Putrescine uptake in hamster lung slices and primary cultures of type II pneumocytes

1995 ◽  
Vol 269 (5) ◽  
pp. L681-L689 ◽  
Author(s):  
P. H. Hoet ◽  
C. P. Lewis ◽  
D. Dinsdale ◽  
M. Demedts ◽  
B. Nemery
Keyword(s):  
Cellular Localization ◽  
Competitive Inhibition ◽  
Primary Cultures ◽  
Alveolar Epithelium ◽  
Type I ◽  
Uptake System ◽  
Type Ii ◽  
Active Uptake ◽  
Type Ii Pneumocytes ◽  
Discontinuous Percoll Gradient

Putrescine is accumulated in the lungs of various species by an active uptake system that also mediates the uptake of cystamine and paraquat. We have characterized this uptake in both lung slices and type II pneumocytes isolated from hamsters by trypsin digestion, differential adherence on plastic, and centrifugation on a discontinuous Percoll gradient. The accumulation of [14C]putrescine in lung slices was shown to be temperature and energy dependent, and to obey saturation kinetics, with mean calculated values of apparent Michaelis constant (Km) 29.4 microM and maximum rate of uptake (Vmax) 637 nmol.g-1.h-1. In the presence of cystamine or paraquat, the putrescine uptake was reduced in a manner compatible with competitive inhibition. The calculated inhibitor constants (Ki) were 16 and 1,017-1,328 microM for the inhibition by cystamine and paraquat, respectively. The cellular localization of [3H]putrescine in lung slices after incubation with 2.5 microM putrescine was determined by light-microscopic autoradiography. Labeling was present in type II and possibly also in type I pneumocytes of the alveolar epithelium but not in macrophages, endothelium, or cells of the interstitium. Two days after their isolation, cultured type II pneumocytes exhibited an uptake of putrescine that had kinetic characteristics similar to those of slices (Km of 23 microM and Vmax of 3.06 mumol.g protein-1.h-1) and was also competitively inhibited by paraquat (Ki of 222-350 microM paraquat). Our data demonstrate the presence of an active uptake system for putrescine in both lung slices and cultured type II pneumocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Histo-Morphology Study of the Respiratory Portion of Goat Lung (Capra Hircus) in Baghdad Province

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Noor Yousif
Keyword(s):  
Epithelial Cells ◽  
Squamous Epithelium ◽  
Alveolar Epithelium ◽  
Clara Cell ◽  
Capra Hircus ◽  
Type I ◽  
Type Ii ◽  
Type Ii Pneumocytes ◽  
Pulmonary Parenchyma ◽  
I Cells

The Histo-mrphology were directed on the pneumonic alveoli of 6 male goats. The respiratory portion is composed of typical cuboidal epithelial cells with Clara cell, however, alveolar ducts are lined by simple squamous epithelium and alveoli were generally circular structures that opened into the alveolar conduits and alveolar sacs or respiratory bronchioles. Alveoli were made out of two kinds of cells for example Type-I pneumocytes and Type-II pneumocytes. Previous framed the mainlining epithelial cells of alveoli which were squamous in sort having noticeable perinuclear territory and central found the core, while the last were cuboidal fit as a fiddle with the midway found core and periodically found among the Sort I cells in the alveolar epithelium. The lung pulmonary parenchyma was enveloped by the mesothelium (squamous epithelium) layer of visceral pleura.

Development of type II pneumocytes in rat lung

1991 ◽  
Vol 260 (2) ◽  
pp. L113-L122 ◽  
Author(s):  
S. L. Young ◽  
E. K. Fram ◽  
C. L. Spain ◽  
E. W. Larson
Keyword(s):  
Three Dimensional ◽  
Alveolar Epithelium ◽  
Type Ii Cells ◽  
Type Ii ◽  
Time Period ◽  
Type Ii Pneumocytes ◽  
Type Ii Cell ◽  
Membrane Type ◽  
Cytoplasmic Processes ◽  
Homogenous Population

At a late stage of fetal development, the mammalian alveolar epithelium undergoes an abrupt differentiation as a part of the preparation of the lung for the postnatal demands of gas exchange. Some of the most striking changes occur in the type II pneumocytes as they lose their glycogen and start to produce the lamellated inclusion granules that contain pulmonary surfactant. Premature birth before adequate type II cell maturation results in the neonatal respiratory distress syndrome, which is frequently fatal. We have used serial ultrathin sectioning, electron microscopy, and three-dimensional reconstructions to study the ultrastructural features of maturation of rat type II cells from a single rat each at age gestational day 20 through adult stages. We found evidence over this time span for compartmentation of several secretory granule precursors within type II cells. Changes in the polarization of lamellar bodies were observed over the time period studied. We also found marked gestational changes in the number and morphology of type II cell cytoplasmic processes that perforate the basement membrane. Type II cell mitochondria changed in shape during postnatal development from single, spherical to complex, branched structures. Volume composition obtained from serial sections of a small number of type II cells agreed closely with published morphometric data, indicating that throughout the animal's lifespan, type II cells are a homogenous population.

Effect of tunicamycin on maturation of fetal mouse lung

1993 ◽  
Vol 265 (3) ◽  
pp. L250-L259
Author(s):  
E. H. Webster ◽  
S. R. Hilfer ◽  
R. L. Searls ◽  
J. Kornilow
Keyword(s):  
Extracellular Matrix ◽  
Fetal Lung ◽  
Mouse Lung ◽  
Type I ◽  
Type Ii ◽  
Fetal Mouse ◽  
Type Ii Pneumocytes ◽  
Separate Control ◽  
Normal Controls

The mesodermal capsule of the fetal lung plays a role in differentiation of the respiratory region. It has been proposed for other epithelial organs that the mesodermal capsule influences development by modifying the basal lamina or the extended extracellular matrix. The effect could be on deposition or turnover of collagens, proteoglycans, and/or glycoproteins. This study tests the role of glycoproteins in differentiation of respiratory endings by inhibiting their synthesis with the antibiotic tunicamycin (TM). Lungs at 16 and 18 days gestation and 3 days after birth were cultured with TM and examined for morphological and biochemical differences from normal controls. With TM, alveolar regions did not expand properly and formed fewer type I pneumocytes, although type II pneumocytes were unaffected. The epithelium of untreated respiratory regions showed greater incorporation of radioactive mannose than the airways region or mesenchyme. This incorporation was diminished in TM, but the pattern persisted. Comparison with the results obtained with beta-xyloside suggested that differentiation of type I and type II pneumocytes is under separate control.

Mechanisms and regulation of ion transport in adult mammalian alveolar type II pneumocytes

1991 ◽  
Vol 261 (5) ◽  
pp. C727-C738 ◽  
Author(s):  
S. Matalon
Keyword(s):  
Epithelial Transport ◽  
Cultured Cells ◽  
Basolateral Membrane ◽  
Alveolar Epithelium ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii ◽  
Epithelial Lining ◽  
Epithelial Lining Fluid

The adult alveolar epithelium consists of type I and type II (ATII) pneumocytes that form a tight barrier, which severely restricts the entry of lipid-insoluble molecules from the interstitial to the alveolar space. Current in vivo and in vitro evidence indicates that the alveolar epithelium is also an absorptive epithelium, capable of transporting Na+ from the alveolar lumen, which is bathed by a small amount of epithelial lining fluid, to the interstitial space. The in situ localization of Na(+)-K(+)-ATPase activity in ATII cells and the fact that these cells are involved in a number of crucial functions, such as surfactant secretion and alveolar remodeling after injury, led investigators to examine their transport characteristics. Radioactive flux studies, in both freshly isolated and cultured cells, and bioelectric measurements in ATII cells grown on porous supports indicate that they transport Na+ according to the Koefoed-Johnsen and Ussing model of epithelial transport. Na+ enters the apical membrane, because of the favorable electrochemical gradient, through Na+ cotransporters, a Na(+)-H+ antiport, and cation channels and is pumped across the basolateral membrane by a ouabain-sensitive Na(+)-K+ pump. Na+ transport is enhanced by substances that increase intracellular adenosine 3',5'-cyclic monophosphate. In addition to Na+ transporters, ATII cells contain several transporters that regulate their intracellular pH, including a H(+)-ATPase, which may explain the low pH of the epithelial lining fluid. The absorptive properties of ATII cells may play an important role in regulating the degree of alveolar fluid in health and disease.

scholarly journals Hypoxia regulates gene expression of alveolar epithelial transport proteins

2000 ◽  
Vol 88 (5) ◽  
pp. 1890-1896 ◽  
Author(s):  
Christine Clerici ◽  
Michael A. Matthay
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Alveolar Epithelium ◽  
Transport Proteins ◽  
Alveolar Epithelial Cells ◽  
Type I ◽  
Type Ii ◽  
Atp Content ◽  
Glut 1 ◽  
Alveolar Epithelial

Alveolar hypoxia occurs during ascent to high altitude but is also commonly observed in many acute and chronic pulmonary disorders. The alveolar epithelium is directly exposed to decreases in O2tension, but a few studies have evaluated the effects of hypoxia on alveolar cell function. The alveolar epithelium consists of two cell types: large, flat, squamous alveolar type I and cuboidal type II (ATII). ATII cells are more numerous and have a number of critical functions, including transporting ions and substrates required for many physiological processes. ATII cells express 1) membrane proteins used for supplying substrates required for cell metabolism and 2) ion transport proteins such as Na+channels and Na+-K+-ATPase, which are involved in the vectorial transport of Na+from the alveolar to interstitial spaces and therefore drive the resorption of alveolar fluid. This brief review focuses on gene expression regulation of glucose transporters and Na+transport proteins by hypoxia in alveolar epithelial cells. Cells exposed to severe hypoxia (0% or 3% O2) for 24 h upregulate the activity and expression of the glucose transporter GLUT-1, resulting in preservation of ATP content. Hypoxia-induced increases in GLUT-1 mRNA levels are due to O2deprivation and inhibition of oxidative phosphorylation. This regulation occurs at the transcriptional level through activation of a hypoxia-inducible factor. In contrast, hypoxia downregulates expression and activity of Na+channels and Na+-K+-ATPase in cultured alveolar epithelial cells. Hypoxia induces time- and concentration-dependent decreases of α-, β-, and γ-subunits of epithelial Na+channel mRNA and β1- and α1-subunits of Na+-K+-ATPase, effects that are completely reversed after reoxygenation. The mechanisms by which O2deprivation regulates gene expression of Na+transport proteins are not fully elucidated but likely involve the redox status of the cell. Thus hypoxia regulates gene expression of transport proteins in cultured alveolar epithelial type II cells differently, preserving ATP content.

Unique Structural Features That Influence Neutrophil Emigration Into the Lung

2003 ◽  
Vol 83 (2) ◽  
pp. 309-336 ◽  
Author(s):  
Alan R. Burns ◽  
C. Wayne Smith ◽  
David C. Walker
Keyword(s):  
Alveolar Epithelium ◽  
Structural Features ◽  
Alveolar Epithelial Cells ◽  
Alveolar Wall ◽  
Type I ◽  
Type Ii ◽  
Alveolar Epithelial ◽  
Capillary Bed ◽  
Vascular Beds ◽  
Alveolar Capillary

Neutrophil emigration in the lung differs substantially from that in systemic vascular beds where extravasation occurs primarily through postcapillary venules. Migration into the alveolus occurs directly from alveolar capillaries and appears to progress through a sequence of steps uniquely influenced by the cellular anatomy and organization of the alveolar wall. The cascade of adhesive and stimulatory events so critical to the extravasation of neutrophils from postcapillary venules in many tissues is not evident in this setting. Compelling evidence exists for unique cascades of biophysical, adhesive, stimulatory, and guidance factors that arrest neutrophils in the alveolar capillary bed and direct their movement through the endothelium, interstitial space, and alveolar epithelium. A prominent path accessible to the neutrophil appears to be determined by the structural interactions of endothelial cells, interstitial fibroblasts, as well as type I and type II alveolar epithelial cells.

Type II pneumocyte proliferation in vitro: problems and future directions

1991 ◽  
Vol 261 (4) ◽  
pp. L110-L117 ◽  
Author(s):  
Bruce D. Uhal ◽  
Kevin M. Flowers ◽  
D. Eugene Rannels
Keyword(s):  
Cell Cycle ◽  
Primary Culture ◽  
Alveolar Epithelium ◽  
Preliminary Evaluation ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Type Ii Pneumocyte ◽  
Cell Cycle Block

In adult animals, the type II pneumocyte is progenitor of both the type I and type II alveolar epithelium. In primary culture, however, the fate of this cell is uncertain. Type II cells in culture lose their differentiated properties and eventually resemble type I cells, but a lack of specific markers has complicated the characterization of the phenotype acquired in vitro. Furthermore, limited proliferation of these cells in vitro has precluded definition of the relationship between type II cell proliferation and differentiation. Recent work in this laboratory has involved the correlation of flow cytometric cell cycle analysis with phenotype markers. Initial results indicate that isolation of type II cells induces cell cycle block similar to that sustained by other cell types in response to stress. In addition, preliminary evaluation of phenotype suggests that traditional markers become ambiguous beyond the 1st day of primary culture. These results raise concern related to the interpretation of experiments conducted in vitro. This report discusses the implications of these findings and directions for future work. alveolar epithelium; bromodeoxyuridine; cell cycle block; flow cytometry; lung injury

Alveolar epithelial cells in vitro produce gelatinases and tissue inhibitor of matrix metalloproteinase-2

1997 ◽  
Vol 273 (3) ◽  
pp. L663-L675 ◽  
Author(s):  
M. P. d'Ortho ◽  
C. Clerici ◽  
P. M. Yao ◽  
C. Delacourt ◽  
C. Delclaux ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Matrix Metalloproteinase ◽  
Primary Cultures ◽  
Basement Membranes ◽  
Alveolar Epithelial Cells ◽  
Matrix Metalloproteinase 2 ◽  
Type Ii ◽  
Matrix Metalloproteinase 1 ◽  
Type Ii Pneumocytes

Type II pneumocytes are key cells of the alveolar epithelium. They lie on the alveolar basement membrane, which influences their phenotype and functions. We hypothesized that type II pneumocytes degrade basement membrane components by producing gelatinases, members of the matrix metalloproteinase family. To investigate this hypothesis, we used primary cultures of rat type II pneumocytes and cultures of the human A549 cell line. We found by zymography that 70-kDa gelatinase was present in media conditioned by these cells. This 70-kDa gelatinase was identified as gelatinase A by a Western blot, and the presence of its mRNA was demonstrated by reverse transcription-polymerase chain reaction. A 95-kDa gelatinase could be induced under certain conditions. Production of gelatinases may take place during the turnover of basement membranes, in physiological and in pathophysiological processes. This was suggested by the increase in production of both gelatinases that we observed after in vitro exposure to LPS or interleukin-1. The presence of tissue inhibitors of matrix metalloproteinase-1 and -2 was also demonstrated, suggesting that degradation of extracellular matrix by type II pneumocytes is tightly regulated.

Amiloride-sensitive Na+ channels in fetal type II pneumocytes are regulated by G proteins

1994 ◽  
Vol 267 (1) ◽  
pp. L1-L8 ◽  
Author(s):  
G. G. MacGregor ◽  
R. E. Olver ◽  
P. J. Kemp
Keyword(s):  
Single Channel ◽  
Alveolar Epithelium ◽  
Single Channels ◽  
Type Ii ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Channel Current ◽  
Type Ii Pneumocytes ◽  
Rich Solution ◽  
Differential Filtration

We have used the patch-clamp technique to record single channels in excised membrane patches from type II pneumocytes freshly isolated from fetal guinea pig lung by elastase digestion and differential filtration. The 10/56 patches exhibited spontaneous channel activity with a mean open-state probability (NPo) of 0.5 +/- 0.1. In symmetrical Na(+)-rich solutions, the channels had a unitary conductance of 11.1 +/- 0.5 pS and showed current reversal at approximately 0 mV. Superfusing the inner membrane leaflet of the patch with a K(+)-rich solution resulted in single-channel current activity with a conductance of 5.6 +/- 0.2 pS being resolved. Current reversed at +22.1 +/- 1.9 mV, which is compatible with a PNa+/PK+ of 1.8 +/- 0.1. The addition of 0.1 mM guanosine 5'-O-(3-thiotriphosphate) to the cytoplasmic face of the patch elicited channel activity in 12/31 previously quiescent patches, whereas, in spontaneously active patches, channel NPo was increased. Amiloride, in the concentration range 0.4-4 microM, reduced the frequency of observed spontaneous (or activatable) channel activity, reduced NPo, and induced flickery channel behavior. No activity was seen in the presence of 10 microM amiloride in the pipette. This is the first direct observation of a G protein regulated Na(+)-conductive pathway in alveolar epithelium, and it may represent one route by which the alveolar epithelium of the fetus can regulate the Na(+)-driven fluid reabsorption necessary for the adaptation of the newborn lung to air breathing at birth.

scholarly journals CD44high alveolar type II cells show stem cell properties during steady-state alveolar homeostasis

2017 ◽  
Vol 313 (1) ◽  
pp. L41-L51 ◽  
Author(s):  
Qian Chen ◽  
Varsha Suresh Kumar ◽  
Johanna Finn ◽  
Dianhua Jiang ◽  
Jiurong Liang ◽  
...  
Keyword(s):  
Alveolar Epithelium ◽  
Cell Subpopulation ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Cell Surface Molecule ◽  
Type I Cells ◽  
Blood Exchange ◽  
I Cells

The alveolar epithelium is composed of type I cells covering most of the gas-blood exchange surface and type II cells secreting surfactant that lowers surface tension of alveoli to prevent alveolar collapse. Here, we have identified a subgroup of type II cells expressing a higher level of cell surface molecule CD44 (CD44high type II cells) that composed ~3% of total type II cells in 5–10-wk-old mice. These cells were preferentially apposed to lung capillaries. They displayed a higher proliferation rate and augmented differentiation capacity into type I cells and the ability to form alveolar organoids compared with CD44low type II cells. Moreover, in aged mice, 18–24 mo old, the percentage of CD44high type II cells among all type II cells was increased, but these cells showed decreased progenitor properties. Thus CD44high type II cells likely represent a type II cell subpopulation important for constitutive regulation of alveolar homeostasis.

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