET-1 can act locally to elicit sustained pulmonary artery vasoconstriction, bronchoconstriction and activation of alveolar macrophages. OBJECTIVE The aim of this study was to examine a possible correlation between ET-1 levels and nocturnal, nonapneic, oxyhemoglobin desaturation during sleep, in patients with COPD. METHODS We examined 48 COPD patients with formal polysomnography (EEG, ECG, airflow, respiratory muscle movement, oximeter) to detect the presence of nocturnal, nonapneic, oxyhemoglobin desaturation. Twelve of them were disqualified because of inadequate sleep or sleep apnea syndrome. Nineteen of them desaturated below a baseline sleep saturation of 90% for 5 min or more, reaching a nadir saturation of at least 85%. We collected arterial samples to measure ET-1 levels, after 5 min of the first period of desaturation, in each of the 19 patients. We also collected arterial samples in the morning, before the study, to measure baseline ET-1 levels in all patients. RESULTS Baseline arterial ET-1 levels during the day were very significantly higher in 'desaturator' COPD patients (2.058 +/- 0.252 pg/ml) compared to 'non-desaturator' COPD patients (1.382 +/- 0.159 pg/ml; p < 0.001). Also in 'desaturator' COPD patients ET-1, levels during the night were significantly higher (4.297 +/- 1.107 pg/ml) compared to those during the day (p < or = 0.001) and a significant negative correlation was observed between ET-1 levels and degree of desaturation (p < 0.0001, r = 0.9305). CONCLUSIONS According to our study we can conclude that (1) ET-1 levels are significantly higher in 'desaturator' COPD patients both during the day and during the night, and (2) ET-1 levels correlate negatively significant with the degree of the oxyhemoglobin desaturation. These findings are consistent with the hypothesis that ET-1 plays a very important role in the pathophysiological manifestations of COPD patients.
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Affiliation(s)
- G Trakada
- Department of Internal Medicine, Division of Pulmonology, University of Patras Medical School, Patras, Greece
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32
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Benamou AE, Marlin DJ, Lekeux P. Endothelin in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia. Equine Vet J 2001; 33:345-53. [PMID: 11469766 DOI: 10.2746/042516401776249462] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Elevated concentrations of endothelin (ET), a potent endothelium-derived vasoactive peptide, have been reported in a number of pathophysiological conditions associated with pulmonary hypertension, both in the horse and other species. We have previously shown, both in vitro and in vivo, that the pulmonary and systemic vascular response to exogenous ET is mediated predominantly via ET(A) receptors. Our hypothesis in the present study was that ET is involved in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia. In this study, we investigated the effects of a selective ET(A) receptor antagonist on hypoxic pulmonary hypertension in the mature horse. Horses were exposed to a 10 min period of hypoxia (F(I)O2 approximately 0.11) on 2 occasions, with and without pretreatment with the selective ET(A) receptor antagonist TBC11251 (10 mg/kg bwt i.v.). Hypoxia increased mean pulmonary artery pressure (PAP) from 18.3+/-0.9 (mean +/- s.e. normoxia) to 28.0+/-0.8 mmHg (hypoxia) in the session without ET(A) receptor antagonism. Carotid arterial pressure (CAP) also increased progressively throughout the period of hypoxic challenge and at the end was 153+/-5 mmHg (hypoxia) compared to during normoxia (140+/-5 mmHg). There was no significant overall effect of ET(A) receptor antagonism on the haemodynamic or ventilatory responses to acute hypoxia. However, between 5 and 10 min of hypoxia there was a trend for the mean PAP to diverge in the 2 treatments, which just failed to reach significance at 10 min of hypoxia (P = 0.053). In conclusion, this study describes the haemodynamic and ventilatory changes in response to a period of acute hypoxia in the adult horse. The results do not support a role for ET as a mediator of acute HPV in the horse, but suggest that it may be involved as a modulator or in the slower (>10 min) phase of HPV.
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Affiliation(s)
- A E Benamou
- Centre for Equine Studies, Animal Health Trust, Kentford, Newmarket, UK
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Liu Q, Sham JS, Shimoda LA, Sylvester JT. Hypoxic constriction of porcine distal pulmonary arteries: endothelium and endothelin dependence. Am J Physiol Lung Cell Mol Physiol 2001; 280:L856-65. [PMID: 11290508 DOI: 10.1152/ajplung.2001.280.5.l856] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine the role of endothelium in hypoxic pulmonary vasoconstriction (HPV), we measured vasomotor responses to hypoxia in isolated seventh-generation porcine pulmonary arteries < 300 microm in diameter with (E+) and without endothelium. In E+ pulmonary arteries, hypoxia decreased the vascular intraluminal diameter measured at a constant transmural pressure. These constrictions were complete in 30-40 min; maximum at PO(2) of 2 mm Hg; half-maximal at PO(2) of 40 mm Hg; blocked by exposure to Ca(2+)-free conditions, nifedipine, or ryanodine; and absent in E+ bronchial arteries of similar size. Hypoxic constrictions were unaltered by indomethacin, enhanced by indomethacin plus N(G)-nitro-L-arginine methyl ester, abolished by BQ-123 or endothelial denudation, and restored in endothelium-denuded pulmonary arteries pretreated with 10(-10) M endothelin-1 (ET-1). Given previous demonstrations that hypoxia caused contractions in isolated pulmonary arterial myocytes and that ET-1 receptor antagonists inhibited HPV in intact animals, our results suggest that full in vivo expression of HPV requires basal release of ET-1 from the endothelium to facilitate mechanisms of hypoxic reactivity in pulmonary arterial smooth muscle.
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Affiliation(s)
- Q Liu
- Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA
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Spieker LE, Noll G, Ruschitzka FT, Lüscher TF. Endothelin receptor antagonists in congestive heart failure: a new therapeutic principle for the future? J Am Coll Cardiol 2001; 37:1493-505. [PMID: 11345356 DOI: 10.1016/s0735-1097(01)01210-4] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Congestive heart failure (CHF) is characterized by impaired left ventricular function, increased peripheral and pulmonary vascular resistance and reduced exercise tolerance and dyspnea. Thus, mediators involved in the control of myocardial function and vascular tone may be involved in its pathophysiology. The family of endothelins (ET) consists of four closely related peptides, ET-1, ET-2, ET-3 and ET-4, which cause vasoconstriction, cell proliferation and myocardial effects through activation of ETA receptors. In contrast, endothelial ETB receptors mediate vasodilation via release of nitric oxide and prostacyclin. In addition, ETB receptors in the lung are a major pathway for the clearance of ET-1 from plasma. Thus, infusion of an ETA-receptor antagonist into the brachial artery in healthy humans leads to vasodilation, whereas infusion of an ETB-receptor antagonist causes vasoconstriction. Endothelin-1 plasma levels are elevated in CHF and correlate both with hemodynamic severity and symptoms. Plasma levels of ET-1 and its precursor, big ET-1, are strong independent predictors of death after myocardial infarction as well as in CHF. Endothelin-1 contributes to increased systemic and pulmonary vascular resistance, vascular dysfunction, myocardial ischemia and renal impairment in CHF. Selective ETA, as well as combined ETA/B-receptor antagonists, have been studied in patients with CHF, and their use has shown impressive hemodynamic improvement (i.e., reduced peripheral vascular and pulmonary resistance as well as increased cardiac output). These results indicate that ET-receptor antagonists, indeed, have a potential to improve hemodynamics, symptoms and, potentially, prognosis in patients with CHF, which still carries a high mortality.
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Affiliation(s)
- L E Spieker
- Cardiovascular Center, Cardiology Department, University Hospital, Zürich, Switzerland
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35
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Enseleit F, Hürlimann D, Lüscher TF. Vascular protective effects of angiotensin converting enzyme inhibitors and their relation to clinical events. J Cardiovasc Pharmacol 2001; 37 Suppl 1:S21-30. [PMID: 11392475 DOI: 10.1097/00005344-200109011-00004] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Endothelial cells are a rich source of a variety of vasoactive substances, which either cause vasodilation or vasoconstriction. Important endothelium-derived vasodilators are prostacyclin, bradykinin, nitric oxide and endothelium-derived hyperpolarizing factor. In particular, nitric oxide inhibits cellular growth and migration. In concert with prostacyclin. nitric oxide exerts potent anti-atherogenic and thromboresistant properties by preventing platelet aggregation and cell adhesion. Endothelium-derived contracting factors include the 21 amino acid peptide endothelin (ET). vasoconstrictor prostanoids such as thromboxane A2 and prostaglandin H2, as well as free radicals and components of the renin angiotensin system. In hypertension, elevated blood pressure transmits into cardiovascular disease by causing endothelial dysfunction. Hence, modem therapeutic strategies in human hypertension focus on preserving or restoring endothelial integrity. Angiotensin converting enzyme (ACE) inhibitors are a primary candidate for that concept as they inhibit the circulating and local renin angiotensin system. Angiotensin converting enzyme is an endothelial enzyme which converts angiotensin-I (A-I) into angiotensin-II (A-II). This effect of the ACE inhibitor prevents direct effects of angiotensin-II such as vasoconstriction and proliferation in the vessel wall but also prevents activation of the ET system and of plasminogen activator inhibitor. Furthermore, inhibition of ACE prolongs the half-life of bradykinin and stabilizes bradykinin receptors linked to the formation of nitric oxide and prostacyclin. In isolated arteries ACE inhibitors prevent the contractions induced by angiotensin II and enhance relaxation induced by bradykinin. Chronic treatment of experimental hypertension with ACE inhibitors normalizes endothelium-dependent relaxation to acetylcholine and other agonists. In addition, the dilator effects of exogenous nitric oxide donors are enhanced, at least in certain models of hypertension. In humans with essential hypertension ACE inhibitors augment endothelium-dependent relaxation to bradykinin, while those to acetylcholine remain unaffected, at least in the time frame of the published studies, i.e. 3-6 months. In patients with coronary artery disease, however, paradoxical vasoconstriction to acetylcholine is markedly reduced after 6 months of ACE inhibition. After myocardial infarction ACE inhibitors reduce the development of overt heart failure, the occurrence of reinfarction and cardiovascular death in hypertensive patients. These effects have also been demonstrated in a subgroup analysis of the SOLVD (Studies of Left Ventricular Dysfunction) trial. Thus, in summary, ACE inhibitors are an important class of drugs providing cardiovascular protection in patients with increased cardiovascular risk.
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Affiliation(s)
- F Enseleit
- Cardiology, University Hospital Zürich, Switzerland
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Spieker LE, Noll G, Lüscher TF. Therapeutic potential for endothelin receptor antagonists in cardiovascular disorders. Am J Cardiovasc Drugs 2001; 1:293-303. [PMID: 14728028 DOI: 10.2165/00129784-200101040-00007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelins are synthesized in vascular endothelial and smooth muscle cells, as well as in neural, renal, pulmonal, and inflammatory cells. These peptides are converted by endothelin-converting enzymes (ECE-1 and -2) from 'big endothelins' originating from large preproendothelin peptides cleaved by endopeptidases. Endothelin (ET)-1 has major influence on the function and structure of the vasculature as it favors vasoconstriction and cell proliferation through activation of specific ET(A) and ET(B) receptors on vascular smooth muscle cells. In contrast, ET(B )receptors on endothelial cells cause vasodilation via release of nitric oxide (NO) and prostacyclin. Additionally, ET(B) receptors in the lung are a major pathway for the clearance of ET-1 from plasma. Indeed, ET-1 contributes to the pathogenesis of important disorders as arterial hypertension, atherosclerosis, and heart failure. In patients with atherosclerotic vascular disease (as well as in many other disease states), ET-1 levels are elevated and correlate with the number of involved sites. In patients with acute myocardial infarction, they correlate with 1-year prognosis. ET receptor antagonists have been widely studied in experimental models of cardiovascular disease. In arterial hypertension, they prevent vascular and myocardial hypertrophy. Experimentally, ET receptor blockade also prevents endothelial dysfunction and structural vascular changes in atherosclerosis due to hypercholesterolemia. In experimental myocardial ischemia, treatment with an ET receptor antagonist reduced infarct size and prevented left ventricular remodeling after myocardial infarction. Most impressively, treatment with the selective ET(A) receptor antagonist BQ123 significantly improved survival in an experimental model of heart failure. In many clinical conditions, such as congestive heart failure, both mixed ET(A/B )as well as selective ET(A) receptor antagonism ameliorates the clinical status of patients, i.e. symptoms and hemodynamics. A randomized clinical trial showed that a mixed ET(A/B) receptor antagonist effectively lowered arterial blood pressure in patients with arterial hypertension. In patients with primary pulmonary hypertension or pulmonary hypertension related to scleroderma, treatment with a mixed ET(A/B) receptor antagonist resulted in an improvement in exercise capacity. ET receptor blockers thus hold the potential to improve the outcome in patients with various cardiovascular disorders. Randomized clinical trials are under way to evaluate the effects of ET receptor antagonism on morbidity and mortality.
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Affiliation(s)
- L E Spieker
- Cardiovascular Centre, Division of Cardiology, University Hospital and Cardiovascular Research, Institute of Physiology, Zürich, Switzerland
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37
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Salmon M, Liu YC, Mak JC, Rousell J, Huang TJ, Hisada T, Nicklin PL, Chung KF. Contribution of upregulated airway endothelin-1 expression to airway smooth muscle and epithelial cell DNA synthesis after repeated allergen exposure of sensitized Brown-Norway rats. Am J Respir Cell Mol Biol 2000; 23:618-25. [PMID: 11062140 DOI: 10.1165/ajrcmb.23.5.3909] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Endothelin-1 is a potent bronchoconstrictor peptide with pro-inflammatory and growth-promoting properties. After exposure of sensitized Brown-Norway rats to six repeated ovalbumin exposures, there was an increase in pro-endothelin (ET)-1 messenger RNA compared with saline-exposed control rats 24 h after the final exposure (P < 0.01). ET-1 immunoreactivity was increased sixfold in the bronchial epithelium of the larger conducting airways in the repeated allergen-exposed rats (P < 0.001). After repeated allergen exposure, there were increased rates of DNA synthesis in the airway smooth muscle (ASM) cells (P < 0.001) and epithelial cells (P < 0. 001) compared with saline-exposed controls, as measured by bromodeoxyuridine incorporation. Treatment with a dual endothelin A and B (ET(A+B)) receptor antagonist caused a significant attenuation in both ASM (P < 0.001) and epithelial cell (P < 0.001) bromodeoxyuridine incorporation compared with the allergen-challenged and vehicle-treated group. The dual ET(A+B) antagonist attenuated eosinophil recruitment into the airways (P < 0. 05) but had no significant effect on increased bronchial reactivity to acetylcholine in allergen-exposed rats. Increased levels of ET-1 in the airways may contribute to inflammation and ASM and epithelial cell DNA synthesis after repeated allergen exposure. Such processes may underlie increased proliferation of resident cells leading to airway wall remodeling in asthmatics.
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Affiliation(s)
- M Salmon
- National Heart & Lung Institute, Imperial College School of Medicine, London, United Kingdom
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38
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Lal H, Yu Q, Ivor Williams K, Woodward B. Hypoxia augments conversion of big-endothelin-1 and endothelin ET(B) receptor-mediated actions in rat lungs. Eur J Pharmacol 2000; 402:101-10. [PMID: 10940363 DOI: 10.1016/s0014-2999(00)00499-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have examined the effect of endothelin-1, sarafotoxin-6C, big-endothelin-1 and other agents on perfused lungs from chronically hypoxic rats. Increases in pulmonary perfusion pressure induced by big-endothelin-1, endothelin-1, phenylephrine and potassium chloride were enhanced in hypoxic lungs, while the constrictor action of sarafotoxin-6C was not increased. When basal pulmonary perfusion pressure was raised, low doses of endothelin-1 and sarafotoxin-6C produced decreases in pulmonary perfusion pressure which were significantly greater in chronically hypoxic lungs, whereas responses to sodium nitroprusside were unchanged. Endothelin ET(B) receptor-mediated bronchoconstrictor responses were also potentiated in hypoxic lungs, whereas responses to carbachol were not. In hypoxic lungs, conversion of big-endothelin-1 to endothelin-1 was significantly increased. These data provide evidence for a generalised increase in vasomotor activity in chronically hypoxic lungs, and a more selective increase in endothelin ET(B) receptor-mediated vasodilator and bronchoconstrictor responses. Hypoxia also augments the conversion of big-endothelin-1 to endothelin-1.
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Affiliation(s)
- H Lal
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
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Victorino GP, Wisner DH, Tucker VL. Basal release of endothelin-1 and the influence of the ETB receptor on single vessel hydraulic permeability. THE JOURNAL OF TRAUMA 2000; 49:314-9. [PMID: 10963545 DOI: 10.1097/00005373-200008000-00020] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Endothelin-1 (ET-1) has a direct permeability decreasing effect on the microvasculature. The present study was designed to test the hypothesis that this effect is mediated via the endothelin B (ETB) receptor located on the microvascular endothelium and to determine whether basal microvascular permeability is dependent on constitutive release of ET-1. To isolate the direct effect of ET-1, experiments were conducted under conditions in which hydraulic and oncotic pressures were controlled. METHODS Postcapillary venules in the rat mesentery were perfused in situ, and paired measurements of hydraulic permeability (Lp) were obtained using the modified Landis micro-occlusion method. Lp measured after a 15-minute perfusion with the ETB receptor blocker BQ-788 (1 micromol/L) was compared with measures of Lp obtained after perfusion with a combined mixture of BQ-788 and ET-1 (80 pmol/L) (n = 6). In addition, the effect of basal endogenous ET-1 was tested by measuring the effects of BQ-788 perfusion on Lp (n = 6). RESULTS Units for Lp are mean +/- SE x 10(-8) cm x s(-1) cm H2O(-1). ETB receptor blockade prevented any decrease in Lp induced by ET-1 (BQ-788 alone = 7.9 +/- 0.7; BQ-788 + ET-1 = 8.2 +/- 0.8;p = 0.5). Under basal conditions and in the absence of exogenous ET-1, ETB receptor blockade led to a significant increase in Lp from 6.8 +/- 0.9 to 9.7 +/- 1.2 (p = 0.001). CONCLUSION Decreases in microvascular permeability in single postcapillary venules after the administration of ET-1 are mediated via the ETB receptor. Constitutive release of ET-1 from the microvascular endothelium also plays a role in maintaining basal levels of permeability. These findings suggest important roles for ET-1 in maintaining and modulating microvascular permeability.
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Affiliation(s)
- G P Victorino
- Department of Surgery, University of California, Davis, Health System, Sacramento, USA
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Tilton RG, Munsch CL, Sherwood SJ, Chen SJ, Chen YF, Wu C, Block N, Dixon RA, Brock TA. Attenuation of pulmonary vascular hypertension and cardiac hypertrophy with sitaxsentan sodium, an orally active ET(A) receptor antagonist. Pulm Pharmacol Ther 2000; 13:87-97. [PMID: 10799286 DOI: 10.1006/pupt.2000.0237] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Effects of sitaxsentan (TBC11251), an orally active, highly selective antagonist of endothelin A receptors, were examined on the development and maintenance of pulmonary hypertension, pulmonary vascular remodeling, and cardiac hypertrophy in the rat. The pulmonary vasoconstrictor response to acute hypoxia (10% O(2)for 90 min) was prevented with sitaxsentan (5 mg/kg infused iv 10 min prior to the onset of hypoxia) while BQ-788 (a specific endothelin B receptor antagonist) was without effect. The same dose of sitaxsentan delivered iv 50 min after the onset of hypoxia reversed the established pulmonary vasoconstriction. In a 2-week model of hypoxia using 10% O(2), treatment with sitaxsentan (15 mg/kg per day in drinking water) attenuated pulmonary hypertension and the associated right ventricular hypertrophy, and prevented the remodeling of small pulmonary arteries (50-100 microM) without affecting systemic arterial blood pressure or heart rate. Institution of sitaxsentan treatment (15 and 30 mg/kg per day in drinking water) for 4 weeks after 2 weeks of untreated hypoxia produced a significant, dose dependent reversal of the established pulmonary hypertension, right heart hypertrophy, and pulmonary vascular remodeling despite continued hypoxic exposure. Sitaxsentan blocked increased plasma endothelin levels in the prevention protocol but did not affect the established elevated levels in the intervention study. Sitaxsentan dose dependently (10 and 50 mg/kg per day in the drinking water) attenuated right ventricular systolic pressure, right heart hypertrophy, and pulmonary vascular remodeling observed 3 weeks after a single subcutaneous injection of monocrotaline. These findings support the hypothesis that endothelin-1 plays a significant role in the development of pulmonary hypertension, pulmonary vascular remodeling, and the associated cardiac hypertrophy, and further suggest that specific endothelin-A receptor blockade may be useful in the treatment of pulmonary hypertension of diverse etiologies.
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Affiliation(s)
- R G Tilton
- Department of Cell Biology, Texas Biotechnology Corporation, Houston, Texas 77030, USA.
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41
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Medbø S, Beisvag V, Tølløfsrud PA, Ellingsen Ø, Wright MS. Attenuated endothelin-1 mRNA expression with endothelin-1 receptor blockade during hypoxaemia and reoxygenation in newborn piglets. Acta Paediatr 2000; 89:698-702. [PMID: 29265524 DOI: 10.1111/j.1651-2227.2000.tb00368.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/1999] [Accepted: 12/23/1999] [Indexed: 11/30/2022]
Abstract
We investigated the cause of decreased plasma endothelin-1 (ET-1) during hypoxaemia and reoxygenation in newborn piglets subjected to simultaneous blocking of the ET-1 receptors. Changes in plasma ET-1 and prepro-ET-1 mRNA expression in the main pulmonary artery and the left lower lobe in the lung were studied in 1-2-d-old piglets. Ten minutes prior to hypoxaemia, the hypoxaemia group (n = 10) was given saline, two groups (both n = 9) were given 1 and 5 mg/kg i.v. SB 217242 (an ET-1 receptor antagonist). Two groups served as normoxic controls, with and without SB 217242 5 mg/kg i.v. Hypoxaemia was induced by ventilating with 8% O2 until base excess was 20mmol/l or mean arterial blood pressure was < 20mmHg. Reoxygenation was performed for 2h with room air. During hypoxaemia, plasma ET-1 decreased in the hypoxaemia group, remained unchanged in the 1-mg group and increased in the 5-mg group. At the end of reoxygenation, plasma ET-1 was above baseline in the 1-mg and 5-mg groups. In the pulmonary artery, the hypoxaemia group showed 2- to 5-fold higher prepro-ET-1 mRNA expression compared to all the other groups (p < 0.05). There were trends for higher prepro-ET-1 mRNA expression in pulmonary tissue in the hypoxaemia group compared to the two receptor-blocking groups (p < 0.07). CONCLUSIONS We conclude that hypoxaemia and reoxygenation increase prepro-ET-1 mRNA expression in the pulmonary artery in newborn piglets. These observations suggest that the half-life of ET-1 is decreased during hypoxaemia and reoxygenation in newborn piglets.
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Affiliation(s)
- S Medbø
- Department of Paediatric Research The National Hospital, Oslo, NorwayInstitute for Surgical Research The National Hospital, Oslo, NorwaySection of Neonatology The National Hospital, Oslo, NorwayDepartment of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Medical Technology Centre, Trondheim, Norway
| | - V Beisvag
- Department of Paediatric Research The National Hospital, Oslo, NorwayInstitute for Surgical Research The National Hospital, Oslo, NorwaySection of Neonatology The National Hospital, Oslo, NorwayDepartment of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Medical Technology Centre, Trondheim, Norway
| | - P A Tølløfsrud
- Department of Paediatric Research The National Hospital, Oslo, NorwayInstitute for Surgical Research The National Hospital, Oslo, NorwaySection of Neonatology The National Hospital, Oslo, NorwayDepartment of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Medical Technology Centre, Trondheim, Norway
| | - Ø Ellingsen
- Department of Paediatric Research The National Hospital, Oslo, NorwayInstitute for Surgical Research The National Hospital, Oslo, NorwaySection of Neonatology The National Hospital, Oslo, NorwayDepartment of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Medical Technology Centre, Trondheim, Norway
| | - M S Wright
- Department of Paediatric Research The National Hospital, Oslo, NorwayInstitute for Surgical Research The National Hospital, Oslo, NorwaySection of Neonatology The National Hospital, Oslo, NorwayDepartment of Physiology and Biomedical Engineering, Norwegian University of Science and Technology, Medical Technology Centre, Trondheim, Norway
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Loer SA, Kalweit G, Tarnow J. Effects of ventilation and nonventilation on pulmonary venous blood gases and markers of lung hypoxia in humans undergoing total cardiopulmonary bypass. Crit Care Med 2000; 28:1336-40. [PMID: 10834675 DOI: 10.1097/00003246-200005000-00013] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess the effects of lung oxygenation and ventilation vs. lung collapse on pulmonary markers of lung hypoxia. DESIGN A prospective, nonrandomized, nonblinded comparative study. SETTING University department of anesthesiology and cardiothoracic surgery. SUBJECTS Twelve adult patients undergoing coronary bypass grafting requiring total cardiopulmonary bypass. INTERVENTIONS Single lung ventilation during total cardiopulmonary bypass (tidal volume, 150 mL; respiratory rate, 6 breaths/min; inspiratory oxygen fraction, 0.5) while the contralateral lung was allowed to collapse completely without oxygenation. MEASUREMENTS AND MAIN RESULTS At the beginning and at the end of total cardiopulmonary bypass (duration, 59-65 mins), blood was aspirated from the right and left pulmonary veins and the radial artery for measurement of blood gases and concentrations of endothelin-1, big-endothelin, thromboxane B2, lactate, and lactate dehydrogenase. Nonventilation during total cardiopulmonary bypass compared with ventilation resulted in lower pulmonary venous P(O2) values (57+/-15 torr [7.6+/-2.0 kPa] vs. 103+/-23 torr [13.7+/-3.1 kPa]) and higher thromboxane B2 concentrations (488+/-95 pg/mL vs. 434+/-92 pg/mL). The concentrations of endothelin-1, big-endothelin, lactate, and lactate dehydrogenase in the pulmonary veins did not differ significantly between nonventilated and ventilated lungs. CONCLUSIONS Development of pulmonary tissue hypoxia during 1 hr of nonventilation and cardiopulmonary bypass with completely inhibited pulmonary arterial blood flow is unlikely, suggesting that enough oxygen is stored in or is provided to the collapsed lung. Thus, nonventilation during total cardiopulmonary bypass does not appear to contribute to postoperative respiratory dysfunction by causing pulmonary tissue hypoxia. These results, however, do not exclude that mechanical factors of ventilation might benefit the lung during cardiopulmonary bypass.
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Affiliation(s)
- S A Loer
- Department of Anesthesiology, Heinrich-Heine-University, Düsseldorf, Germany
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Sato K, Morio Y, Morris KG, Rodman DM, McMurtry IF. Mechanism of hypoxic pulmonary vasoconstriction involves ET(A) receptor-mediated inhibition of K(ATP) channel. Am J Physiol Lung Cell Mol Physiol 2000; 278:L434-42. [PMID: 10710514 DOI: 10.1152/ajplung.2000.278.3.l434] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is controversy on the role of endothelin (ET)-1 in the mechanism of hypoxic pulmonary vasoconstriction (HPV). Although HPV is inhibited by ET-1 subtype A (ET(A))-receptor antagonists in animals, it has been reported that ET(A)-receptor blockade does not affect HPV in isolated lungs. Thus we reassessed the role of ET-1 in HPV in both rats and isolated blood- and physiological salt solution (PSS)-perfused rat lungs. In rats, the ET(A)-receptor antagonist BQ-123 and the nonselective ET(A)- and ET(B)-receptor antagonist PD-145065, but not the ET(B)-receptor antagonist BQ-788, inhibited HPV. Similarly, BQ-123, but not BQ-788, attenuated HPV in blood-perfused lungs. In PSS-perfused lungs, either BQ-123, BQ-788, or the combination of both attenuated HPV equally. Inhibition of HPV by combined BQ-123 and BQ-788 in PSS-perfused lungs was prevented by costimulation with angiotensin II. The ATP-sensitive K(+) (K(ATP))-channel blocker glibenclamide also prevented inhibition of HPV by BQ-123 in both lungs and rats. These results suggest that ET-1 contributes to HPV in both isolated lungs and intact animals through ET(A) receptor-mediated suppression of K(ATP)-channel activity.
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Affiliation(s)
- K Sato
- Cardiovascular Pulmonary Research Laboratory, Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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Pearl JM, Wellmann SA, McNamara JL, Lombardi JP, Wagner CJ, Raake JL, Nelson DP. Bosentan prevents hypoxia-reoxygenation-induced pulmonary hypertension and improves pulmonary function. Ann Thorac Surg 1999; 68:1714-21; discussion 1721-2. [PMID: 10585047 DOI: 10.1016/s0003-4975(99)00988-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Acute hypoxia results in increased pulmonary vascular resistance. Despite reoxygenation, pulmonary vascular resistance remains elevated and pulmonary function is altered. Endothelin-1 might contribute to hypoxia-reoxygenation-induced pulmonary hypertension and to reoxygenation injury by stimulating leukocytes. This study was carried out using an established model of hypoxia and reoxygenation to determine whether endothelin-1 blockade with Bosentan could prevent hypoxia-reoxygenation-induced pulmonary hypertension and reoxygenation injury. METHODS Twenty neonatal piglets underwent 90 minutes of hypoxia, 60 minutes of reoxygenation on cardiopulmonary bypass, and 2 hours of recovery. Control animals (n = 12) received no drug treatment, whereas the treatment group (n = 8) received the endothelin-1 receptor antagonist, Bosentan, throughout hypoxia. RESULTS In controls, pulmonary vascular resistance increased during hypoxia to 491% of baseline and remained elevated after reoxygenation; however in the Bosentan group, it increased to only 160% of baseline by end-hypoxia, then decreased to 76% at end-recovery. Arterial endothelin-1 levels in controls increased to 591% of baseline after reoxygenation. Arterial nitrite levels decreased during hypoxia in controls but were maintained in the Bosentan group. Consequently, animals in the Bosentan group had better postreoxygenation pulmonary vascular resistance, A-a gradient, and airway resistance along with lower myeloperoxidase levels than controls. CONCLUSIONS Acute hypoxia and postreoxygenation pulmonary hypertension was attenuated by Bosentan, which maintained nitric oxide levels during hypoxia, decreased leukocyte-mediated injury, and improved pulmonary function.
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Affiliation(s)
- J M Pearl
- Division of Pediatric Cardiothoracic Surgery, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
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Medbø S, Tølløfsrud PA, Saugstad OD. Pulmonary hemodynamics in newborn piglets during hypoxemia and reoxygenation: blocking of the endothelin-1 receptors. Pediatr Res 1999; 46:514-22. [PMID: 10541312 DOI: 10.1203/00006450-199911000-00005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The effects of blocking endothelin (ET) receptors in pulmonary circulation during hypoxemia and reoxygenation were studied in five groups of piglets. Ten minutes before hypoxemia, the Hyp group (n = 10) was given saline and the 1-mg (n = 9) and 5-mg group (n = 9), respectively, were given 1 and 5 mg/kg i.v. SB 217242 (an ET receptor antagonist). Two groups served as normoxic controls. The piglets were ventilated with 8% O2 until base excess was <-20 mmol/L or mean arterial blood pressure was <20 mm Hg. Reoxygenation was performed with air. The increase of mean pulmonary artery pressure was significantly attenuated during hypoxemia and reoxygenation in the 1-mg group (p = 0.006). The pulmonary vascular resistance index increased significantly at the end of hypoxemia in the Hyp and 5-mg groups but was comparable to baseline in the 1-mg group. During the study period, the changes in pulmonary vascular resistance index were significantly attenuated in the 1-mg group compared with the 5-mg group. Stroke volume index was significantly attenuated compared with baseline in the 5-mg group during both hypoxemia and reoxygenation, whereas, in the Hyp and 1-mg group, stroke volume index was attenuated only at the end of hypoxemia. During hypoxemia, plasma ET-1 decreased from 1.9+/-0.2 to 1.3+/-0.3 ng/L (p = 0.008) in the Hyp group, remained unchanged in the 1-mg group, and increased from 1.6+/-0.2 to 6.6+/-1.6 ng/L (p = 0.008) in the 5-mg group. We conclude that blocking ET receptors attenuates pulmonary vasoconstriction during hypoxemia and reoxygenation in piglets.
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Affiliation(s)
- S Medbø
- Department of Pediatric Research, Institute for Surgical Research, The National Hospital, Oslo, Norway
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Abstract
Hypoxic vasoconstriction is unique to pulmonary circulation. The pulmonary response is part of a self-regulatory mechanism by which pulmonary capillary blood flow is automatically adjusted to alveolar ventilation for maintaining the optimal balance of ventilation and perfusion. In pathological conditions, hypoxic pulmonary vasoconstriction may occur as an acute episode or as a sustained response with pulmonary hypertension and vascular remodeling. Vasoactive substances produced from the endothelial cells (prostanoids, nitric oxide, or endothelin) or other mediators such as 5 hydroxytryptamine have been examined as possible mediators of hypoxic vasoconstriction. These appear more likely to be modulators than mediators of the vasoconstrictor response to hypoxia. Recent hypotheses have emerged indicating that O2 levels per se can regulate ion channel activity. The modulation of both K+ and Ca2+ channels differs according to the conduit or resistance pulmonary vessel type, tending to extend the former and contract the latter, thereby opposing the ventilation to perfusion mismatching. In the absence of drugs that act selectively on pulmonary circulation, inhaled therapy is an alternative in the treatment of pulmonary hypertension. According to its short half-life and to its potential cytotoxicity, nitric oxide is only of value in the management of patients with acute respiratory disease. Aerosolized prostacyclin and iloprost result in a sustained efficacy of the inhaled vasodilator regimen in patients with severe pulmonary hypertension and offer a new strategy for treatment of this disease. At the moment, therapy aimed at reversing the structural remodeling and matrix deposition in pulmonary arteries remains experimental. New drugs such as potassium channel openers or endothelin receptor antagonists warrant further investigations as possible therapeutic candidates in the treatment of pulmonary hypertension.
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Affiliation(s)
- J P Dumas
- Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaires Expérimentales, Faculté de Médecine, Dijon, France
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Macdonald PD, Paton RD, Logan RW, Skeoch CH, Davis CF. Endothelin-1 levels in infants with pulmonary hypertension receiving extracorporeal membrane oxygenation. J Perinat Med 1999; 27:216-20. [PMID: 10503184 DOI: 10.1515/jpm.1999.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We studied the possibility of an etiological role for endothelin-1 (ET-1) in the development of persistent pulmonary hypertension of the newborn (PPHN). Ten infants with severe PPHN requiring extracorporeal membrane oxygenation (ECMO) were studied. Pre and post pulmonary blood samples were obtained on commencing ECMO and on recovery. The samples were analyzed by radio-immunoassay. The infants with PPHN requiring ECMO had a significantly higher mean ET-1 concentration (21.1 pmol/l, S. D. 3.59) than a group of healthy controls (16.6 pmol/l, S. D. 4.44); however 8 of our 10 infants had individual ET-1 levels within our reference range for healthy newborns. Pre and post pulmonary ET-1 levels did not differ significantly and there was no evidence of a decline in ET-1 levels with resolution of PPHN. Pulmonary overproduction of ET-1 does not appear to be the cause of PPHN, although the endothelin system may still play a role in the pathophysiology of PPHN, probably mediated through changes in receptor expression.
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Affiliation(s)
- P D Macdonald
- Department of Neonatal Pediatrics, Royal Hospital for Sick Children, Yorkhill, Glasgow, U.K
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48
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Pape D, Goineau S, Guillo P, Durand-Castel X, Bellissant E. Endothelin, but not angiotensin II, contributes to the hypoxic contractile response of large isolated pulmonary arteries in the rat. Fundam Clin Pharmacol 1999; 13:461-7. [PMID: 10456287 DOI: 10.1111/j.1472-8206.1999.tb00004.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
UNLABELLED The aims of this study were to investigate whether angiotensin II and/or endothelin could contribute to the hypoxic contractile response of isolated rat pulmonary artery. Experiments were performed for 1 h on noradrenaline precontracted arterial rings in hypoxic conditions (95% N2 and 5% CO2). Nicardipine, lisinopril, losartan, phosphoramidon, FR139317 and bosentan were used to block Ca2+ channels, angiotensin I-converting enzyme, AT1 receptors, endothelin-converting enzyme, ETA receptors, and ETA/ETB receptors, respectively. The profile of the hypoxic contractile response was biphasic, displaying, after a short relaxation, a weak and transient contraction (from 2-4 min) and then, before complete relaxation, a slowly developed but sustained contraction (from 14-60 min). Endothelium removal abolished the transient contraction and reduced (-59%) the sustained contraction. Nicardipine did not modify the transient contraction, but concentration-dependently decreased (from -35% to -100%) the sustained contraction (P = 0.024). Lisinopril and losartan did not affect the response (P = 0.418 and P = 0.973, respectively). Bosentan did not modify the transient contraction, but concentration-dependently decreased (from -14% to -71%) the sustained contraction (P = 0.016), whereas phosphoramidon and FR139317 did not affect the response (P = 0.830 and P = 0.806, respectively). CONCLUSIONS In rat, (i) both phases of the hypoxic contractile response are endothelium-dependent and independent of angiotensin II; (ii) the transient contraction does not depend on endothelin; (iii) the sustained contraction, which involves calcium influx, appears partly dependent on mature endothelin released from storage granules by stimulating ETB receptors.
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Affiliation(s)
- D Pape
- Laboratoire de Pharmacologie Expérimentale et Clinique, UPRES EA 1263 Electrophysiologie et Hémodynamique de l'Insuffisance Cardiaque Faculté de Médecine, Rennès, France
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Franco-Cereceda A, Holm P, Brodin LA, Liska J, Larsen FF. ET-1 infusion increases systemic vascular resistance and depresses cardiac output in patients with chronic hypoxaemia and pulmonary hypertension. Scand Cardiovasc J Suppl 1999; 33:151-6. [PMID: 10399802 DOI: 10.1080/14017439950141777] [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: 10/17/2022]
Abstract
The pulmonary vascular effects of the endothelium-derived peptide endothelin (ET) vary depending on the existing vascular tone, modes of administration and species studied; ET can cause both pulmonary vasodilatation and vasoconstriction. Increased plasma levels of ET have been reported in hypoxic pulmonary hypertension, although it is unclear whether ET is a mediator or a marker of hypoxia-induced increase in pulmonary vascular resistance (PVR). In our study, the plasma levels of ET-1 and the functional effects of ET-1 infusion in patients (n = 4) with chronic hypoxaemia and elevated PVR were evaluated. At rest, the arterial and venous ET-1-levels (13 +/- 2 and 12 +/- 1 fmol/ml, respectively) were significantly higher than those detected in venous plasma of an age-matched healthy control group (7 +/- 1 fmol/ml). Consecutive 10 min infusions of ET-1 at 1, 5, 10 and 15 ng/kg/min into the pulmonary artery decreased cardiac output (by 32%) and stroke volume (by 33%) and increased the systemic vascular resistance (by 62%) and arteriovenous oxygen difference (by 83%) at the highest dose. No deleterious effect was observed in the pulmonary circulation. The present study therefore suggests that intra-pulmonarily administered ET does not attenuate the increased PVR associated with chronic hypoxaemia.
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Affiliation(s)
- A Franco-Cereceda
- Department of Thoracic Surgery, Karolinska Hospital, Stockholm, Sweden.
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Jones RD, Wanstall JC, Gambino A, Morice AH. The effect of the endothelin ET(A) receptor antagonist CI-1020 on hypoxic pulmonary vasoconstriction. Eur J Pharmacol 1999; 374:367-75. [PMID: 10422781 DOI: 10.1016/s0014-2999(99)00300-3] [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: 01/23/2023]
Abstract
The mechanism of Hypoxic Pulmonary Vasoconstriction is unknown. The role of endothelin-1 in hypoxic pulmonary vasoconstriction was studied in precontracted small and large pulmonary arteries using the endothelin ETA receptor antagonist sodium-2-benzol [1,3]dioxol-5-yl-4-(4-methoxyphenyl)-4-oxo-3-(3,4,5-trimethoxy-ben zyl)-but-2-enoate (CI-1020). Small rat pulmonary arteries exhibit a mixed endothelin ETA receptor and endothelin ETB2 receptor population whereas large rat pulmonary arteries contain only endothelin ETA receptors. CI-1020 inhibited endothelin-1 in small vessels via endothelin ETA receptor blockade (1 and 10 microM) and at high concentrations via endothelin ETA receptor and endothelin ETB2 receptor blockade (100 microM). CI-1020 (0.01, 0.1 and 1 microM) inhibited endothelin-1 in large vessels via endothelin ETA receptor blockade alone. CI-1020 (1, 10 and 100 microM) significantly reduced hypoxic pulmonary vasoconstriction in small vessels, by -9.8+/-1.4, -9.2+/-2.3 and -8.0+/-1.7% 80 mM K+, respectively, compared to +2.5+/-4.2% with vehicle (P < 0.05). CI-1020 (0.01, 0.1 and 1 microM) had no significant effect upon hypoxic pulmonary vasoconstriction in large vessels. In small, but not large, pulmonary arteries hypoxic pulmonary vasoconstriction is due in part to the action of endothelin-1 at the endothelin ETA receptor.
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Affiliation(s)
- R D Jones
- Department of Medicine, The University of Hull, Castle Hill Hospital, Yorkshire, UK
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