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Baloglu E, Nonnenmacher G, Seleninova A, Berg L, Velineni K, Ermis-Kaya E, Mairbäurl H. The role of hypoxia-induced modulation of alveolar epithelial Na +- transport in hypoxemia at high altitude. Pulm Circ 2020; 10:50-58. [PMID: 33110497 PMCID: PMC7557693 DOI: 10.1177/2045894020936662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/02/2020] [Indexed: 12/14/2022] Open
Abstract
Reabsorption of excess alveolar fluid is driven by vectorial Na+-transport across alveolar epithelium, which protects from alveolar flooding and facilitates gas exchange. Hypoxia inhibits Na+-reabsorption in cultured cells and in-vivo by decreasing activity of epithelial Na+-channels (ENaC), which impairs alveolar fluid clearance. Inhibition also occurs during in-vivo hypoxia in humans and laboratory animals. Signaling mechanisms that inhibit alveolar reabsorption are poorly understood. Because cellular adaptation to hypoxia is regulated by hypoxia-inducible transcription factors (HIF), we tested whether HIFs are involved in decreasing Na+-transport in hypoxic alveolar epithelium. Expression of HIFs was suppressed in cultured rat primary alveolar epithelial cells (AEC) with shRNAs. Hypoxia (1.5% O2, 24 h) decreased amiloride-sensitive transepithelial Na+-transport, decreased the mRNA expression of α-, β-, and γ-ENaC subunits, and reduced the amount of αβγ-ENaC subunits in the apical plasma membrane. Silencing HIF-2α partially prevented impaired fluid reabsorption in hypoxic rats and prevented the hypoxia-induced decrease in α- but not the βγ-subunits of ENaC protein expression resulting in a less active form of ENaC in hypoxic AEC. Inhibition of alveolar reabsorption also caused pulmonary vasoconstriction in ventilated rats. These results indicate that a HIF-2α-dependent decrease in Na+-transport in hypoxic alveolar epithelium decreases alveolar reabsorption. Because susceptibles to high-altitude pulmonary edema (HAPE) have decreased Na+-transport even in normoxia, inhibition of alveolar reabsorption by hypoxia at high altitude might further impair alveolar gas exchange. Thus, aggravated hypoxemia might further enhance hypoxic pulmonary vasoconstriction and might subsequently cause HAPE.
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Affiliation(s)
- Emel Baloglu
- Department of Pharmacology, Acibadem Mehmet Ali Aydinlar University, School of Medicine, Istanbul, Turkey.,Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany
| | | | - Anna Seleninova
- Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany
| | - Lena Berg
- Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany
| | - Kalpana Velineni
- Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany
| | - Ezgi Ermis-Kaya
- Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany
| | - Heimo Mairbäurl
- Translational Lung Research Center Heidelberg (TLRC), Heidelberg, Germany.,Translational Pneumology, University Hospital Heidelberg, Heidelberg, Germany
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Involvement of the Bufadienolides in the Detection and Therapy of the Acute Respiratory Distress Syndrome. Lung 2017; 195:323-332. [PMID: 28260175 DOI: 10.1007/s00408-017-9989-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/20/2017] [Indexed: 12/12/2022]
Abstract
PURPOSE The acute respiratory distress syndrome (ARDS) represents a major challenge for clinicians as well as basic scientists. The mortality rate for ARDS has been maintained within the range of 40-52%. The authors have examined the involvement of the "cardiotonic steroids" in the pathogenesis and therapy of ARDS. We have studied the possible role of the bufadienolide, marinobufagenin (MBG), in the pathogenesis of ARDS in both a rat model of ARDS and in patients afflicted with that disorder. In addition, the potential therapeutic benefit of an antagonist of MBG, resibufogenin (RBG), in an animal model has been evaluated. METHOD A syndrome resembling human ARDS was produced in the rat by exposing the animals to 100% oxygen for 48 h. In other animals, RBG was administered to these "hyperoxic" rats, and the serum MBG was measured. In human ICU patients, urinary samples were examined for levels of MBG, and the values were compared to those obtained from other ICU patients admitted with diagnoses other than ARDS. RESULTS (1) Exposure of rats to hyperoxia produced a histologic picture which resembled that of human ARDS. (2) Serum levels of MBG in the "hyperoxic" rats substantially exceeded those obtained in animals exposed to ambient oxygen levels and were reduced to normal by RBG. (3) In ARDS patients, substantial elevations in urinary MBG were obtained compared to those in non-ARDS ICU patients. CONCLUSIONS MBG may serve as an important biomarker for the development of ARDS, and RBG may represent a preventative/therapy in this disorder.
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Li J, Huang S, Wu Y, Gu C, Gao D, Feng C, Wu X, Fu X. Paracrine factors from mesenchymal stem cells: a proposed therapeutic tool for acute lung injury and acute respiratory distress syndrome. Int Wound J 2013; 11:114-21. [PMID: 24373614 DOI: 10.1111/iwj.12202] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 10/24/2013] [Accepted: 11/20/2013] [Indexed: 12/22/2022] Open
Abstract
Despite extensive researches in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), current pharmacological therapies and respiratory support are still the main methods to treat patients with ALI and ARDS and the effects remain limited. Hence, innovative therapies are needed to decrease the morbidity and mortality. Because of the proven therapeutic effects in other fields, mesenchymal stem cells (MSCs) might be considered as a promising alternative to treat ALI and ARDS. Numerous documents demonstrate that MSCs can exert multiple functions, such as engraftment, differentiation and immunoregulation, but now the key researches are concentrated on paracrine factors secreted by MSCs that can mediate endothelial and epithelial permeability, increase alveolar fluid clearance and other potential mechanisms. This review aimed to review the current researches in terms of the effects of MSCs on ALI and ARDS and to analyse these paracrine factors, as well as to predict the potential directions and challenges of the application in this field.
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Affiliation(s)
- Jiwei Li
- Department of Thoracic and Cardiovascular Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, P. R. China; Key Laboratory of Wound Repair and Regeneration of PLA, The First Affiliated Hospital, General Hospital of PLA, Trauma Center of Postgraduate Medical College, Beijing, P. R. China
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Ion transport by pulmonary epithelia. J Biomed Biotechnol 2011; 2011:174306. [PMID: 22131798 PMCID: PMC3205707 DOI: 10.1155/2011/174306] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 08/16/2011] [Indexed: 12/13/2022] Open
Abstract
The lung surface of air-breathing vertebrates is formed by a continuous epithelium that is covered by a fluid layer. In the airways, this epithelium is largely pseudostratified consisting of diverse cell types such as ciliated cells, goblet cells, and undifferentiated basal cells, whereas the alveolar epithelium consists of alveolar type I and alveolar type II cells. Regulation and maintenance of the volume and viscosity of the fluid layer covering the epithelium is one of the most important functions of the epithelial barrier that forms the outer surface area of the lungs. Therefore, the epithelial cells are equipped with a wide variety of ion transport proteins, among which Na+, Cl−, and K+ channels have been identified to play a role in the regulation of the fluid layer. Malfunctions of pulmonary epithelial ion transport processes and, thus, impairment of the liquid balance in our lungs is associated with severe diseases, such as cystic fibrosis and pulmonary oedema. Due to the important role of pulmonary epithelial ion transport processes for proper lung function, the present paper summarizes the recent findings about composition, function, and ion transport properties of the airway epithelium as well as of the alveolar epithelium.
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Matalon S, Eaton DC. Dale J. Benos, Ph.D. (1950-2010). Am J Physiol Lung Cell Mol Physiol 2011; 300:L509-11. [PMID: 21296896 DOI: 10.1152/ajplung.00022.2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Chamorro-Marín V, García-Delgado M, Touma-Fernández A, Aguilar-Alonso E, Fernández-Mondejar E. Intratracheal dopamine attenuates pulmonary edema and improves survival after ventilator-induced lung injury in rats. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 12:R39. [PMID: 18331631 PMCID: PMC2447566 DOI: 10.1186/cc6829] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 11/14/2007] [Accepted: 03/10/2008] [Indexed: 11/15/2022]
Abstract
Intoduction Clearance of alveolar oedema depends on active transport of sodium across the alveolar-epithelial barrier. β-Adrenergic agonists increase clearance of pulmonary oedema, but it has not been established whether β-agonist stimulation achieves sufficient oedema clearance to improve survival in animals. The objective of this study was to determine whether the increased pulmonary oedema clearance produced by intratracheal dopamine improves the survival of rats after mechanical ventilation with high tidal volume (HVT). Methods This was a randomized, controlled, experimental study. One hundred and thirty-two Wistar-Kyoto rats, weighing 250 to 300 g, were anaesthetized and cannulated via endotracheal tube. Pulmonary oedema was induced by endotracheal instillation of saline solution and mechanical ventilation with HVT. Two types of experiment were carried out. The first was an analysis of pulmonary oedema conducted in six groups of 10 rats ventilated with low (8 ml/kg) or high (25 ml/kg) tidal volume for 30 or 60 minutes with or without intratracheally instilled dopamine. At the end of the experiment the animals were exsanguinated and pulmonary oedema analysis performed. The second experiment was a survival analysis, which was conducted in two groups of 36 animals ventilated with HVT for 60 minutes with or without intratracheal dopamine; survival of the animals was monitored for up to 7 days after extubation. Results In animals ventilated at HVT with or without intratracheal dopamine, oxygen saturation deteriorated over time and was significantly higher at 30 minutes than at 60 minutes. After 60 minutes, a lower wet weight/dry weight ratio was observed in rats ventilated with HVT and instilled with dopamine than in rats ventilated with HVT without dopamine (3.9 ± 0.27 versus 4.9 ± 0.29; P = 0.014). Survival was significantly (P = 0.013) higher in animals receiving intratracheal dopamine and ventilated with HVT, especially at 15 minutes after extubation, when 11 of the 36 animals in the HVT group had died as compared with only one out of the 36 animals in the HVT plus dopamine group. Conclusion Intratracheal dopamine instillation increased pulmonary oedema clearance in rats ventilated with HVT, and this greater clearance was associated with improved survival.
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Affiliation(s)
- Virginia Chamorro-Marín
- Unidad Experimental, Hospital Universitario Virgen de las Nieves, C/Dr, Azpitarte n4, 18014, Granada, Spain.
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Saumon G. Introduction to alveolar liquid clearance during lung injury: a crucial function – long ignored. Intensive Care Med 2007; 33:1241-1242. [PMID: 17530223 DOI: 10.1007/s00134-007-0625-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Georges Saumon
- INSERM U773, Centre de Recherche Bichat Beaujon CRB3, BP 416, 75018, Paris, France.
- Université Paris 7 Denis Diderot, site Bichat, BP 416, 75018, Paris, France.
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Abstract
One of the biggest challenges a newborn faces after birth is the task of making a smooth transition to air breathing. This task is complicated by the fact that fetal lungs are full of fluid which must be cleared rapidly to allow for gas exchange. Respiratory morbidity as a result of failure to clear fetal lung fluid is not uncommon, and can be particularly problematic in some infants delivered by elective cesarean delivery (ECS). Given the high rates of cesarean deliveries in the USA and worldwide, the public health and economic impact of morbidity in this subgroup is considerable. Whereas the occurrence of birth asphyxia, trauma, and meconium aspiration is reduced by elective Cesarean delivery, the risk of respiratory distress secondary to transient tachypnea of the newborn, surfactant deficiency, and pulmonary hypertension is increased. It is clear that physiologic events in the last few weeks of pregnancy coupled with the onset of spontaneous labor are accompanied by changes in the hormonal milieu of the fetus and its mother, resulting in preparation of the fetus for neonatal transition. Rapid clearance of fetal lung fluid is a key part of these changes, and is mediated in large part by transepithelial Na reabsorption through amiloride-sensitive Na channels in the alveolar epithelial cells, with only a limited contribution from mechanical factors and Starling forces. This chapter discusses the physiologic mechanisms underlying fetal lung fluid absorption and explores potential strategies for facilitating neonatal transition when infants are delivered by ECS before the onset of spontaneous labor.
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Affiliation(s)
- Lucky Jain
- Emory University School of Medicine, Atlanta, GA 30322, USA.
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Abstract
Respiratory morbidity in near term (> or =34 and <37 weeks) infants delivered spontaneously or by elective cesarean section (ECS) has been well documented in the literature, and accounts for a significant number of admissions to intensive care units among these neonates. Given the high rates of near-term deliveries in the USA and worldwide, the public health and economic impact of morbidity in this subgroup is considerable. Causes of respiratory distress include transient tachypnea of the newborn (TTNB), surfactant deficiency, pneumonia, and pulmonary hypertension. There is considerable evidence that physiologic events in the last few weeks of pregnancy coupled with the onset of spontaneous labor are accompanied by changes in the hormonal milieu of the fetus and its mother, resulting in rapid maturation and preparation of the fetus for delivery and neonatal transition. A surge in endogenous steroids and catecholamines accompanies term gestation and spontaneous vaginal delivery, and is responsible for some of the maturational effects. Rapid clearance of fetal lung fluid clearance plays a key role in the transition to air breathing. The bulk of this fluid clearance is mediated by transepithelial sodium reabsorption through amiloride-sensitive sodium channels in the alveolar epithelial cells with only a limited contribution from mechanical factors and Starling forces. Disruption of this process can lead to retention of fluid in air spaces, setting the stage for alveolar hypoventilation. When infants are delivered near-term, especially by cesarean section (repeat or primary) before the onset of spontaneous labor, the fetus is often deprived of these hormonal changes, making the neonatal transition more difficult. This chapter discusses the physiologic mechanisms underlying fetal lung fluid absorption and explores potential strategies for facilitating neonatal transition.
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Affiliation(s)
- Lucky Jain
- Emory University School of Medicine, Atlanta, GA 30322, USA
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Abstract
The mechanisms of pulmonary edema resolution are different from those regulating edema formation. Absorption of excess alveolar fluid is an active process that involves vectorial transport of Na+out of alveolar air spaces with water following the Na+osmotic gradient. Active Na+transport across the alveolar epithelium is regulated via apical Na+and chloride channels and basolateral Na-K-ATPase in normal and injured lungs. During lung injury, mechanisms regulating alveolar fluid reabsorption are inhibited by yet unclear pathways and can be upregulated by pharmacological means. Better understanding of the mechanisms that regulate edema clearance may lead to therapeutic interventions to improve the ability of lungs to clear fluid, which is of clinical significance.
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Affiliation(s)
- Gökhan M Mutlu
- Pulmonary and Critical Care Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
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Le Berre R, Faure K, Fauvel H, Viget NB, Ader F, Prangère T, Thomas AM, Leroy X, Pittet JF, Marchetti P, Guery BP. Apoptosis inhibition in P. aeruginosa-induced lung injury influences lung fluid balance. Intensive Care Med 2004; 30:1204-11. [PMID: 14991100 DOI: 10.1007/s00134-004-2165-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Accepted: 12/30/2003] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Pseudomonas aeruginosa-induced lung injury is characterized not only by the alteration in lung fluid movement but also by apoptosis of lung epithelial and endothelial cells. We studied whether inhibition of apoptosis using a broad spectrum caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone (Z-VAD.fmk), would affect lung fluid balance in rat P. aeruginosa pneumonia. METHODS Z-VAD.fmk (3 mg/kg) was administered intravenously simultaneously with P. aeruginosa intratracheal instillation (0.5 ml/kg, 2 x 10(9) CFU/ml). Apoptosis was evaluated with the TUNEL technique, cytoplasmic oligonucleosome assay, and caspase 3 activation. To evaluate lung permeability, extravascular plasma equivalent (EPE) and lung wet to dry weight ratio (W/D) were measured 4 h after intratracheal instillation of P. aeruginosa. RESULTS We found an increase of lung apoptosis 4 h after P. aeruginosa instillation: cytoplasmic oligonucleosome assay increased from 3.17+/-0.78 to 26.82+/-4.67 ODx1000/mg of proteins/ml, Z-VAD.fmk administration decreased this parameter to 10.3+/-2.98 ODx1000/mg of proteins/ml. Caspase 3 levels followed the same pattern. Apoptosis involved both epithelial cells and endothelial cells. Endothelial permeability was increased after Pseudomonas instillation: W/D increased from 3.75+/-0.28 in the Co group to 4.42+/-0.23 in the Pn group; EPE was also higher in the Pn group compared with the Co group (0.125+/-0.04 and 0.002+/-0.01 ml, respectively). Both of these parameters were improved after Z-VAD.fmk administration; W/D decreased to 3.36+/-0.25 and EPE to 0.02+/-0.02 ml. CONCLUSION Apoptosis occurs in the early phase of P. aeruginosa pneumonia. Administration of Z-VAD.fmk significantly decreases DNA fragmentation and caspase 3 levels. This is associated with an improvement of endothelial permeability and lung fluid balance.
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Affiliation(s)
- Rozenn Le Berre
- Laboratoire de Recherche en Pathologie Infectieuse, 2689 Lille, France
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Tillie-Leblond I, Guery BPH, Janin A, Leberre R, Just N, Pittet JF, Tonnel AB, Gosset P. Chronic bronchial allergic inflammation increases alveolar liquid clearance by TNF-alpha -dependent mechanism. Am J Physiol Lung Cell Mol Physiol 2002; 283:L1303-9. [PMID: 12388371 DOI: 10.1152/ajplung.00147.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Bronchial inflammation in allergic asthma is associated with active exudation from the bronchial tree into the interstitial space of both mucosa and submucosa. The aim of this study was to evaluate epithelial and endothelial permeability as well as alveolar fluid movement in a model of chronic allergic inflammation in Brown-Norway rats sensitized and challenged with ovalbumin (OA). Control groups were challenged with saline solution (C), and rats were immunized by OA but not challenged (Se). Lung sections showed a marked inflammatory infiltrate associated with perivascular and peribronchiolar edema in OA. To measure alveolar liquid clearance, a 5% bovine albumin solution with 1 microCi of (125)I-labeled human albumin was instilled into the air spaces. Alveolar-capillary barrier permeability was evaluated by intravascular injection of 1 microCi of (131)I-labeled albumin. Endothelial permeability was significantly increased in OA, from 0.08 +/- 0.01 in the C group to 0.19 +/- 0.03 in OA group (P < 0.05). Final-to-initial protein ratio was also statistically higher in OA (1.6 +/- 0.05) compared with C (1.38 +/- 0.03, P = 0.01) and Se groups (1.42 +/- 0.03, P = 0.04). Administration of anti-tumor necrosis factor-alpha antibodies within the instillate significantly decreased this ratio (1.32 +/- 0.08, P = 0.003 vs. OA). To conclude, we demonstrated a tumor necrosis factor-alpha-dependent increase in alveolar fluid movement in a model of severe bronchial allergic inflammation associated with endothelial and epithelial leakage.
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Affiliation(s)
- Isabelle Tillie-Leblond
- Institut National de la Santé et de la Recherche Médicale U416, Institut Pasteur de Lille, 59019 Lille, France
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Abstract
Early studies of fluid transport across the pulmonary epithelium were conducted in intact animals or isolated lungs. Although the location and cells responsible for transport cannot be determined with studies in whole mammalian lungs, such preparations remain indispensable for determining the physiological and clinical relevance of in vitro investigations of cells and their transport proteins. Three different approaches have been used to study transport and exchange between the vascular and air space compartments in intact lungs. Some of the advantages and limitations of these methods are briefly reviewed here.
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Affiliation(s)
- Edward D Crandall
- Will Rogers Institute Pulmonary Research Center, University of Southern California, Los Angeles, California 90033, USA.
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Sakagami M, Byron PR, Rypacek F. Biochemical evidence for transcytotic absorption of polyaspartamide from the rat lung: effects of temperature and metabolic inhibitors. J Pharm Sci 2002; 91:1958-68. [PMID: 12210043 DOI: 10.1002/jps.10188] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Airway-to-perfusate polyhydroxyethylaspartamide (PHEA) absorption was studied in the isolated perfused rat lung at a reduced temperature and by the use of metabolic inhibitors, to kinetically clarify the mechanisms and cellular pathways of its active absorption. Fluorophore-labeled PHEA (F-PHEA; 7.4 kDa) was administered into the airways, and its absorption followed with time at 25 degrees C and in the presence of 2,4-dinitrophenol (DNP), ouabain (OUA), monensin (MON), and nocodazole (NOC). Across-dose absorption profiles were analyzed using a kinetic model incorporating active (V(max,P) and K(m,P)) and passive (k(a,P)) absorption from the pulmonary lung region alongside the competing, pulmonary-to-bronchial mucociliary escalator (k(E)). The model was validated at 25 degrees C and a lack of perturbation on the k(a,P) and k(E) values for passively absorbed solutes confirmed by studying the disposition of sodium fluorescein and 4.4 kDa fluorescein isothiocyanate-labeled dextran. F-PHEA absorption was significantly suppressed at 25 degrees C, compared with 37 degrees C, because of a significant decrease in the value of the maximum rate of active absorption, V(max,P) (4.37 --> 0.67 microg/min; p < 0.05), whereas the carrier-affinity term, K(m,P), was statistically unchanged. F-PHEA's active absorption was also significantly inhibited by DNP (> or =0.5 mM), OUA (> or =50 microM), MON (> or =10 microM), and NOC (> or =1 microM), whereas these inhibitors had no significant effect on the values for k(a,P) and k(E). Thus, F-PHEA's pulmonary active absorption in the rat lung was temperature- and adenosine 5'-triphosphate-derived intracellular energy-dependent (DNP and OUA inhibition) and apparently mediated via transcytosis through cytoplasmic endosomes and microtubules (MON and NOC inhibition).
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Affiliation(s)
- Masahiro Sakagami
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, P. O. Box 980533, Richmond, Virginia 23298, USA
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Wang E, Simard M, Ouellet N, Bergeron Y, Beauchamp D, Bergeron MG. Pathogenesis of pneumococcal pneumonia in cyclophosphamide-induced leukopenia in mice. Infect Immun 2002; 70:4226-38. [PMID: 12117931 PMCID: PMC128150 DOI: 10.1128/iai.70.8.4226-4238.2002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae pneumonia frequently occurs in leukopenic hosts, and most patients subsequently develop lung injury and septicemia. However, few correlations have been made so far between microbial growth, inflammation, and histopathology of pneumonia in specific leukopenic states. In the present study, the pathogenesis of pneumococcal pneumonia was investigated in mice rendered leukopenic by the immunosuppressor antineoplastic drug cyclophosphamide. Compared to the immunocompetent state, cyclophosphamide-induced leukopenia did not hamper interleukin-1 (IL-1), IL-6, macrophage inflammatory protein-1 (MIP-1), MIP-2, and monocyte chemotactic protein-1 secretion in infected lungs. Leukopenia did not facilitate bacterial dissemination into the bloodstream despite enhanced bacterial proliferation into lung tissues. Pulmonary capillary permeability and edema as well as lung injury were enhanced in leukopenic mice despite the absence of neutrophilic and monocytic infiltration into their lungs, suggesting an important role for bacterial virulence factors and making obvious the fact that neutrophils are ultimately not required for lung injury in this model. Scanning and transmission electron microscopy revealed extensive disruption of alveolar epithelium and a defect in surfactant production, which were associated with alveolar collapse, hemorrhage, and fibrin deposits in alveoli. These results contrast with those observed in immunocompetent animals and indicate that leukopenic hosts suffering from pneumococcal pneumonia are at a higher risk of developing diffuse alveolar damage.
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Affiliation(s)
- Erjian Wang
- Infectious Diseases Research Center, Laval University, Quebec City, Canada G1V 4G2
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Matthay MA, Folkesson HG, Clerici C. Lung epithelial fluid transport and the resolution of pulmonary edema. Physiol Rev 2002; 82:569-600. [PMID: 12087129 DOI: 10.1152/physrev.00003.2002] [Citation(s) in RCA: 490] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The discovery of mechanisms that regulate salt and water transport by the alveolar and distal airway epithelium of the lung has generated new insights into the regulation of lung fluid balance under both normal and pathological conditions. There is convincing evidence that active sodium and chloride transporters are expressed in the distal lung epithelium and are responsible for the ability of the lung to remove alveolar fluid at the time of birth as well as in the mature lung when pathological conditions lead to the development of pulmonary edema. Currently, the best described molecular transporters are the epithelial sodium channel, the cystic fibrosis transmembrane conductance regulator, Na+-K+-ATPase, and several aquaporin water channels. Both catecholamine-dependent and -independent mechanisms can upregulate isosmolar fluid transport across the distal lung epithelium. Experimental and clinical studies have made it possible to examine the role of these transporters in the resolution of pulmonary edema.
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Affiliation(s)
- Michael A Matthay
- Cardiovascular Research Institute and Department of Medicine, University of California, San Francisco, California 94143-0624, USA.
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Ghofrani HA, Kohstall MG, Weissmann N, Schmehl T, Schermuly RT, Seeger W, Grimminger F. Alveolar epithelial barrier functions in ventilated perfused rabbit lungs. Am J Physiol Lung Cell Mol Physiol 2001; 280:L896-904. [PMID: 11290513 DOI: 10.1152/ajplung.2001.280.5.l896] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We employed ultrasonic nebulization for homogeneous alveolar tracer deposition into ventilated perfused rabbit lungs. (22)Na and (125)I-albumin transit kinetics were monitored on-line with gamma detectors placed around the lung and the perfusate reservoir. [(3)H]mannitol was measured by repetitive counting of perfusion fluid samples. Volume of the alveolar epithelial lining fluid was estimated with bronchoalveolar lavage with sodium-free isosmolar mannitol solutions. Sodium clearance rate was -2.2 +/- 0.3%/min. This rate was significantly reduced by preadministration of ouabain/amiloride and enhanced by pretreatment with aerosolized terbutaline. The (125)I-albumin clearance rate was -0.40 +/- 0.05%/min. The appearance of [(3)H]mannitol in the perfusate was not influenced by ouabain/amiloride or terbutaline but was markedly enhanced by pretreatment with aerosolized protamine. An epithelial lining fluid volume of 1.22 +/- 0.21 ml was calculated in control lungs. Fluid absorption rate was 1.23 microl x g lung weight(-1) x min(-1), which was blunted after pretreatment with ouabain/amiloride. We conclude that alveolar tracer loading by aerosolization is a feasible technique to assess alveolar epithelial barrier properties in aerated lungs. Data on active and passive sodium flux, paracellular solute transit, and net fluid absorption correspond well to those in previous studies in fluid-filled lungs; however, albumin clearance rates were markedly higher in the currently investigated aerated lungs.
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Affiliation(s)
- H A Ghofrani
- Department of Internal Medicine, Justus-Liebig-University Giessen, 35385 Giessen, Germany
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Viget NB, Guery BP, Ader F, Nevière R, Alfandari S, Creuzy C, Roussel-Delvallez M, Foucher C, Mason CM, Beaucaire G, Pittet JF. Keratinocyte growth factor protects against Pseudomonas aeruginosa-induced lung injury. Am J Physiol Lung Cell Mol Physiol 2000; 279:L1199-209. [PMID: 11076810 DOI: 10.1152/ajplung.2000.279.6.l1199] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously reported that keratinocyte growth factor (KGF) attenuates alpha-naphthylthiourea-induced lung injury by upregulating alveolar fluid transport. The objective of this study was to determine the effect of KGF pretreatment in Pseudomonas aeruginosa pneumonia. A 5% bovine albumin solution with 1 microCi of (125)I-labeled human albumin was instilled into the air spaces 4 or 24 h after intratracheal instillation of P. aeruginosa, and the concentration of unlabeled and labeled proteins in the distal air spaces over 1 h was used as an index of net alveolar fluid clearance. Alveolocapillary barrier permeability was evaluated with an intravascular injection of 1 microCi of (131)I-albumin. In early pneumonia, KGF increased lung liquid clearance (LLC) compared with that in nonpretreated animals. In late pneumonia, LLC was significantly reduced in the absence of KGF but increased above the control value with KGF. KGF pretreatment increased the number of polymorphonuclear cells recovered in the bronchoalveolar lavage fluid and decreased bacterial pulmonary translocation. In conclusion, KGF restores normal alveolar epithelial fluid transport during the acute phase of P. aeruginosa pneumonia and LLC in early and late pneumonia. Host response is also improved as shown by the increase in the alveolar cellular response and the decrease in pulmonary translocation of bacteria.
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Affiliation(s)
- N B Viget
- Laboratoire de Recherche en Pathologie Infectieuse, EA 2689, 59045 Lille, France
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19
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Factor P, Dumasius V, Saldias F, Brown LA, Sznajder JI. Adenovirus-mediated transfer of an Na+/K+-ATPase beta1 subunit gene improves alveolar fluid clearance and survival in hyperoxic rats. Hum Gene Ther 2000; 11:2231-42. [PMID: 11084680 DOI: 10.1089/104303400750035753] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Pulmonary edema is cleared via active Na(+) transport by alveolar epithelial Na(+)/K(+)-ATPases and Na(+) channels. Rats exposed to acute hyperoxia have a high mortality rate, decreased Na(+)/K(+)-ATPase function, and decreased alveolar fluid clearance (AFC). We hypothesized that Na(+)/K(+)-ATPase subunit gene overexpression could improve AFC in rats exposed to hyperoxia. We delivered 4 x 10(9) PFU of recombinant adenoviruses containing rat alpha(1) and beta(1) Na(+)/K(+)-ATPase subunit cDNAs (adalpha(1) and adbeta(1), respectively) to rat lungs 7 days prior to exposure to 100% O(2) for 64 hr. As compared with controls and ad alpha(1), AFC in the adbeta(1) rats was increased by >300%. Permeability for large solutes was less in the ad beta(1) than in the other hyperoxia groups. Glutathione oxidation, but not superoxide dismutase activity, was increased only in the adbeta(1) group. Survival through 14 days of hyperoxia was 100% in the adbeta(1) group but was not different from hyperoxic controls in animals given adalpha(1). Our data show that overexpression of a beta(1) Na(+)/K(+)-ATPase subunit augments AFC and improves survival in this model of acute lung injury via antioxidant-independent mechanisms. Conceivably, restoration of AFC via gene transfer of Na(+)/K(+)-ATPase subunit genes may prove useful for the treatment of acute lung injury and pulmonary edema.
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Affiliation(s)
- P Factor
- Pulmonary and Critical Care Medicine, Evanston Northwestern Healthcare, Evanston, IL 60201, USA.
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20
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Frank JA, Wang Y, Osorio O, Matthay MA. Beta-adrenergic agonist therapy accelerates the resolution of hydrostatic pulmonary edema in sheep and rats. J Appl Physiol (1985) 2000; 89:1255-65. [PMID: 11007557 DOI: 10.1152/jappl.2000.89.4.1255] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether beta-adrenergic agonist therapy increases alveolar liquid clearance during the resolution phase of hydrostatic pulmonary edema, we studied alveolar and lung liquid clearance in two animal models of hydrostatic pulmonary edema. Hydrostatic pulmonary edema was induced in sheep by acutely elevating left atrial pressure to 25 cmH(2)O and instilling 6 ml/kg body wt isotonic 5% albumin (prepared from bovine albumin) in normal saline into the distal air spaces of each lung. After 1 h, sheep were treated with a nebulized beta-agonist (salmeterol) or nebulized saline (controls), and left atrial pressure was then returned to normal. beta-Agonist therapy resulted in a 60% increase in alveolar liquid clearance over 3 h (P < 0.001). Because the rate of alveolar fluid clearance in rats is closer to human rates, we studied beta-agonist therapy in rats, with hydrostatic pulmonary edema induced by volume overload (40% body wt infusion of Ringer lactate). beta-Agonist therapy resulted in a significant decrease in excess lung water (P < 0.01) and significant improvement in arterial blood gases by 2 h (P < 0.03). These preclinical experimental studies support the need for controlled clinical trials to determine whether beta-adrenergic agonist therapy would be of value in accelerating the resolution of hydrostatic pulmonary edema in patients.
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Affiliation(s)
- J A Frank
- Departments of Medicine and Anesthesia, Cardiovascular Research Institute, University of California, San Francisco, California 94143-0130, USA
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21
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Olivera WG, Ciccolella DE, Barquin N, Ridge KM, Rutschman DH, Yeates DB, Sznajder JI. Aldosterone regulates Na,K-ATPase and increases lung edema clearance in rats. Am J Respir Crit Care Med 2000; 161:567-73. [PMID: 10673201 DOI: 10.1164/ajrccm.161.2.9808050] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Aldosterone increases the Na,K-ATPase function in renal cells involved in active Na(+) transport. Because the alveolar type 2 (AT2) cells participate in active Na(+) transport, we studied whether aldosterone regulates the Na,K-ATPase in rat AT2 cells and whether aldosterone delivered by aerosols to spontaneously breathing rats affects edema clearance in a model of isolated-perfused lungs. The AT2 cells treated with aldosterone had increased Na,K-ATPase beta1-subunit mRNA and protein, which was associated with a 4-fold increase in the Na,K-ATPase hydrolytic activity and the ouabain-sensitive (86)Rb(+) uptake. In physiologic experiments, 24 h after aldosterone was delivered by aerosols to the rat air spaces, the active Na(+) transport and lung edema clearance increased by approximately 53% as compared with control rats and rats in which saline aerosols were delivered. The data suggest that increased active Na(+) transport and lung edema clearance induced by aldosterone is probably due to Na,K-ATPase regulation in alveolar epithelial cells. Conceivably, aldosterone may be used as a strategy to increase lung edema clearance.
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Affiliation(s)
- W G Olivera
- Pulmonary and Critical Care Medicine Division, Northwestern University Medical School, Chicago, IL 60611, USA
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22
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DeCoursey TE. Hypothesis: do voltage-gated H(+) channels in alveolar epithelial cells contribute to CO(2) elimination by the lung? Am J Physiol Cell Physiol 2000; 278:C1-C10. [PMID: 10644504 DOI: 10.1152/ajpcell.2000.278.1.c1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although alveolar epithelial cells were the first mammalian cells in which voltage-gated H(+) currents were recorded, no specific function has yet been proposed. Here we consider whether H(+) channels contribute to one of the main functions of the lung: CO(2) elimination. This idea builds on several observations: 1) some cell membranes have low CO(2) permeability, 2) carbonic anhydrase is present in alveolar epithelium and contributes to CO(2) extrusion by facilitating diffusion, 3) the transepithelial potential difference favors selective activation of H(+) channels in apical membranes, and 4) the properties of H(+) channels are ideally suited to the proposed role. H(+) channels open only when the electrochemical gradient for H(+) is outward, imparting directionality to the diffusion process. Unlike previous facilitated diffusion models, HCO(-)(3) and H(+) recombine to form CO(2) in the alveolar subphase. Rough quantitative considerations indicate that the proposed mechanism is plausible and indicate a significant capacity for CO(2) elimination by the lung by this route. Fully activated alveolar H(+) channels extrude acid equivalents at three times the resting rate of CO(2) production.
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Affiliation(s)
- T E DeCoursey
- Department of Molecular Biophysics and Physiology, Rush Presbyterian St. Luke's Medical Center, Chicago, Illinois 60612, USA.
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23
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Verghese GM, Ware LB, Matthay BA, Matthay MA. Alveolar epithelial fluid transport and the resolution of clinically severe hydrostatic pulmonary edema. J Appl Physiol (1985) 1999; 87:1301-12. [PMID: 10517756 DOI: 10.1152/jappl.1999.87.4.1301] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To characterize the rate and regulation of alveolar fluid clearance in the uninjured human lung, pulmonary edema fluid and plasma were sampled within the first 4 h after tracheal intubation in 65 mechanically ventilated patients with severe hydrostatic pulmonary edema. Alveolar fluid clearance was calculated from the change in pulmonary edema fluid protein concentration over time. Overall, 75% of patients had intact alveolar fluid clearance (>/=3%/h). Maximal alveolar fluid clearance (>/=14%/h) was present in 38% of patients, with a mean rate of 25 +/- 12%/h. Hemodynamic factors (including pulmonary arterial wedge pressure and left ventricular ejection fraction) and plasma epinephrine levels did not correlate with impaired or intact alveolar fluid clearance. Impaired alveolar fluid clearance was associated with a lower arterial pH and a higher Simplified Acute Physiology Score II. These factors may be markers of systemic hypoperfusion, which has been reported to impair alveolar fluid clearance by oxidant-mediated mechanisms. Finally, intact alveolar fluid clearance was associated with a greater improvement in oxygenation at 24 h along with a trend toward shorter duration of mechanical ventilation and an 18% lower hospital mortality. In summary, alveolar fluid clearance in humans may be rapid in the absence of alveolar epithelial injury. Catecholamine-independent factors are important in the regulation of alveolar fluid clearance in patients with severe hydrostatic pulmonary edema.
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Affiliation(s)
- G M Verghese
- Departments of Medicine and Anesthesia and the Cardiovascular Research Institute, University of California, San Francisco, California 94143-0130, USA
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24
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Chalaka S, Ingbar DH, Sharma R, Zhau Z, Wendt CH. Na(+)-K(+)-ATPase gene regulation by glucocorticoids in a fetal lung epithelial cell line. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:L197-203. [PMID: 10409248 DOI: 10.1152/ajplung.1999.277.1.l197] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Na(+) pump, Na(+)-K(+)-ATPase, along with the Na(+) channel is essential for the removal of alveolar solute and fluid perinatally. Because Na(+)-pump mRNA and activity increase before birth and maternal glucocorticoids (GCs) influence Na(+)-K(+)-ATPase mRNA expression in fetal rat lung, we hypothesized that GCs increased Na(+)-K(+)-ATPase gene expression in a fetal lung epithelial cell line. After 24 h of exposure, dexamethasone increased the steady-state levels of Na(+)-K(+)-ATPase alpha(1) and beta(1) mRNA in a fetal rat lung epithelial cell line in a dose-dependent fashion (10(-7) to 10(-5) M). The maximal increase in mRNA levels was 3. 8-fold for alpha(1) and 2.8-fold for beta(1). The increase in mRNA was detected as early as 6 h for the beta(1)-subunit and 18 h for the alpha(1)-subunit, and both peaked at 24 h. This gene upregulation was not due to increased mRNA stability based on mRNA half-life determination after actinomycin D inhibition. Transfection experiments with alpha(1) and beta(1) promoter-reporter constructs demonstrated 3.2 +/- 0.5- and 2.6 +/- 0.4-fold increases, respectively, in promoter activity, consistent with transcriptional activation of the promoter-reporter construct. These findings, increased promoter activity with no change in stability, indicate that GCs increased Na(+)-K(+)-ATPase transcription in a fetal lung epithelial cell line.
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Affiliation(s)
- S Chalaka
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455, USA
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25
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Matalon S, O'Brodovich H. Sodium channels in alveolar epithelial cells: molecular characterization, biophysical properties, and physiological significance. Annu Rev Physiol 1999; 61:627-61. [PMID: 10099704 DOI: 10.1146/annurev.physiol.61.1.627] [Citation(s) in RCA: 295] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
At birth, fetal distal lung epithelial (FDLE) cells switch from active chloride secretion to active sodium (Na+) reabsorption. Sodium ions enter the FDLE and alveolar type II (ATII) cells mainly through apical nonselective cation and Na(+)-selective channels, with conductances of 4-26 pS (picoSiemens) in FDLE and 20-25 pS in ATII cells. All these channels are inhibited by amiloride with a 50% inhibitory concentration of < 1 microM, and some are also inhibited by [N-ethyl-N-isopropyl]-2'-4'-amiloride (50% inhibitory concentration of < 1 microM). Both FDLE and ATII cells contain the alpha-, beta-, and gamma-rENaC (rat epithelial Na+ channels) mRNAs; reconstitution of an ATII cell Na(+)-channel protein into lipid bilayers revealed the presence of 25-pS Na+ single channels, inhibited by amiloride and [N-ethyl-N-isopropyl]-2'-4'-amiloride. A variety of agents, including cAMP, oxygen, glucocorticoids, and in some cases Ca2+, increased the activity and/or rENaC mRNA levels. The phenotypic properties of these channels differ from those observed in other Na(+)-absorbing epithelia. Pharmacological blockade of alveolar Na+ transport in vivo, as well as experiments with newborn alpha-rENaC knock-out mice, demonstrate the importance of active Na+ transport in the reabsorption of fluid from the fetal lung and in reabsorbing alveolar fluid in the injured adult lung. Indeed, in a number of inflammatory diseases, increased production of reactive oxygen-nitrogen intermediates, such as peroxynitrite (ONOO-), may damage ATII and FDLE Na+ channels, decrease Na+ reabsorption in vivo, and thus contribute to the formation of alveolar edema.
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Affiliation(s)
- S Matalon
- Department of Anesthesiology, University of Alabama at Birmingham 35233, USA.
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26
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Abstract
Role of CFTR in Airway Disease. Physiol. Rev. 79, Suppl.: S215-S255, 1999. - Cystic fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR), which accounts for the cAMP-regulated chloride conductance of airway epithelial cells. Lung disease is the chief cause of morbidity and mortality in CF patients. This review focuses on mechanisms whereby the deletion or impairment of CFTR chloride channel function produces lung disease. It examines the major themes of the channel hypothesis of CF, which involve impaired regulation of airway surface fluid volume or composition. Available evidence indicates that the effect of CFTR deletion alters physiological functions of both surface and submucosal gland epithelia. At the airway surface, deletion of CFTR causes hyperabsorption of sodium chloride and a reduction in the periciliary salt and water content, which impairs mucociliary clearance. In submucosal glands, loss of CFTR-mediated salt and water secretion compromises the clearance of mucins and a variety of defense substances onto the airway surface. Impaired mucociliary clearance, together with CFTR-related changes in the airway surface microenvironment, leads to a progressive cycle of infection, inflammation, and declining lung function. Here, we provide the details of this pathophysiological cascade in the hope that its understanding will promote the development of new therapies for CF.
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Affiliation(s)
- J M Pilewski
- Departments of Medicine and of Cell Biology and Physiology, University of Pittsburgh, Pennsylvania, USA
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Affiliation(s)
- R J Mason
- Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
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28
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Carter EP, Wangensteen OD, Dunitz J, Ingbar DH. Hyperoxic effects on alveolar sodium resorption and lung Na-K-ATPase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:L1191-202. [PMID: 9435574 DOI: 10.1152/ajplung.1997.273.6.l1191] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Active Na+ transport by the alveolar epithelium keeps alveoli relatively dry. Hyperoxia increases epithelial permeability, resulting in pulmonary edema. We sought to determine whether active Na+ resorption from the air spaces and Na-K-ATPase activity increased in rats exposed to > 95% O2 for 60 h. The permeability x surface area products for unidirectional resorption of alveolar [14C]sucrose (PSsucrose) and 22Na+ (PSNa+) were measured in isolated, perfused rat lungs immediately after hyperoxia and after 3 and 7 days of recovery in room air. At 60 h of hyperoxia, the mean PSsucrose and PSNa+ increased from 6.71 +/- 0.8 x 10(-5) to 12.6 +/- 1.6 x 10(-5) cm3/s (P = 0.029) and from 23.6 +/- 1.1 x 10(-5) to 31.0 +/- 1.6 x 10(-5) cm3/s (P < 0.008), respectively. However, the values in individual rats ranged widely from no change to nearly a fourfold increase. Subgroup analysis revealed that benzamil- or amiloride-sensitive (transcellular) PSNa+ was significantly reduced in the exposed lungs with normal PSsucrose but was maintained in the lungs with high PSsucrose. By day 3 of recovery, mean Na+ and sucrose fluxes returned to values similar to control. Na-K-ATPase membrane hydrolytic maximal velocity (Vmax) activity fell significantly immediately after hyperoxic exposure but recovered to normal values by day 3 of recovery. The Na-K-ATPase beta 1-subunit antigenic signal did not significantly change, whereas the alpha 1-subunit levels increased during recovery. In summary, there was a heterogeneous response of different rats to acute hyperoxia. Hyperoxia led to complex, nonparallel changes in Na+ pump antigenic protein, hydrolytic activity, and unidirectional active Na+ resorption. Active Na+ transport was differentially affected, depending on degree of injury, but permeability and transport normalized by day 3 of recovery.
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Affiliation(s)
- E P Carter
- Department of Physiology, School of Medicine, University of Minnesota, Minneapolis 55455, USA
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29
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Sakuma T, Nishimura T, Usude K, Handa M, Okaniwa G, Suzuki S, Fujimura S. Hypothermia inhibits the alveolar epithelial injury caused by hyposmotic albumin solution during preservation of the resected human lung. Surg Today 1997; 27:527-33. [PMID: 9306546 DOI: 10.1007/bf02385806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study was conducted to determine whether hypothermia inhibited alveolar epithelial injury in the resected human lung during preservation. Hyposmotic albumin solution, 248 mOsm/kg, was instilled into the alveolar spaces of resected human lungs which were inflated with an airway pressure of 7 cmH2O and stored at either 37 degrees C or 8 degrees C for 4 h. Alveolar fluid was aspirated and the influx of lactate dehydrogenase (LDH) and globulin into the alveolar spaces, as markers of alveolar epithelial injury, was measured. Ion transport and fluid clearance across the alveolar epithelium were calculated by the changes in electrolyte and albumin concentrations in the alveolar fluid, respectively. While the LDH levels and globulin concentrations increased significantly in the hyposmotic experiments at 37 degrees C, hypothermia inhibited these increases. Alveolar fluid clearance at 37 degrees C increased to 20% in the hyposmotic experiments compared with 12% in the control isosmotic experiments; however, sodium and chloride transport in the hyposmotic experiments was not significantly different from that in the isosmotic experiments. Thus, we conclude that hypothermia at 8 degrees C inhibits alveolar epithelial injury caused by the hyposmotic solution in resected human lungs. Moreover, alveolar ion and fluid clearance mechanisms were preserved across the injured alveolar epithelial cells.
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Affiliation(s)
- T Sakuma
- Department of Surgery, Sendai Kosei Hospital, Japan
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30
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Mairbäurl H, Wodopia R, Eckes S, Schulz S, Bärtsch P. Impairment of cation transport in A549 cells and rat alveolar epithelial cells by hypoxia. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:L797-806. [PMID: 9357855 DOI: 10.1152/ajplung.1997.273.4.l797] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A reduced cation reabsorption across the alveolar epithelium decreases water reabsorption from the alveoli and could diminish clearing accumulated fluid. To test whether hypoxia restricts cation transport in alveolar epithelial cells, cation uptake was measured in rat lung alveolar type II pneumocytes (AII cells) in primary culture and in A549 cells exposed to normoxia and hypoxia. In AII and A549 cells, hypoxia caused a PO2-dependent inhibition of the Na-K pump, of Na-K-2Cl cotransport, and of total and amiloride-sensitive 22Na uptake. Nifedipine failed to prevent hypoxia-induced transport inhibition in both cell types. In A549 cells, the inhibition of the Na-K pump and Na-K-2Cl cotransport occurred within approximately 30 min of hypoxia, was stable >20 h, and was reversed by 2 h of reoxygenation. There was also a reduction in cell membrane-associated Na-K-ATPase and a decrease in Na-K-2Cl cotransport flux after full activation with calyculin A, indicating a decreased transport capacity. [14C]serine incorporation into cell proteins was reduced in hypoxic A549 cells, but inhibition of protein synthesis with cycloheximide did not reduce ion transport. In AII and A549 cells, ATP levels decreased slightly, and ADP and the ATP-to-ADP ratio were unchanged after 4 h of hypoxia. In A549 cells, lactate, intracellular Na, and intracellular K were unchanged. These results indicate that hypoxia inhibits apical Na entry pathways and the basolateral Na-K pump in A549 cells and rat AII pneumocytes in culture, indicating a hypoxia-induced reduction of transepithelial Na transport and water reabsorption by alveolar epithelium. If similar changes occur in vivo, the impaired cation transport across alveolar epithelial cells might contribute to the formation of hypoxic pulmonary edema.
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Affiliation(s)
- H Mairbäurl
- Department of Sports Medicine, University of Heidelberg, Germany
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31
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Tibayan FA, Chesnutt AN, Folkesson HG, Eandi J, Matthay MA. Dobutamine increases alveolar liquid clearance in ventilated rats by beta-2 receptor stimulation. Am J Respir Crit Care Med 1997; 156:438-44. [PMID: 9279221 DOI: 10.1164/ajrccm.156.2.9609141] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Although it is well known that beta-adrenergic agonist stimulation increases alveolar epithelial sodium and fluid transport, it is not known whether the beta-1 or the beta-2 receptor mediates this effect. Two clinically relevant beta-adrenergic agonists, dopamine (beta-1 agonist) and dobutamine (beta-1 and beta-2 agonist) were used to define the contribution of these two beta-receptors to beta-adrenergic stimulated fluid clearance from the air spaces of the lungs. Alveolar fluid clearance was measured in anesthetized, ventilated rats over one hour after instilling an isosmolar 5% albumin solution in Ringer's lactate with 3 microCi 125I-albumin. The concentrations of the labeled and unlabeled albumin were used to quantify alveolar liquid clearance. Dopamine, whether given intra-alveolar (10(-4) M) or intravenously (5-10 micrograms/kg/min), had no effect. However, both intra-alveolar (10(-4) M) and intravenous (5 micrograms/kg/min) dobutamine increased alveolar liquid clearance by approximately 50% over one hour compared to controls. ICI 118,551, a potent and specific beta-2 antagonist, blocked the effect of dobutamine. The dobutamine effect was blocked by amiloride (10(-3) M), an inhibitor of sodium uptake. In summary, the beta-2 receptor mediates beta-adrenergic stimulation of alveolar epithelial sodium and fluid transport.
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Affiliation(s)
- F A Tibayan
- Cardiovascular Research Institute, University of California, San Francisco 94143-0130, USA
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Mathias NR, Yamashita F, Lee VH. Respiratory epithelial cell culture models for evaluation of ion and drug transport. Adv Drug Deliv Rev 1996. [DOI: 10.1016/s0169-409x(96)00420-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Bundschuh DS, Uhlig S, Leist M, Sauer A, Wendel A. Isolation and characterization of rat primary lung cells. In Vitro Cell Dev Biol Anim 1995; 31:684-91. [PMID: 8564079 DOI: 10.1007/bf02634089] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Lung cell culture may be useful as an in vitro alternative to study the susceptibility of the lung to various toxic agents. Lungs from female Wistar rats were enzymatically digested by recirculating perfusion through the pulmonary artery with a sequence of solutions containing deoxyribonuclease, chymopapain, pronase, collagenase, and elastase. Lung tissue was microdissected and resuspended and the cells obtained were washed by centrifugation. By this isolation method, 2 x 10(8) cells per rat lung were obtained with an average viability of 97%. Lung cells cultured in medium containing antibiotics and serum maintained a viability of > 70% for 5 d. Rat primary lung cells were exposed to various toxic agents and their viability was assessed by formazan production capacity after 18 h of incubation. Compared to rat and mouse hepatocyte cultures (EC50 = 5.8 mM), rat primary lung cells were much more susceptible to hydrogen peroxide (EC50 = 0.6 mM). All cell types were equally sensitive to the more potent toxicant tert-butylhydroperoxide (EC50 = 0.1 mM). Paraquat was more toxic to lung cells (EC50 = 0.03 mM) than to rat (EC50 = 2.8 mM) and mouse (EC50 = 0.2 mM) hepatocytes. In contrast, rat lung cells were less sensitive to sodium nitroprusside (EC50 = 2.6 mM) compared to rat (EC50 = 0.2 mM) and mouse (EC50 = 0.03 mM) hepatocytes. Nitrofurantoin and menadione (at EC50 = 0.04 mM and 0.006 mM, respectively) were more toxic to rat lung and liver cells than to murine hepatocytes (EC50 = 0.2 mM and 0.04 mM, respectively). Our findings demonstrate the applicability of this rat primary lung cell culture for studying the effects of lung toxicants.
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35
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Sakuma T, Okaniwa G, Nakada T, Fujimura S. Effects of hypothermia and hyperpotassium on alveolar fluid clearance in the resected human lung. Surg Today 1995; 25:694-700. [PMID: 8520163 DOI: 10.1007/bf00311485] [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: 01/31/2023]
Abstract
The effect of hypothermia and hyperpotassium on alveolar fluid clearance in the resected human lung was examined by instilling an isosmotic albumin solution with a potassium concentration of 0.3 mEq/l or 20 mEq/l into one segment of a resected lobe within 10 min of surgical removal for bronchogenic carcinoma. The experiments were carried out at 37 degrees C, 25 degrees C, and and 8 degrees C over 4 hr, after which the alveolar fluid was aspirated. Alveolar fluid clearance was calculated by a simple equation using the changes in the albumin concentration of the alveolar fluid. It was found that although hypothermia at 8 degrees C abolished alveolar fluid clearance completely, alveolar fluid clearance at 25 degrees C was not different from that at 37 degrees C. Moreover, although the potassium concentration increased in the alveolar fluid at 37 degrees C and 8 degrees C, hyperpotassium did not affect the alveolar fluid clearance. These findings indicate that the net transport of potassium leans to influx from the alveolar epithelial cells into the alveolar spaces when the alveolar potassium concentration is low, and to efflux from the alveolar spaces when the alveolar potassium concentration is high. Thus, we conclude that hypothermia abolishes alveolar fluid clearance in resected human lungs, but that the potassium concentration in alveolar fluid does not affect alveolar fluid clearance.
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Affiliation(s)
- T Sakuma
- Department of Surgery, Sendai Kosei Hospital, Japan
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Fyfe GK, Kemp PJ, Cragoe EJ, Olver RE. Conductive cation transport in apical membrane vesicles prepared from fetal lung. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1224:355-64. [PMID: 7803490 DOI: 10.1016/0167-4889(94)90268-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In order to characterise the apically-located conductive cation pathway of the type II pneumocyte, apical plasma membranes were prepared from mature fetal guinea pig lung. The protocol yielded purified apical membranes that enriched 19-fold with the brush border enzyme marker alkaline phosphatase; there was no significant contamination with other cellular membranes. A technique for imposing an outwardly-directed electrochemical Na+ gradient was used to amplify conductive 22Na+ uptake into vesicles. Uptake of 22Na+ was time-dependent, proportional to the magnitude of the Na+ gradient, specific and sensitive to the amiloride analogues phenamil and EIPA (apparent minimum Ki values of 50 nM and 10 microM, respectively, with maximum uptake inhibition of 42% and 39% at 100 microM). Uptake experiments in which the outwardly-directed Na+ gradient was replaced by outwardly-directed gradients of small monovalent cations and molecular cations were performed. The Na+/K+ permeability ratio was 1.2:1, and over the extended range of small monovalent cations, a permeability sequence of Na+ > K+ > Li+ > Rb+ > Cs+ was observed, indicating the presence of fixed negative charge in or spatially close to the pore. The molecular cation permeability sequence of NH4+ > methylamine+ > dimethylamine+ > choline+ > N-methyl-D-glucamine+ > tetraethylammonium+ > tetramethylammonium+, after transformation, gives an estimate of 8 A for the conducting pore diameter. These data are consistent with the presence in the apical membrane of fetal type II pneumocytes of a cation specific channel with low Na+ selectivity and amiloride sensitivity.
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Affiliation(s)
- G K Fyfe
- Department of Child Health, Centre for Research into Human Development, Ninewells Hospital and Medical School, University of Dundee, UK
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Affiliation(s)
- M A Matthay
- Cardiovascular Research Institute, University of California, San Francisco 94143-0130
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Abstract
Airway surface liquid (ASL) is an integral part of lung defense mechanisms. Ion transport by airway epithelia regulates the volume and composition of this fluid. A better understanding of the mechanisms of ion transport will enable the development of new therapies for airway diseases associated with defects in these mechanisms. A useful model of a disease with abnormal airway epithelial ion transport is cystic fibrosis (CF), a distinct genetic syndrome of altered lung defense mechanisms characterized by chronic bacterial infection and a steady decline in lung function. Traditional therapies for CF include antibacterial drugs and augmentation of clearance of secretions, but investigators are now studying pharmacological approaches to target the more basic defect of the disease, i.e. abnormal sodium and chloride ion transport. Early treatment in childhood, prior to lung damage, might prevent or at least retard the decline in pulmonary function that remains the hallmark of CF. Ion transport dysfunction may also contribute to other airway diseases such as asthma and chronic bronchitis. Pharmacological intervention at this level may prove beneficial in these common lung diseases as well.
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Affiliation(s)
- P G Noone
- Department of Medicine, University of North Carolina at Chapel Hill 27599-7020
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Oelberg DG, Xu F, Shabarek F. Sodium/proton transport by apical membranes of type-II pneumocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1149:19-28. [PMID: 8391318 DOI: 10.1016/0005-2736(93)90020-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Recent studies fail to confirm the coexistence of Na+ channels and Na+/H+ exchange at the apical membranes of lower airway epithelia. Availability of plasma membrane vesicles simplifies the investigation of membrane transport processes. Apical and basolateral plasma membrane vesicles of disrupted type-II pneumocytes were fractionated upon nonlinear, continuous sucrose gradients. To investigate sodium transport, 22Na+ uptake by apical membrane vesicles was assayed in the presence and absence of transmembrane sodium diffusion potentials. Interior-negative sodium diffusion potentials promoted 22Na+ uptake 1.5-fold. Internally-directed H+ gradients or NH+4 gradients inhibited 22Na+ uptake 40-50%. Amiloride (1-1000 microM) inhibited uptake 10-79%. To investigate H+ transport, decay of transmembrane pH gradients was monitored with pH probe acridine orange. In the presence or absence of externally-directed H+ gradients, external sodium promoted internal alkalinization, except in the presence of external amiloride. These observations of amiloride-sensitive, electrogenic Na+ uptake and amiloride-sensitive, electroneutral, Na+/H+ coupling indicate coexistence of Na+ channels and Na+/H+ exchange at the apical membrane of type-II pneumocytes.
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Affiliation(s)
- D G Oelberg
- Department of Pediatrics, University of Texas Health Science Center, Houston
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McLaughlin GE, Kim KJ, Berg MM, Agoris P, Lubman RL, Crandall ED. Measurement of solute fluxes in isolated rat lungs. RESPIRATION PHYSIOLOGY 1993; 91:321-34. [PMID: 8469854 DOI: 10.1016/0034-5687(93)90109-n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Most previous studies in isolated perfused lungs have utilized measurements of solute flow from alveolar to vascular space to characterize the barrier and transport properties of the alveolar epithelium. In this study, we measured flux of a series of nonionic hydrophilic solutes and sodium across the alveolar epithelium of the isolated rat lung from perfusate to airspace (P-->A), as well as from airspace to perfusate (A-->P). Apparent permeability-surface area products (PS) were calculated from the rates of isotope appearance downstream in either the airspace or the perfusate. Equivalent pore analysis of data for P-->A solute flow demonstrated a small pore population with radius 0.6 nm occupying 85% of the total pore area and a large pore population with radius 3.8 nm occupying 15% of the total area. Similar analysis of A-->P solute flux demonstrated a small pore population of 0.6 nm occupying 86% of the total pore area and a large pore population with radius 2.9 nm occupying 14% of total pore area. The ratio (R) of PSP-->A divided by PSA-->P was 0.8 for the nonionic hydrophilic solutes, while R for sodium was 0.5. In the presence of amiloride and ouabain, R for sucrose was unchanged while R for sodium increased to 0.8 due to a fall in PSA-->P. The difference between R for sodium and R for the passively transported solutes, and the reduction in this difference in the presence of sodium transport inhibitors, are consistent with active sodium reabsorption by the intact alveolar epithelium. Differences in measured unidirectional passive solute fluxes probably result from unequal effective surface areas for diffusion from vascular space to airspace and vice versa in the anatomically complex mammalian lung.
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42
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Danto SI, Zabski SM, Crandall ED. Reactivity of alveolar epithelial cells in primary culture with type I cell monoclonal antibodies. Am J Respir Cell Mol Biol 1992; 6:296-306. [PMID: 1540393 DOI: 10.1165/ajrcmb/6.3.296] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
An understanding of the process of alveolar epithelial cell growth and differentiation requires the ability to trace and analyze the phenotypic transitions that the cells undergo. This analysis demands specific phenotypic probes to type II and, especially, type I pneumocytes. To this end, monoclonal antibodies have been generated to type I alveolar epithelial cells using an approach designed to enhance production of lung-specific clones from a crude lung membrane preparation. The monoclonal antibodies were screened by a combination of enzyme-linked immunosorbent assay and immunohistochemical techniques, with the determination of type I cell specificity resting primarily on immunoelectron microscopic localization. Two of these new markers of the type I pneumocyte phenotype (II F1 and VIII B2) were used to analyze primary cultures of type II cells growing on standard tissue culture plastic and on a variety of substrata reported to affect the morphology of these cells in culture. On tissue culture plastic, the antibodies fail to react with early (days 1 to 3) type II cell cultures. The cells become progressively more reactive with time in culture to a plateau of approximately 6 times background by day 8, with a maximum rate of increase between days 3 and 5. This finding is consistent with the hypothesis that type II cells in primary culture undergo at least partial differentiation into type I cells. Type II cells grown on laminin, which reportedly delays the loss of type II cell appearance, and on fibronectin, which has been reported to facilitate cell spreading and loss of type II cell features, develop the type I cell markers during cultivation in vitro with kinetics similar to those on uncoated tissue culture plastic. Cells on type I collagen and on tissue culture-treated Nuclepore filters, which have been reported to support monolayers with type I cell-like morphology, also increase their expression of the II F1 and VIII B2 epitopes around days 3 to 5. Taken together with available morphologic information, these data suggest that expression of different alveolar epithelial cell phenotypic markers by type II cells in primary culture may be independently regulated. The monoclonal antibody probes described in this report should prove useful in the continued investigation of the mechanisms and regulation of alveolar epithelial cell differentiation.
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Affiliation(s)
- S I Danto
- Will Rogers Institute Pulmonary Research Center, Division of Pulmonary and Critical Care Medicine, University of Southern California, Los Angeles 90033
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Achouche J, Liu DS, Tran Ba Huy P, Huy PT. Primary culture of strial marginal cells of guinea pig cochlea: growth, morphologic features, and characterization. Ann Otol Rhinol Laryngol 1991; 100:999-1006. [PMID: 1720935 DOI: 10.1177/000348949110001208] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To further investigate the cellular mechanisms involved in the formation of endolymph, primary cultures of marginal cells of guinea pig were established. Minute explants obtained by mechanical dissociation of stria vascularis were plated on collagen type I precoated impermeable substrate in serum-free, hormone-supplemented medium. A confluent layer of epithelial-like cells was obtained within 2 weeks. The cultured cells formed domes, demonstrating that they retain some of their transepithelial properties. Polarization was also suggested by electron microscopic observation of apical microvilli and tight junctions. Immunohistochemical methods revealed that the cultured cells coexpressed cytokeratin and vimentin, demonstrating their epithelial origin, although some degree of dedifferentiation occurred. Thus, a primary culture of marginal cells can be established that may be a suitable model for an in-depth investigation of the function of the marginal cells.
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Affiliation(s)
- J Achouche
- Faculty Villemin-Lariboisière-Saint-Louis, Paris, France
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Sznajder JI, Wood LD. Beneficial effects of reducing pulmonary edema in patients with acute hypoxemic respiratory failure. Chest 1991; 100:890-2. [PMID: 1914601 DOI: 10.1378/chest.100.4.890] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Clerici C, Soler P, Saumon G. Sodium-dependent phosphate and alanine transports but sodium-independent hexose transport in type II alveolar epithelial cells in primary culture. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1063:27-35. [PMID: 2015259 DOI: 10.1016/0005-2736(91)90349-d] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inorganic phosphate, amino acids and sugars are of obvious importance in lung metabolism. We investigated sodium-coupled transports with these organic and inorganic substrates in type II alveolar epithelial cells from adult rat after one day in culture. Alveolar type II cells actively transported inorganic phosphate and alanine, a neutral amino acid, by sodium-dependent processes. Cellular uptakes of phosphate and alanine were decreased by about 80% by external sodium substitution, inhibited by ouabain (30 and 41%, respectively) and displayed saturable kinetics. Two sodium-phosphate cotransport systems were characterized: a high-affinity one (apparent Km = 18 microM) with a Vmax of 13.5 nmol/mg protein per 10 min and a low-affinity one (apparent Km = 126 microM) with a Vmax of 22.5 nmol/mg protein per 10 min. Alanine transport had an apparent Km of 87.9 microM and a Vmax of 43.5 nmol/mg protein per 10 min. By contrast, cultured alveolar type II cells did not express sodium-dependent hexose transport. Increasing time in culture decreased Vmax values of the two phosphate transport systems on day 4 while sodium-dependent alanine uptake was unchanged. This study demonstrated the existence of sodium-dependent phosphate and amino acid transports in alveolar type II cells similar to those documented in other epithelial cell types. These sodium-coupled transports provide a potent mechanism for phosphate and amino acid absorption and are likely to play a role in substrate availability for cellular metabolism and in regulating the composition of the alveolar subphase. The decrease in phosphate uptake with time in culture is parallel to decrease in surfactant synthesis reported in cultured alveolar type II cells, suggesting that phosphate availability for surfactant synthesis may be accomplished by a sodium-dependent phosphate uptake.
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Affiliation(s)
- C Clerici
- INSERM U82, Faculté de médecine Xavier Bichat, Université Paris 7, France
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Nici L, Dowin R, Gilmore-Hebert M, Jamieson JD, Ingbar DH. Response of rat type II pneumocyte Na,K-ATPase to hyperoxic injury. Chest 1991; 99:31S-33S. [PMID: 1705195 DOI: 10.1378/chest.99.3_supplement.31s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- L Nici
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510
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Barker PM, Walters DV, Markiewicz M, Strang LB. Development of the lung liquid reabsorptive mechanism in fetal sheep: synergism of triiodothyronine and hydrocortisone. J Physiol 1991; 433:435-49. [PMID: 1841951 PMCID: PMC1181381 DOI: 10.1113/jphysiol.1991.sp018436] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. Thyroidectomy was performed on twelve fetal sheep between 111 and 115 days gestation. Measurement of fetal lung liquid secretion and absorption rates (Jv) were made at rest and during short (45 min) and long (5 h) infusions of adrenaline (0.5 micrograms/min) in a total of thirty-seven experiments, some in the absence of triiodothyronine (T3) and hydrocortisone and some at set times after the administration of the two hormones. 2. T3 was given either as an I.V. infusion (60 micrograms/24 h) or as a bolus of 30 micrograms; hydrocortisone was given as an infusion of 10 mg/24 h. Both hormones were administered together. 3. Before T3 and hydrocortisone were given short infusions of adrenaline had no effect on Jv but 4 h after exposure to the hormones secretion rate was reduced to near zero (Jv = -0.5 +/- 1.6 ml/h, n = 4) by adrenaline; after 24 h of hormone exposure, absorption of fetal lung liquid was produced by adrenaline (Jv = -3.6 +/- 2.2 ml/h, n = 4) which was even greater after 72 h, (Jv = -11.2 +/- 2.2 ml/h, n = 4). 4. During long infusions of adrenaline when T3 and hydrocortisone were given at the start of the experiment, an effect on lung liquid secretion was evident at 2 h and absorption was produced at 4 h (Jv = -4.2 +/- 2.5 ml/h, n = 3). The effect was significantly different from control long infusions of adrenaline performed the previous day in the absence of hormones. 5. After 24 or 48 h of stopping T3 and hydrocortisone administration, adrenaline no longer produced absorption of lung liquid, indicating that the effect of the two hormones was reversible within 24-48 h. 6. The protein synthesis inhibitor cycloheximide put into lung liquid (4 x 10(-5) to 3 x 10(-4) M) blunted the effect of the hormones at 4 h and prevented absorption of lung liquid at 24 h. Jv during adrenaline was -3.6 +/- 1.5 ml/h in control experiments but was +3.3 +/- 0.9 ml/h after cycloheximide, n = 4, P < 0.01. This indicated that the two hormones produced their effect through protein synthesis.
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Affiliation(s)
- P M Barker
- Department of Paediatrics, University College and Middlesex School of Medicine, Rayne Institute, London
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Matthay MA, Wiener-Kronish JP. Intact epithelial barrier function is critical for the resolution of alveolar edema in humans. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1990; 142:1250-7. [PMID: 2252240 DOI: 10.1164/ajrccm/142.6_pt_1.1250] [Citation(s) in RCA: 409] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Within 15 min of endotracheal intubation, the resolution of pulmonary edema was studied over the next 12 h in 34 mechanically ventilated patients by (1) serial measurements of the alveolar-arterial oxygen difference, (2) the extent of edema on the initial and follow-up chest radiograph, and (3) by an initial and final measurement of total protein and albumin concentration in sequential samples of pulmonary edema fluid. Based on the oxygenation and chest radiographic data, 24 patients clinically improved and 10 patients did not improve. In the 10 patients who did not clinically improve (3, hydrostatic edema; 7, permeability edema), there was no change in the final edema fluid protein concentration (4.1 +/- 1.1 g/100 ml) compared with the initial edema fluid protein concentration (4.2 +/- 1.0 g/100 ml) (p = ns). However, in the 24 patients who clinically improved (15, hydrostatic edema; 9, permeability edema), there was an increase in every patient's final edema protein concentration (5.6 +/- 2.3 g/100 ml) compared with their initial edema protein concentration (3.8 +/- 1.2 g/100 ml) (p less than 0.01). In 13 of these 24 patients, the final edema fluid concentration (7.3 +/- 1.6 g/100 ml) exceeded the final plasma protein concentration (5.6 +/- 0.8 g/100 ml) by a mean value of 1.7 g/100 ml protein. The data provide the first evidence in humans to support the hypothesis that active ion transport across the alveolar epithelial barrier is the primary mechanism for clearance of edema fluid from the air spaces of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M A Matthay
- Department of Medicine, University of California, San Francisco 94143
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49
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Cheek JM, Kim KJ, Crandall ED. NO2 decreases paracellular resistance to ion and solute flow in alveolar epithelial monolayers. Exp Lung Res 1990; 16:561-75. [PMID: 2081503 DOI: 10.3109/01902149009087880] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Primary cultured monolayers of rat alveolar epithelial cells grown on tissue culture-treated Nuclepore filters were exposed to 2.5 ppm nitrogen dioxide (NO2) for 2-20 min. Changes in monolayer bioelectric properties and solute permeabilities were subsequently measured. Exposure to NO2 produced a dose-dependent decrease in monolayer transepithelial electrical resistance (Rt), whereas monolayer short-circuit current was unaffected. Post-exposure monolayer permeability to 14C-sucrose (which primarily crosses alveolar epithelium via the paracellular pathway) increased markedly. That for 3H-glycerol (which permeates through both paracellular and transcellular pathways) increased to a lesser extent. Partial recovery of Rt and solute permeabilities was noted by 48-h post-exposure. The time courses of the decrease in Rt and increase in solute permeabilities were similar. These results suggest that NO2 primarily impairs passive alveolar epithelial barrier functions in vitro, probably by altering intercellular junctions, and does not appear to directly affect cell membrane active ion transport processes. When correlated with results obtained from experimental approaches, studies of in vitro alveolar epithelial monolayers may facilitate investigations of dosimetry, sites, and mechanisms of oxidant injury in the lung.
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Affiliation(s)
- J M Cheek
- Seaver Cardiopulmonary Laboratory, Will Rogers Institute Pulmonary Research Program, Cornell University Medical College, New York, New York
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50
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Barker PM, Strang LB, Walters DV. The role of thyroid hormones in maturation of the adrenaline-sensitive lung liquid reabsorptive mechanism in fetal sheep. J Physiol 1990; 424:473-85. [PMID: 2391659 PMCID: PMC1189824 DOI: 10.1113/jphysiol.1990.sp018078] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
1. Following thyroidectomy at 106-118 days fetal sheep were infused continuously with triiodothyronine (T3) from 110, 118, 125 or 131 days (n = 12) or with thyroxine (T4) from 118 days (n = 4) until the fetuses were delivered. Lung liquid secretion or absorption rates, heart rate, blood pressure and arterial blood gases were measured before and during 45 min periods of fetal infusions of adrenaline (n = 60) at 3-8 day intervals. The effects of T3 or T4 replacement on the response to adrenaline were compared with data previously obtained in groups of euthyroid (control) and thyroidectomized (Tx) fetuses. 2. Fetuses infused with T4 (50 micrograms/day) following thyroidectomy had plasma T4 and T3 concentrations in the normal fetal range. Fetal plasma T3 levels in fetuses infused with T3 (60 micrograms/day) were at or above the high end of the normal range for full-term fetuses. Those receiving 120 micrograms of T3 per day had levels equivalent to those normally seen in the postnatal T3 surge. 3. Normal maturation in the lung of the reabsorptive response of fetal lung liquid to adrenaline was seen in the fetuses infused with T3 or T4 from 118 days. A marginal advance in maturation was seen in fetuses infused with T3 from 110 days and a delay in maturation in those infused with T3 from 125 and 131 days.
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Affiliation(s)
- P M Barker
- Department of Paediatrics, Rayne Institute, University College and Middlesex Medical School, London
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