Ascorbate uptake by isolated rat alveolar macrophages and type II cells

1983 ◽  
Vol 54 (1) ◽  
pp. 208-214 ◽  
Author(s):  
V. Castranova ◽  
J. R. Wright ◽  
H. D. Colby ◽  
P. R. Miles
Keyword(s):  
Alveolar Macrophages ◽  
Membrane Surface ◽  
Lung Cells ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Sodium Influx ◽  
Saturation Kinetics ◽  
Ascorbate Uptake ◽  
Isolated Rat

Studies were conducted to measure intracellular ascorbate content and to characterize ascorbate uptake in three fractions of isolated rat pneumocytes (i.e., alveolar macrophages, alveolar type II epithelial cells, and another fraction of small pneumocytes that contains neither macrophages nor type II cells). When cells are incubated in medium containing 0.1 mM ascorbate (i.e., the concentration normally found in plasma), intracellular ascorbate concentrations are 3.2 mM in alveolar macrophages and type II cells and 0.9 mM in other lung cells; ascorbate influx is 1.5 nmol . 10(7) cells-1 . h-1 for alveolar macrophages, 0.24 nmol . 10(7) cells-1 . h-1 for type II cells, and very slow in other pneumocytes. Ascorbate influx displays saturation kinetics in both alveolar macrophages (K1/2 = 2 mM; Vmax = 32.2 nmol . 10(7) cells-1 . h-1) and type II cells (K1/2 = 5 mM; Vmax = 14.2 nmol . 10(7) cells-1 . h-1). After correction for differences in the membrane surface areas of these two types of lung cells, the rates for maximum ascorbate influx (Vmax) are similar in alveolar macrophages and type II cells. In addition, ascorbate uptake by alveolar macrophages and type II cells is dependent on metabolic activity and extracellular sodium. In contrast, ascorbate uptake in other lung cells does not exhibit saturation kinetics and is not dependent on metabolism or sodium. Thus alveolar macrophages and type II cells possess an energy-dependent cotransport system for ascorbate and sodium influx. The high ascorbate content and the existence of a specialized transport mechanism for ascorbate uptake may explain the relative resistance of alveolar macrophages and type II cells to oxidant injury.

Influence of phosphatidylglycerol on the uptake of liposomes by alveolar cells and on lung function

2005 ◽  
Vol 98 (5) ◽  
pp. 1784-1791 ◽  
Author(s):  
D. L. H. Poelma ◽  
B. Lachmann ◽  
J. J. Haitsma ◽  
L. J. Zimmermann ◽  
J. F. van Iwaarden
Keyword(s):  
Lung Function ◽  
Alveolar Macrophages ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Negative Effects ◽  
Alveolar Cells ◽  
Alveolar Type Ii Cells ◽  
High Concentrations

The effect of phosphatidylglycerol on the uptake of surfactant-like liposomes by alveolar type II cells and alveolar macrophages as well as the effect on endogenous surfactant function was studied in vivo. Healthy ventilated rats were intratracheally instilled with fluorescent labeled liposomes with different concentrations of phosphatidylglycerol. Lung function was determined by monitoring arterial oxygenation and, at the end of the experiment, by recording static pressure-volume curves. In addition, alveolar cells were isolated, and cell-associated fluorescence was determined using flow cytometry. The results show that, in the presence of cofactors (Ca2+, Mg2+), phosphatidylglycerol stimulates the uptake by alveolar macrophages but hardly affects the uptake by alveolar type II cells. High concentrations of phosphatidylglycerol reduce the number of alveolar macrophages in the alveolar space and deteriorate lung function. On the other hand, the presence of cofactors protects the lung against the negative effects of phosphatidylglycerol on endogenous surfactant and alveolar macrophages. This study indicates that the phosphatidylglycerol concentration may play a fundamental role in the surfactant function and metabolism depending on the presence of so-called cofactors like calcium and magnesium; further study is needed to clarify the mechanisms involved.

Toxicity of metallic ions in the lung: Effects on alveolar macrophages and alveolar type II cells

1984 ◽  
Vol 13 (4-6) ◽  
pp. 845-856 ◽  
Author(s):  
Vincent Castranova ◽  
Linda Bowman ◽  
Jo Rae Wright ◽  
Howard Colby ◽  
Philip R. Miles
Keyword(s):  
Alveolar Macrophages ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Metallic Ions ◽  
Alveolar Type Ii Cells

scholarly journals Phospholipid-transfer activities in cytosols from lung, isolated alveolar type II cells and alveolar type II cell-derived adenomas

1983 ◽  
Vol 215 (3) ◽  
pp. 637-642 ◽  
Author(s):  
G L Pool ◽  
D G Bubacz ◽  
R H Lumb ◽  
R J Mason
Keyword(s):  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Transfer Protein ◽  
Alveolar Type Ii Cell ◽  
Phospholipid Transfer ◽  
Type Ii Cell ◽  
Specific Proteins ◽  
Isolated Rat

We have examined phospholipid-transfer activities in cytosols from rat and mouse whole lung, isolated rat alveolar type II cells and alveolar type II cell-derived mouse pulmonary adenomas. We report an enrichment in phosphatidylcholine and phosphatidylglycerol (but not phosphatidylinositol) protein-catalysed transfer in the type II cell and adenoma cytosols compared with the whole-lung cytosols. The activities from these cytosols were resolved using column chromatofocusing, which clearly demonstrated the presence of a phosphatidylcholine-specific transfer protein in each of the four tissues. In addition, two proteins (rat) or three proteins (mouse) catalysing both phosphatidylcholine and phosphatidylglycerol transfer were resolved from whole lung, whereas in both the rat isolated alveolar type II cells and the mouse type II cell-derived adenomas one of these less specific proteins is not present.

Distinct effects of SP-B and SP-C on the uptake of surfactant-like liposomes by alveolar cells in vivo and in vitro

2004 ◽  
Vol 287 (5) ◽  
pp. L1056-L1065 ◽  
Author(s):  
D. L. H. Poelma ◽  
L. J. Zimmermann ◽  
W. A. van Cappellen ◽  
J. J. Haitsma ◽  
B. Lachmann ◽  
...  
Keyword(s):  
Alveolar Macrophages ◽  
Divalent Cations ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Cells ◽  
Alveolar Type Ii Cells ◽  
Lipid Ratio

The effects of surfactant protein B (SP-B) and SP-C on the uptake of surfactant-like liposomes by alveolar type II cells and alveolar macrophages were studied both in vivo and in vitro. In vivo, mechanically ventilated rats were intratracheally instilled with fluorescently labeled liposomes that had SP-B and/or SP-C incorporated in different concentrations. Consequently, the alveolar cells were isolated, and cell-associated fluorescence was determined using flow cytometry. The results show that the incorporation of SP-B does not influence the uptake, and it also does not in the presence of essential cofactors. The inclusion of SP-C in the liposomes enhanced the alveolar type II cells at a SP-C to lipid ratio of 2:100. If divalent cations (calcium and magnesium) were present at physiological concentrations in the liposome suspension, uptake of liposomes by alveolar macrophages was also enhanced. In vitro, the incorporation of SP-B affected uptake only at a protein-to-lipid ratio of 8:100, whereas the inclusion of SP-C in the liposomes leads to an increased uptake at a protein-to-lipid ratio of 1:100. From these results, it can be concluded that SP-B is unlikely to affect uptake of surfactant, whereas SP-C in combination with divalent cations and other solutes are capable of increasing the uptake.

In vivo and in vitro uptake of surfactant lipids by alveolar type II cells and macrophages

2002 ◽  
Vol 283 (3) ◽  
pp. L648-L654 ◽  
Author(s):  
D. L. H. Poelma ◽  
L. J. I. Zimmermann ◽  
H. H. Scholten ◽  
B. Lachmann ◽  
J. F. van Iwaarden
Keyword(s):  
Alveolar Macrophages ◽  
Alveolar Type ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Cells ◽  
Alveolar Type Ii Cells ◽  
Small Subpopulation

The uptake of fluorescent-labeled liposomes (with a surfactant-like composition) by alveolar macrophages and alveolar type II cells was studied using flow cytometry, in vivo by instillation of the labeled liposomes in the trachea of ventilated rats followed by isolation of the alveolar cells and determination of the cell-associated fluorescence, and in vitro by incubation of isolated alveolar cells with the fluorescent liposomes. The results show that the uptake of liposomes by the alveolar cells is time and concentration dependent. In vivo alveolar macrophages internalize more than three times as many liposomes as alveolar type II cells, whereas in vitro, the amount of internalized liposomes by these cells is approximately the same. In vitro, practically all the cells (70–75%) internalize liposomes, whereas in vivo only 30% of the alveolar type II cells ingest liposomes vs. 70% of the alveolar macrophages. These results indicate that in vivo, only a small subpopulation of alveolar type II cells is able to internalize surfactant liposomes.

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