A noninducible cystine transport system in rat alveolar type II cells

1995 ◽  
Vol 268 (1) ◽  
pp. L21-L26 ◽  
Author(s):  
D. M. Bukowski ◽  
S. M. Deneke ◽  
R. A. Lawrence ◽  
S. G. Jenkinson
Keyword(s):  
Transport System ◽  
Cell Types ◽  
Lung Epithelial Cells ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lung Epithelial ◽  
Sodium Dependent ◽  
Type Ii Cell ◽  
Rate Limiting

Type II lung epithelial cells are different from other lung cell types in their means of processing and regulating intracellular glutathione (GSH) levels. In lung cell types, including endothelial cells, fibroblasts, smooth muscle cells, and macrophages, oxidants, sulfhydryl reagents, and electrophilic agents have been shown to induce cystine uptake and concomitantly increase GSH levels, suggesting that cysteine, formed by intracellular reduction of cystine, is a rate-limiting substrate for GSH synthesis. The cystine transport increase was reportedly due to increase in activity of a sodium-independent transport system designated xc-. We have now examined cultures of rat lung type II cells exposed to diethylmaleic acid and arsenite. Although a rise in cellular GSH occurred, cystine transport was not induced. Cystine transport in type II cells was found to differ from the xc- system previously described. Type II cell cystine transport is primarily sodium dependent and is inhibitable by aspartate as well as glutamate and homocysteate. We conclude that the type II cell differs from other lung cell types in both its cystine transport mechanism and method of GSH regulation.

Glutathione transport by type II cells in perfused rat lung

1994 ◽  
Vol 267 (4) ◽  
pp. L447-L455 ◽  
Author(s):  
C. Bai ◽  
L. A. Brown ◽  
D. P. Jones
Keyword(s):  
Fluorescence Microscopy ◽  
High Performance ◽  
Cell Types ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Uptake System ◽  
Type Ii ◽  
Rat Lung ◽  
Perfused Lung ◽  
Type Ii Cell

Glutathione (GSH) is an antioxidant that protects the lung against oxidative-injury. Most cells rely on synthesis of GSH to maintain intracellular supply and only a few cell types take up intact GSH. Although isolated type II cells from rat have a Na(+)-dependent uptake system that transports GSH into the cells against a concentration gradient, it is not known whether this occurs from the vasculature in the intact lung or whether other cell types in the lung also transport GSH. Based on the knowledge that gamma-glutamyl analogues of GSH are also transported by the Na(+)-GSH transporter, a method was developed and used to study the cell specificity of GSH uptake in perfused lung. A stable, fluorescent GSH S-conjugate (GSH-I14) was synthesized and separated from the original dye as analyzed by high-performance liquid chromatography. Studies with isolated alveolar type II cells showed that uptake of GSH-I14 was Na+ dependent and inhibited by GSH. In addition, uptake of GSH by the type II cells was inhibited by GSH-I14. After perfusion of the isolated rat lung with GSH-I14, the conjugate accumulated primarily in the alveolar type II cell as observed by fluorescence microscopy. This was confirmed by isolation of type II cells and measurement of GSH-I14 content. Thus these results show that specificity of GSH transport can be studied with the fluorescent derivative, GSH-I14, and that in the isolated perfused lung type II cells can transport and concentrate GSH-I14 from the perfusate. Quantitative fluorescence microscopy will be required to further determine relative transport activities by other cell types.

Insulin binding and effects on glucose and transepithelial transport by alveolar type II cells

1984 ◽  
Vol 247 (5) ◽  
pp. C472-C477 ◽  
Author(s):  
K. Sugahara ◽  
G. R. Freidenberg ◽  
R. J. Mason
Keyword(s):  
Glucose Transport ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Cell Types ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Cell Monolayers ◽  
Type Ii Cell

The present experiments were designed to investigate the presence of insulin receptors on isolated adult rat alveolar type II epithelial cells and to study the effect of insulin on glucose transport and ion transport in alveolar type II cell monolayers. Alveolar type II cells in primary culture possess high affinity insulin binding sites, which share biochemical and immunologic similarities with insulin receptors previously identified on other cell types. Competition curves demonstrated half-maximal inhibition of 125I-porcine insulin binding at an unlabeled insulin concentration of 4 ng/ml. Scatchard plots of the binding data were concave upward, as has been reported for insulin binding to other cell types, and were used to calculate that alveolar type II cells contained 17,000 insulin receptor sites per cell. Glucose transport was determined by measurement of initial rates of 2-deoxy-D-glucose uptake. Insulin-stimulated 2-deoxy-D-glucose transport [67.8 +/- 15.7% (mean +/- SE), n = 5, P less than 0.01] with a half-maximally effective insulin concentration of 1.2 +/- 0.6 ng/ml, which is in the physiological range of rat serum insulin concentrations. Insulin effects on the electrical properties of the alveolar type II cell monolayers maintained on collagen-coated Millipore filters were tested in Ussing-type chambers. Insulin increased the potential difference (PD) by 44 +/- 10% (n = 5, P less than 0.01) and short-circuit current (Isc) by 50 +/- 13% (n = 5, P less than 0.01) when it was added to the basolateral side but produced little effect when it was added to the apical side.(ABSTRACT TRUNCATED AT 250 WORDS)

GM-CSF enhances lung growth and causes alveolar type II epithelial cell hyperplasia in transgenic mice

1997 ◽  
Vol 273 (4) ◽  
pp. L715-L725 ◽  
Author(s):  
Jacquelyn A. Huffman Reed ◽  
Ward R. Rice ◽  
Zsuzsanna K. Zsengellér ◽  
Susan E. Wert ◽  
Glenn Dranoff ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Transgenic Mice ◽  
Lung Epithelial Cells ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Cell Hyperplasia ◽  
Α Subunit ◽  
Gm Csf ◽  
Type Ii Cell

The human surfactant protein (SP)-C gene promoter was used to direct expression of mouse granulocyte macrophage colony-stimulating factor (GM-CSF; SP-C-GM mice) in lung epithelial cells in GM-CSF-replete (GM+/+) or GM-CSF null mutant (GM−/−) mice. Lung weight and volume were significantly increased in SP-C-GM mice compared with GM+/+ or GM−/− control mice. Immunohistochemical staining demonstrated marked type II cell hyperplasia, and immunofluorescent labeling for proliferating cell nuclear antigen was increased in type II cells of SP-C-GM mice. Abundance of type II cells per mouse lung was increased three- to fourfold in SP-C-GM mice compared with GM+/+ and GM−/− mice. GM-CSF increased bromodeoxyuridine labeling of isolated type II cells in vitro. Type II cells, alveolar macrophages, and endothelial and bronchiolar epithelial cells were stained by antibodies to the GM-CSF receptor α-subunit in both GM+/+ mice and GM-CSF gene-targeted mice that are also homozygous for the SP-C-GM transgene. High levels of GM-CSF expression in type II cells of transgenic mice increased lung size and caused type II cell hyperplasia, demonstrating an unexpected role for the molecule in the regulation of type II cell proliferation and differentiation.

Transmembrane potential of isolated rat alveolar type II cells

1983 ◽  
Vol 54 (6) ◽  
pp. 1511-1517 ◽  
Author(s):  
V. Castranova ◽  
G. S. Jones ◽  
P. R. Miles
Keyword(s):  
Transmembrane Potential ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Sodium Permeability ◽  
Sodium Dependent ◽  
Type Ii Cell ◽  
Ethanesulfonic Acid

Type II cells were isolated from rat lungs by elastase digestion and purified by centrifugal elutriation. The fluorescent dye, Di-S-C3(5), was used as a probe to monitor transmembrane potential (Em) of cells suspended in N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES)-buffered medium. With this technique, the Em of type II cells was estimated to be -27 +/- 2 mV. This resting Em is very close to the equilibrium potential for chloride (-21 mV), which suggests that chloride is passively distributed in type II cells. The resting Em of type II cells is more dependent on the extracellular concentration of potassium (K+) than on external sodium (Na+); i.e., the membrane depolarizes as external sodium is replaced by potassium, suggesting that in unstimulated type II cells the membrane is more permeable to potassium than to sodium. In addition, the resting potential appears to be due, in part, to the activity of a ouabain-sensitive, Na-K pump, which acts to hyperpolarize type II cells. Addition of a membrane perturbant, phorbol myristate acetate (PMA, 10 micrograms/ml), to a type II cell suspension results in an increase in oxygen consumption and membrane depolarization. Both of these responses are sodium dependent and thus appear to be linked to a PMA-induced increase in sodium permeability.

Sulfation of extracellular matrices modifies responses of alveolar type II cells to fibroblast growth factors

1996 ◽  
Vol 271 (5) ◽  
pp. L688-L697 ◽  
Author(s):  
P. L. Sannes ◽  
J. Khosla ◽  
P. W. Cheng
Keyword(s):  
Growth Factors ◽  
Biological Significance ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Fibroblast Growth ◽  
Alveolar Type Ii Cells ◽  
Proliferation And Differentiation ◽  
Type Ii Cell

The pulmonary alveolar basement membrane (BM) associated with alveolar type II cells has been shown to be significantly less sulfated than that of type I cells. To examine the biological significance of this observation, we measured the incorporation of 5-bromodeoxyuridine (BrdU) as an indicator of DNA synthesis in isolated rat type II cells cultured for 72-120 h on substrata that were naturally sulfated, not sulfated, or chemically desulfated in serum-free, hormonally defined media, with and without selected growth factors. The percentage of cells incorporating BrdU was significantly elevated by desulfated chondroitin sulfate in the presence of fibroblast growth factor-2 (FGF-2 or basic FGF) and depressed by heparin in the presence of either FGF-1 or acidic FGF or FGF-2. This depressive effect was lost by removing sulfate from the heparin. Some responses were dependent on the period of time in culture and concentration and molecular weight of the substrata. These observations support the notion that sulfation per se of certain components of BM is a key determinant of type II cell responses to select growth factors that may define patterns of proliferation and differentiation.

Nitric oxide alters metabolism in isolated alveolar type II cells

1996 ◽  
Vol 271 (1) ◽  
pp. L23-L30 ◽  
Author(s):  
P. R. Miles ◽  
L. Bowman ◽  
L. Huffman
Keyword(s):  
Nitric Oxide ◽  
Oxygen Consumption ◽  
Atp Synthesis ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Atp Content ◽  
Alveolar Type Ii Cells ◽  
Type Ii Cell ◽  
Cellular Oxygen

Alveolar type II cells may be exposed to nitric oxide (.NO) from external sources, and these cells can also generate .NO. Therefore we studied the effects of altering .NO levels on various type II cell metabolic processes. Incubation of cells with the .NO generator, S-nitroso-N-acetylpenicillamine (SNAP; 1 mM), leads to reductions of 60-70% in the synthesis of disaturated phosphatidylcholines (DSPC) and cell ATP levels. Cellular oxygen consumption, an indirect measure of cell ATP synthesis, is also reduced by SNAP. There is no direct effect of SNAP on lung mitochondrial ATP synthesis, suggesting that .NO does not directly inhibit this process. On the other hand, incubation of cells with NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), the enzyme responsible for .NO synthesis, results in increases in DSPC synthesis, cell ATP content, and cellular oxygen consumption. The L-NAME effects are reversed by addition of L-arginine, the substrate for NOS. Production of .NO by type II cells is inhibited by L-NAME, a better inhibitor of constitutive NOS (cNOS) than inducible NOS (iNOS), and is reduced in the absence of external calcium. Aminoguanidine, a specific inhibitor of iNOS, has no effect on cell ATP content or on .NO production. These results indicate that alveolar type II cell lipid and energy metabolism can be affected by .NO and suggest that there may be cNOS activity in these cells.

Enhanced alveolar type II cell growth on a pulmonary extracellular matrix over fibroblasts

1997 ◽  
Vol 272 (3) ◽  
pp. L413-L417 ◽  
Author(s):  
I. Y. Adamson ◽  
L. Young ◽  
J. Bakowska
Keyword(s):  
Extracellular Matrix ◽  
Cell Growth ◽  
Growth Effect ◽  
Lung Fibroblasts ◽  
Cell Contact ◽  
Alveolar Type ◽  
Thymidine Uptake ◽  
Type Ii Cells ◽  
Type Ii ◽  
Type Ii Cell

The growth of alveolar type II cells was studied when these cells were maintained for 2 days on a pulmonary endothelium-derived extracellular matrix (ECM) on a filter with or without lung fibroblasts in the lower chambers of culture wells. Type II cell proliferation was enhanced by the ECM compared with other substrates but was significantly higher with fibroblasts beneath. This was determined by thymidine uptake and cell numbers. The diffusing factor from fibroblasts appeared to be keratinocyte growth factor (KGF), because this cytokine increased type II cell growth in culture and the neutralizing antibody to KGF blocked the observed fibroblast-induced growth increase. None of the antibodies to various cytokines had any effect on the ECM-induced proliferation. Although the type II cells were shown to produce degradative activity for the ECM, there was little secreted enzyme activity in supernatants and there was no demonstrated autocrine-regulated growth effect. The results suggest that type II cell growth may be stimulated by both 1) a matrix-bound factor that acts through a cell contact-mediated process, and 2) a fibroblast-secreted factor that appears to be KGF.

Alveolar type II cell growth on a pulmonary endothelial extracellular matrix

1996 ◽  
Vol 270 (6) ◽  
pp. L1017-L1022 ◽  
Author(s):  
I. Y. Adamson ◽  
L. Young
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Cell Growth ◽  
Alveolar Type ◽  
Thymidine Uptake ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Lamellar Bodies ◽  
Type Ii Cell

Most of the alveolar epithelium overlies a fused basement membrane produced by epithelial and endothelial cells. To determine how this type of matrix influences type II cell growth and function, we studied the effects of culturing isolated rat alveolar type II cells on an extracellular matrix (ECM) freshly produced by pulmonary vascular endothelial cells grown 5 days in culture. Type II cells from the same rats were cultured on plastic or Matrigel for comparison. A large increase in mitotic activity was seen in type II cells grown on the endothelial ECM at 2 days only; thereafter cells spread rapidly to confluence and lost their lamellar bodies. Cells grown on Matrigel remained cuboidal with lamellar bodies but grew more slowly, as judged by [3H]thymidine uptake and cell numbers. Incorporation of labeled choline into disaturated phosphatidylcholine (DSPC) was used as a marker of surfactant synthesis. After the rapid, brief burst of proliferation, type II cells on endothelial ECM showed a sudden decline in DSPC-DNA by day 4 compared with cells grown on matrigel. Binding of the lectin Bauhinia purpurea (BPA) indicated that after a phase of division, cells on endothelial ECM developed as type I epithelium by 4 days of culture, when > 70% of cells stained positively for BPA binding, whereas few cuboidal cells on Matrigel were stained. The results indicate that type II cells respond briefly to growth factors in pulmonary endothelial ECM; then this type of matrix promotes cell spreading with loss of type II function as cells subsequently resemble type I epithelium.

Rat lung type II cell and lamellar body: elemental composition in situ

1988 ◽  
Vol 254 (5) ◽  
pp. C614-C620 ◽  
Author(s):  
R. G. Eckenhoff ◽  
A. P. Somlyo
Keyword(s):  
Elemental Composition ◽  
Lamellar Body ◽  
Cell Types ◽  
Transport Systems ◽  
Alveolar Type ◽  
Type Ii ◽  
Freeze Dried ◽  
Type Ii Cell ◽  
The Difference

We determined the in situ elemental composition of alveolar type II cells (ATII) and lamellar bodies (LB) with electronprobe microanalysis (EPMA) of freeze-dried unstained cryosections (100-200 nm) obtained from lungs frozen in anesthetized rats. Twenty-nine ATII from seven rats were subjected to EPMA. Cytoplasmic (Cyto) composition was the following (in mmol/kg dry wt, mean +/- SE, n = 30): 136 +/- 14.1 Na, 60 +/- 2.8 Mg, 549 +/- 34.8 P, 278 +/- 10.5 S, 158 +/- 7.3 Cl, 525 +/- 26.4 K, and 6.6 +/- 0.9 Ca. LB composition was the following (n = 66): 44 +/- 4.0 Na, 7.9 +/- 0.8 Mg, 1,060 +/- 25.0 P, 79 +/- 4.8 S, 64 +/- 3.6 Cl, 114 +/- 4.1 K, and 30 +/- 0.9 Ca. P and S concentrations were consistent with previous biochemical determinations of phospholipid and protein content of isolated LBs. LBs contain significantly more Ca and less Mg than Cyto. Ca correlated significantly with LB P but not S concentration, and the reported low Ca binding affinity of similar phospholipid mixtures implies a high LB free Ca concentration. Ca was significantly higher in apical and exocytotic LBs compared with those in the perinuclear region. Differences between LB and Cyto monovalent ion concentrations are not entirely due to the difference in hydration revealed by significantly lower K-Cl ratios in LBs. The relative excess of Cl and Ca in LB suggests that these ions may be distributed by active transport systems known to be present in the Golgi apparatus and in Golgi-derived organelles of other cell types.

Sign in / Sign up

Export Citation Format

Share Document