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Fermoyle CC, Stewart GM, Borlaug BA, Johnson BD. Effects of exercise on thoracic blood volumes, lung fluid accumulation, and pulmonary diffusing capacity in heart failure with preserved ejection fraction. Am J Physiol Regul Integr Comp Physiol 2020; 319:R602-R609. [PMID: 32936678 DOI: 10.1152/ajpregu.00192.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Patients with heart failure with preserved ejection fraction (HFpEF) experience symptoms of exertional dyspnea that may be related to lung fluid accumulation during exercise. A computed tomography (CT)-based method was used to measure exercise-induced changes in extravascular lung fluid content and thoracic blood volumes and to determine the effect of lung fluid on lung diffusing capacity for carbon monoxide (DLCO) in stable subjects with HFpEF and healthy controls. Nine subjects with HFpEF (age = 68 ± 8 yr; body mass index = 32.1 ± 2.6 kg/m2) and eight healthy controls (62 ± 9 yr, 23.8 ± 2.4 kg/m2) performed triplicate rebreathe DLCO/DLNO (lung diffusing capacity for nitric oxide) tests in a supine position at rest and duplicate measurements during two 5-min submaximal exercise stages (15W and 35W) and recovery. Subjects subsequently performed a 5-min exercise bout (35W) inside a CT scanner, and extravascular lung fluid content and thoracic blood volumes were quantified at rest and immediately following exercise from thoracic and contrast perfusion scans, respectively. Subjects with HFpEF had a higher lung fluid content at rest compared with controls (means ± SD, HFpEF: 14.4 ± 1.7%, control: 12.8 ± 1.7%, P = 0.043) and a higher lung fluid content following exercise (15.2 ± 2.0% vs. 12.6 ± 1.5%, P = 0.009). Higher lung fluid content was associated with a lower DLCO and alveolar-capillary membrane conductance (Dm) in subjects with HFpEF (DLCO: R = -0.57, P = 0.022, Dm: R = -0.61, P = 0.012) but not in controls. Pulmonary blood volume was not altered by exercise and was similar between groups. Submaximal exercise elicited a greater accumulation of lung fluid in subjects with HFpEF compared with in controls, and lung fluid content was negatively correlated with lung diffusing capacity and alveolar-capillary membrane conductance in subjects with HFpEF.
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Affiliation(s)
- Caitlin C Fermoyle
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, Minnesota
| | - Glenn M Stewart
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Barry A Borlaug
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Bruce D Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
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2
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Fang XY, Chen Z, Miao GB, Zhang L. Expression of β1- and β2-adrenergic receptors in the lungs and changes in the levels of corresponding autoantibodies in an aged rat model of heart failure. Int J Mol Med 2016; 38:1933-1939. [PMID: 27779651 DOI: 10.3892/ijmm.2016.2786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 10/11/2016] [Indexed: 11/06/2022] Open
Abstract
β-adrenergic receptors (β-ARs) and anti-β1-AR autoantibodies play important roles in heart failure. This study was designed to investigate the expression of β1- and β2-ARs in the lungs, and their relevance to the corresponding autoantibodies in an aged rat model of heart failure. In addition, we investigated the association between anti-β-AR autoantibody and soluble Fas (sFas) and soluble Fas ligand (sFasL). Aged male Wistar rats were divided into the sham-operated control group and the heart failure group. At 0 and 9 weeks post-surgery, the protein levels of β1- and β2-ARs in the heart and lungs were measured by western blot analysis. The plasma concentrations of autoantibodies, sFas and sFasL were determined by enzyme-linked immunosorbent assay (ELISA). The protein levels of pulmonary β1- and β2-ARs were decreased in the heart failure group when compared with the control group (P<0.01). Both the frequencies of the occurrence and the titers of autoantibodies against β2-AR increased at 9 weeks post-surgery (P<0.01). The levels of sFas and sFasL were also elevated, although there was no difference in the levels of sFas and sFasL between the groups, with positive and negative anti-β-AR autoantibody. These findings suggested that during the development of heart failure, the densities of pulmonary β1- and β2-ARs decreased. The levels of anti-β2-AR autoantibody exhibited similar changes as those of anti-β1-AR autoantibody, and there was no definite association between anti-β-AR autoantibody and the levels of sFas/sFasL.
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Affiliation(s)
- Xiang-Yang Fang
- Department of Internal Medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Zhe Chen
- Department of Internal Medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Guo-Bin Miao
- Heart Center, Beijing Tsinghua Changgung Hospital, Beijing 102218, P.R. China
| | - Lin Zhang
- Heart Center, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, P.R. China
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Taylor BJ, Snyder EM, Richert ML, Wheatley CM, Chase SC, Olson LJ, Johnson BD. Effect of β 2-adrenergic receptor stimulation on lung fluid in stable heart failure patients. J Heart Lung Transplant 2016; 36:418-426. [PMID: 27863863 DOI: 10.1016/j.healun.2016.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 08/05/2016] [Accepted: 09/21/2016] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND The purpose of this study was to determine: (1) whether stable heart failure patients with reduced ejection fraction (HFrEF) have elevated extravascular lung water (EVLW) when compared with healthy control subjects; and (2) the effect of acute β2-adrenergic receptor (β2AR) agonist inhalation on lung fluid balance. METHODS Twenty-two stable HFrEF patients and 18 age- and gender-matched healthy subjects were studied. Lung diffusing capacity for carbon monoxide (DLCO), alveolar-capillary membrane conductance (DmCO), pulmonary capillary blood volume (Vc) (via re-breathe) and lung tissue volume (Vtis) (via computed tomography) were assessed before and within 30 minutes after administration of nebulized albuterol. EVLW was derived as Vtis - Vc. RESULTS Before administration of albuterol, Vtis and EVLW were higher in HFrEF vs control (998 ± 200 vs 884 ± 123 ml, p = 0.041; and 943 ± 202 vs 802 ± 133 ml, p = 0.015, respectively). Albuterol decreased Vtis and EVLW in HFrEF patients (-4.6 ± 7.8%, p = 0.010; -4.6 ± 8.8%, p = 0.018) and control subjects (-2.8 ± 4.9%, p = 0.029; -3.0 ± 5.7%, p = 0.045). There was an inverse relationship between pre-albuterol values and pre- to post-albuterol change for EVLW (r2 = -0.264, p = 0.015) and DmCO (r2 = -0.343, p = 0.004) in HFrEF only. CONCLUSION Lung fluid is elevated in stable HFrEF patients relative to healthy subjects. Stimulation of β2ARs may cause fluid removal in HFrEF, especially in patients with greater evidence of increased lung water at baseline.
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Affiliation(s)
- Bryan J Taylor
- Faculty of Biological Sciences, School of Biomedical Sciences, University of Leeds, Leeds, UK; Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
| | - Eric M Snyder
- School of Kinesiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Maile L Richert
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Courtney M Wheatley
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Steven C Chase
- Division of Cardiovascular Diseases, Mayo Graduate School, Mayo Clinic, Rochester, Minnesota, USA
| | - Lyle J Olson
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Bruce D Johnson
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA
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Rinaldi B, Capuano A, Gritti G, Donniacuo M, Scotto Di Vettimo A, Sodano L, Rafaniello C, Rossi F, Matera MG. Effects of chronic administration of β-blockers on airway responsiveness in a murine model of heart failure. Pulm Pharmacol Ther 2014; 28:109-13. [PMID: 24769100 DOI: 10.1016/j.pupt.2014.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/29/2014] [Accepted: 04/11/2014] [Indexed: 12/21/2022]
Abstract
Lung function abnormalities, both at rest and during exercise, are frequently observed in patients with chronic heart failure (HF), also in absence of respiratory disease. It has been documented that, in HF, chronic adrenergic stimulation down-regulates β-adrenoceptors (β-ARs) and modifies airway relaxant responses. This study was designed to investigate in an animal model of HF whether a treatment with a β-AR blocker, metoprolol, could modify the altered airway hyperresponsiveness. In rats, randomly assigned to 3 experimental groups sham-operated rats (SH), rats with HF induced by left anterior descending coronaric occlusion (HF n = 10), and rats treated with metoprolol 100 mg/kg/die (MET = 10), HF was evaluated after 10 weeks and resulted in increases in plasma norepinephrine and epinephrine and left ventricular end diastolic pressure. β2-ARs and G-protein-βAR2-kinase (GRK2) mRNA levels were determined by real time reverse transcriptase PCR. Carbachol-precontracted isolated tracheal rings were used to functionally assess airway smooth muscle relaxation. In pulmonary tissues, β2-AR mRNA level was significantly decreased in HF groups (-48.73 ± 5.18%, P < 0.01); in the same groups the GRK2 mRNA-levels were significantly enhanced (+222.50 ± 6.13%, P < 0.001); in lung deriving from MET groups the levels of mRNA were significantly increased (+339.86 ± 11.26%, P < 0.001), while the GRK2 mRNA-levels unchanged (-59.02 ± 3.97%, P < 0.001), when compared to SH groups. Relaxation of tracheal strips in response to salbutamol was significantly reduced in HF groups; in tracheal rings, deriving from MET groups, the relaxant effects of salbutamol were significantly enhanced (SH, Emax: 34.87 ± 2.98%, pD2: 7.45 ± 0.27; HF, Emax: 34.87 ± 2.98%, pD2: 7.45 ± 0.27; MET, Emax: 85.43 ± 6.80%, pD2: 6.95 ± 0.59, P < 0.001). In HF, the down-regulation of pulmonary β-ARs results in a significant attenuation of airway relaxation. These effects have been reversed by a treatment with metoprolol, suggesting a potential role of β-AR blockers in the treatment of patients suffering from HF and chronic obstructive airway diseases.
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Affiliation(s)
- B Rinaldi
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - A Capuano
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - G Gritti
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - M Donniacuo
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - A Scotto Di Vettimo
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - L Sodano
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - C Rafaniello
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - F Rossi
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy; Regional Centre for Pharmacovigilance and Pharmacoepidemiology, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy
| | - M G Matera
- Centre of Excellence for Cardiovascular Diseases, Dept. of Experimental Medicine, Section of Pharmacology "L. Donatelli", Second University of Naples, Italy.
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Tanabe T, Rozycki HJ, Kanoh S, Rubin BK. Cardiac asthma: new insights into an old disease. Expert Rev Respir Med 2013; 6:705-14. [PMID: 23234454 DOI: 10.1586/ers.12.67] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiac asthma has been defined as wheezing, coughing and orthopnea due to congestive heart failure. The clinical distinction between bronchial asthma and cardiac asthma can be straight forward, except in patients with chronic lung disease coexisting with left heart disease. Pulmonary edema and pulmonary vascular congestion have been thought to be the primary causes of cardiac asthma but most patients have a poor response to diuretics. There appears to be limited effectiveness of classical asthma medications like bronchodilators or corticosteroids in treating cardiac asthma. Evidence suggests that circulating inflammatory factors and tissue growth factors also lead to airway obstruction suggesting the possibility of developing novel therapies.
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Affiliation(s)
- Tsuyoshi Tanabe
- Department of Pediatrics, Virginia Commonwealth University School of Medicine and the Children's Hospital of Richmond at VCU, Richmond, VA, USA
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Alkhalil M, Schulman ES, Getsy J. Obstructive sleep apnea syndrome and asthma: the role of continuous positive airway pressure treatment. Ann Allergy Asthma Immunol 2008; 101:350-7. [PMID: 18939721 DOI: 10.1016/s1081-1206(10)60309-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To review the concept of a possible link between asthma and obstructive sleep apnea syndrome (OSAS) and the impact on asthma symptoms of treatment of OSAS with continuous positive airway pressure (CPAP) in patients with both conditions. DATA SOURCES The Ovid, MEDLINE, and PubMed databases from 1950 to the present were searched for relevant articles regarding a possible relationship between asthma and OSAS and the effectiveness of CPAP in treating OSAS. STUDY SELECTION Articles describing pathophysiologic conditions occurring in OSAS that may be linked to asthma pathogenesis were used for this review. RESULTS The data suggest that OSAS is an independent risk factor for asthma exacerbations. CPAP has been shown in prospective clinical studies to have a positive impact on asthma outcome in patients with concomitant OSAS. Ameliorative mechanisms of treatment with CPAP include mechanical and neuromechanical effects, gastroesophageal acid reflux suppression, local and systemic anti-inflammatory effects (including suppression of increased serum levels of inflammatory cytokines, chemokines, and vascular endothelial growth factor), cardiac function improvements, leptin level suppression, weight reduction, and sleep restoration. CONCLUSIONS Asthma and OSAS are increasingly troublesome public health issues. Mounting evidence implicates OSAS as a risk factor for asthma exacerbations, thereby linking these 2 major epidemics. We describe potential mechanisms whereby CPAP, the first line of therapy for OSAS, might modify airway smooth muscle function and asthma control in patients with both disorders. Despite the ever-increasing population of patients with both disorders, large, prospective, randomized controlled studies are necessary to more fully evaluate CPAP and asthma outcomes.
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Affiliation(s)
- Michel Alkhalil
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA.
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7
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Buss SJ, Backs J, Kreusser MM, Hardt SE, Maser-Gluth C, Katus HA, Haass M. Spironolactone preserves cardiac norepinephrine reuptake in salt-sensitive Dahl rats. Endocrinology 2006; 147:2526-34. [PMID: 16439456 DOI: 10.1210/en.2005-1167] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An impairment of cardiac norepinephrine (NE) reuptake via the neuronal NE transporter (NET) enhances the effects of increased cardiac NE release in heart failure patients. Increasing evidence suggests that aldosterone and endothelins promote sympathetic overstimulation of failing hearts. Salt-sensitive Dahl rats (DS) fed a high-salt diet developed arterial hypertension and diastolic heart failure as well as elevated plasma levels of endothelin-1 and NE. Cardiac NE reuptake and NET-binding sites, as assessed by clearance of bolus-injected [(3)H]NE in isolated perfused rat hearts and [(3)H]mazindol binding, were reduced. Treatment of DS with the mineralocorticoid receptor antagonist spironolactone preserved the plasma levels of endothelin-1 and NE, cardiac NE reuptake, and myocardial NET density. Moreover, the ventricular function and survival of spironolactone-treated DS were significantly improved compared with untreated DS. The alpha(1)-inhibitor prazosin decreased blood pressure in DS similar to spironolactone treatment, but did not normalize the plasma levels of endothelin-1 and NE, NE reuptake, or ventricular function. In a heart failure-independent model, Wistar rats that were infused with aldosterone and fed a high-salt diet developed impaired cardiac NE reuptake. Treatment of these rats with the endothelin A receptor antagonist darusentan attenuated the impairment of NE reuptake. In conclusion, spironolactone preserves NET-dependent cardiac NE reuptake in salt-dependent heart failure. Evidence is provided that aldosterone inhibits NET function through an interaction with the endothelin system. Selective antagonism of the mineralocorticoid and/or the endothelin A receptor might represent therapeutic principles to prevent cardiac sympathetic overactivity in salt-dependent heart failure.
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Affiliation(s)
- Sebastian J Buss
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, 75390-9148, USA
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8
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Andreas S, Anker SD, Scanlon PD, Somers VK. Neurohumoral activation as a link to systemic manifestations of chronic lung disease. Chest 2005; 128:3618-24. [PMID: 16304321 DOI: 10.1378/chest.128.5.3618] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
COPD is a major cause of death and disability worldwide. Treatment of COPD improves lung function but is unlikely to slow the steady downhill course of the disease or reduce mortality. In COPD, numerous abnormalities can be found outside the lung. These include systemic inflammation, cachexia, and skeletal muscle dysfunction. Thus, COPD has been called a systemic disease. Convincing data demonstrate that COPD causes neurohumoral activation. By precedents derived from chronic heart failure and other diseases characterized by neurohumoral activation, we propose that the negative consequences of neurohumoral activation, namely inflammation, cachexia, effects on ventilation, and skeletal muscle dysfunction, give rise to a self-perpetuating cycle that contributes to the pathogenesis of COPD, and which may involve respiratory muscle dysfunction as well as systemic inflammation. This concept may further help explain the increased cardiovascular morbidity and mortality in COPD patients. Currently, little is known about the effect of treatments directed at neurohumoral activation and COPD. As this aspect of COPD becomes better understood, new insights may direct novel therapeutic approaches.
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Affiliation(s)
- Stefan Andreas
- Department of Cardiology and Pneumology, Georg-August-University, Göttingen, Germany.
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Matsumoto T, Wakabayashi K, Kobayashi T, Kamata K. Functional changes in adenylyl cyclases and associated decreases in relaxation responses in mesenteric arteries from diabetic rats. Am J Physiol Heart Circ Physiol 2005; 289:H2234-43. [PMID: 15894571 DOI: 10.1152/ajpheart.00971.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To assess the functional change in adenylyl cyclases (AC) associated with the diabetic state, we investigated AC-mediated relaxations and cAMP production in mesenteric arteries from rats with streptozotocin (STZ)-induced diabetes. The relaxations induced by the water-soluble forskolin (FSK) analog NKH477, which is a putative AC5 activator, but not by the beta-adrenoceptor agonist isoproterenol (Iso) and the AC activator FSK, were reduced in intact diabetic mesenteric artery. In diabetic rats, however, Iso-, FSK-, and NKH477-induced relaxations were attenuated in the presence of inhibitors of nitric oxide synthase and cyclooxygenase. To exclude the influence of phosphodiesterase (PDE), we also examined the relaxations induced by several AC activators in the presence of 3-isobutyl-1-methylxanthine (IBMX; a PDE inhibitor). Under these conditions, the relaxation induced by Iso was greatly impaired in STZ-diabetic rats. This Iso-induced relaxation was significantly attenuated by pretreatment with SQ-22536, an AC inhibitor, in mesenteric rings from age-matched controls but not in those from STZ-diabetic rats. Under the same conditions, the relaxations induced by FSK or NKH477 were impaired in STZ-diabetic rats. Neither FSK- nor A-23187 (a Ca2+ ionophore)-induced cAMP production was significantly different between diabetics and controls. However, cAMP production induced by Iso or NKH477 was significantly impaired in diabetic mesenteric arteries. Expression of mRNAs and proteins for AC5/6 was lower in diabetic mesenteric arteries than in controls. These results suggest that AC-mediated relaxation is impaired in the STZ-diabetic rat mesenteric artery, perhaps reflecting a reduction in AC5/6 activity.
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Affiliation(s)
- Takayuki Matsumoto
- Dept. of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi Univ., Shinagawa-ku, Tokyo 142-8501, Japan
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Sobolewski A, Jourdan KB, Upton PD, Long L, Morrell NW. Mechanism of cicaprost-induced desensitization in rat pulmonary artery smooth muscle cells involves a PKA-mediated inhibition of adenylyl cyclase. Am J Physiol Lung Cell Mol Physiol 2004; 287:L352-9. [PMID: 15107293 DOI: 10.1152/ajplung.00270.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Long-term infusion of prostacyclin, or its analogs, is an effective treatment for severe pulmonary arterial hypertension. However, dose escalation is often required to maintain efficacy. The aim of this study was to investigate the mechanisms of prostacyclin receptor desensitization using the prostacyclin analog cicaprost in rat pulmonary artery smooth muscle cells (PASMCs). Desensitization of the cAMP response occurred in 63 nM cicaprost after a 6-h preincubation with agonist. This desensitization was reversed 12 h after agonist removal, and resensitization was inhibited by 10 microg/ml of cycloheximide. Desensitization was heterologous since desensitization to other G(s)alpha-adenylyl cyclase (AC)-coupled agonists, isoproterenol (1 microM), adrenomedullin (100 nM), or bradykinin (1 microM), was also reduced by preincubation with cicaprost. The reduced cAMP response to prolonged cicaprost exposure appeared to be due to inhibition of AC activity since the responses to the directly acting AC agonist forskolin (3 microM) and the selective AC5 activator NKH-477 were similarly reduced. Expression of AC2 and AC5/6 protein levels transiently decreased after 1 h of cicaprost exposure. The PKA inhibitor H-89 (1 microM) added 1 h before cicaprost preincubation (6 h, 63 nM) completely reversed cicaprost-induced desensitization, whereas the PKC inhibitor bisindolylmaleimide (100 nM) was only partly effective. Desensitization was not prevented by the G(i) inhibitor pertussis toxin. In conclusion, chronic treatment of PASMCs with cicaprost induced heterologous, reversible desensitization by inhibition of AC activity. Our data suggest that heterologous G(s)alpha desensitization by cicaprost is mediated predominantly by a PKA-inhibitable isoform of AC, most likely AC5/6.
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Affiliation(s)
- Anastasia Sobolewski
- Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, United Kingdom
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Meyer MF, Hopkins WE, Kaminsky DA. Cardiovascular collapse in a 77-year-old-woman with an asthma exacerbation following bronchodilator treatment. Chest 2003; 124:1160-3. [PMID: 12970051 DOI: 10.1378/chest.124.3.1160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Markus F Meyer
- Department of Medicine, Fletcher Allen Health Care, University of Vermont College of Medicine, Burlington, VT 05405, USA
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12
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Backs J, Haunstetter A, Gerber SH, Metz J, Borst MM, Strasser RH, Kübler W, Haass M. The neuronal norepinephrine transporter in experimental heart failure: evidence for a posttranscriptional downregulation. J Mol Cell Cardiol 2001; 33:461-72. [PMID: 11181015 DOI: 10.1006/jmcc.2000.1319] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
An impairment of norepinephrine (NE) re-uptake by the neuronal NE transporter (NET) has been shown to contribute to the increased cardiac net-release of NE in congestive heart failure (CHF). The present study investigated which mechanisms are involved in the impairment of NET. Rats with supracoronary aortic banding characterized by myocardial hypertrophy, elevated left ventricular end diastolic pressures and severe pulmonary congestion were used as an experimental model for CHF. Compared to sham-operated controls, aortic-banded rats had enhanced plasma NE concentrations and decreased cardiac NE stores. In isolated perfused hearts of aortic-banded rats, functional impairment of NET was indicated by a 37% reduction in [(3)H]-NE-uptake. In addition, pharmacological blockade of NET with desipramine led to a markedly attenuated increase in the overflow of endogenous NE from hearts of aortic-banded rats. Determination of cardiac NET protein and of NET mRNA in the left stellate ganglion by [(3)H]-desipramine binding and competitive RT-PCR, respectively, revealed a 41% reduction of binding sites but no difference in gene expression. The density of sympathetic nerve fibers within the heart was unchanged, as shown by glyoxylic acid-induced histofluorescence. In conclusion, as impairment of intracardiac NE re-uptake by a reduction of NET binding sites is neither mediated by a decreased NET gene expression nor by a loss of noradrenergic nerve terminals, a posttranscriptional downregulation of NET per neuron is suggested in CHF.
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Affiliation(s)
- J Backs
- Department of Cardiology, University of Heidelberg, Bergheimer Str. 58, 69115 Heidelberg, Germany
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