Dynamin-dependent Trafficking Of Polystyrene Nanoparticles Across Madin Darby Canine Kidney But Not Rat Alveolar Epithelial Cell Monolayers

Primary rat alveolar epithelial cell monolayers (RAECM) were grown without (type I cell-like phenotype, RAECM-I) or with (type II cell-like phenotype, RAECM-II) keratinocyte growth factor to assess passive transport of 11 hydrophilic solutes. We estimated apparent permeability (Papp) in the absence/presence of calcium chelator EGTA to determine the effects of perturbing tight junctions on “equivalent” pores. Papp across RAECM-I and -II in the absence of EGTA are similar and decrease as solute size increases. We modeled Papp of the hydrophilic solutes across RAECM-I/-II as taking place via heterogeneous populations of equivalent pores comprised of small (0.41/0.32 nm radius) and large (9.88/11.56 nm radius) pores, respectively. Total equivalent pore area is dominated by small equivalent pores (99.92–99.97%). The number of small and large equivalent pores in RAECM-I was 8.55 and 1.29 times greater, respectively, than those in RAECM-II. With EGTA, the large pore radius in RAECM-I/-II increased by 1.58/4.34 times and the small equivalent pore radius increased by 1.84/1.90 times, respectively. These results indicate that passive diffusion of hydrophilic solutes across an alveolar epithelium occurs via small and large equivalent pores, reflecting interactions of transmembrane proteins expressed in intercellular tight junctions of alveolar epithelial cells.

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Mechanisms of liquid flux across pulmonary alveolar epithelial cell monolayers

In Vitro Cellular & Developmental Biology - Animal ◽

10.1007/s11626-997-0141-z ◽

1997 ◽

Vol 33 (3) ◽

pp. 195-200 ◽

Cited By ~ 16

Author(s):

Gerasimos S. Filippatos ◽

W. Frank Hughes ◽

Renli Qiao ◽

J. Iasha Sznajder ◽

Bruce D. Uhal

Keyword(s):

Epithelial Cell ◽

Alveolar Epithelial Cell ◽

Cell Monolayers ◽

Alveolar Epithelial ◽

Liquid Flux ◽

Epithelial Cell Monolayers

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Modulation of ion conductance and active transport by TGF-β1 in alveolar epithelial cell monolayers

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00379.2002 ◽

2003 ◽

Vol 285 (6) ◽

pp. L1192-L1200 ◽

Cited By ~ 20

Author(s):

Brigham C. Willis ◽

Kwang-Jin Kim ◽

Xian Li ◽

Janice Liebler ◽

Edward D. Crandall ◽

...

Keyword(s):

Epithelial Cell ◽

Active Transport ◽

Alveolar Epithelial Cell ◽

Alveolar Type ◽

Type I ◽

Ion Conductance ◽

Cell Monolayers ◽

Alveolar Epithelial ◽

Epithelial Cell Monolayers ◽

Tgf Β1

Transforming growth factor-β1 (TGF-β1) may be a critical mediator of lung injury and subsequent remodeling during recovery. We evaluated the effects of TGF-β1 on the permeability and active ion transport properties of alveolar epithelial cell monolayers. Rat alveolar type II cells plated on polycarbonate filters in defined serum-free medium form confluent monolayers and acquire the phenotypic characteristics of alveolar type I cells. Exposure to TGF-β1 (0.1-100 pM) from day 0 resulted in a concentration- and time-dependent decrease in transepithelial resistance ( Rt) and increase in short-circuit current ( Isc). Apical amiloride or basolateral ouabain on day 6 inhibited Isc by 80 and 100%, respectively. Concurrent increases in expression of Na+-K+-ATPase α1- and β1-subunits were observed in TGF-β1-treated monolayers. No change in the α-subunit of the rat epithelial sodium channel (α-rENaC) was seen. Exposure of confluent monolayers to TGF-β1 from day 4 resulted in an initial decrease in Rt within 6 h, followed by an increase in Isc over 72-96 h. These results demonstrate that TGF-β1 modulates ion conductance and active transport characteristics of the alveolar epithelium, associated with increased Na+-K+-ATPase, but without a change in α-rENaC.

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Rates of Protein Transport Across Rat Alveolar Epithelial Cell Monolayers

Journal of Drug Targeting ◽

10.3109/10611869909085516 ◽

1999 ◽

Vol 7 (5) ◽

pp. 335-342 ◽

Cited By ~ 30

Author(s):

Yasuhisa Matsukawa ◽

Hiroshi Yamahara ◽

Fumiyoshi Yamashita ◽

Vincent H.L. Lee ◽

Edward D. Crandall ◽

...

Keyword(s):

Epithelial Cell ◽

Protein Transport ◽

Alveolar Epithelial Cell ◽

Cell Monolayers ◽

Alveolar Epithelial ◽

Epithelial Cell Monolayers

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Regulation of transport across pulmonary alveolar epithelial cell monolayers

Journal of Applied Physiology ◽

10.1152/jappl.1984.57.3.703 ◽

1984 ◽

Vol 57 (3) ◽

pp. 703-710 ◽

Cited By ~ 51

Author(s):

B. E. Goodman ◽

S. E. Brown ◽

E. D. Crandall

Keyword(s):

Epithelial Cell ◽

Alveolar Epithelial Cell ◽

Phosphodiesterase Inhibitors ◽

Beta Agonist ◽

Type Ii ◽

Dome Formation ◽

Cell Monolayers ◽

Cyclic Monophosphate ◽

Alveolar Epithelial ◽

Epithelial Cell Monolayers

Domes are formed in large numbers by primary cultured monolayers of type II alveolar epithelial cells from rat lungs. These fluid-filled structures are formed by active transport of solute from medium to substratum, with water following passively. In the present study, we used dome-forming monolayers to study the regulation of alveolar epithelial transport processes by determining the effects on dome formation of adenosine 3',5'-cyclic monophosphate (cAMP) analogues, phosphodiesterase inhibitors, neurotransmitters, and vasopressin (antidiuretic hormone, ADH). The cAMP analogues (dibutyryl cAMP and 8-bromo-cAMP) and phosphodiesterase inhibitors (theophylline, papaverine, and isobutylmethylxanthine) caused large increases in dome formation by 24 h. ADH and beta-adrenergic agonists (epinephrine, terbutaline, and isoproterenol) also caused significant increases in dome density. The beta-agonist response was completely eliminated in the presence of the beta-blocker propranolol. Dibutyryl guanosine 3',5'-cyclic monophosphate and acetylcholine (cholinergic agonist) had no effect on dome formation, whereas the alpha-adrenergic agonist methoxamine caused a small but significant decrease in dome formation. These findings suggest that the active solute flux resulting in dome formation by type II alveolar epithelial cell monolayers is increased by substances expected to elevate intracellular cAMP (or analogue) concentrations. An attractive speculation having major implications for lung fluid balance is that transepithelial fluxes can be modulated by endogenous, and perhaps exogenous, chemical agents in adult mammalian alveolar epithelium in vivo.

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Effect of stretch on structural integrity and micromechanics of human alveolar epithelial cell monolayers exposed to thrombin

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00436.2005 ◽

2006 ◽

Vol 290 (6) ◽

pp. L1104-L1110 ◽

Cited By ~ 19

Author(s):

Xavier Trepat ◽

Ferranda Puig ◽

Nuria Gavara ◽

Jeffrey J. Fredberg ◽

Ramon Farre ◽

...

Keyword(s):

Mechanical Ventilation ◽

Epithelial Cell ◽

Structural Integrity ◽

Alveolar Epithelial Cell ◽

Compressive Strain ◽

Cell Junctions ◽

Cell Monolayers ◽

Alveolar Epithelial ◽

Epithelial Cell Monolayers ◽

Human Alveolar Epithelial Cell

Alveolar epithelial cells in patients with acute lung injury subjected to mechanical ventilation are exposed to increased procoagulant activity and mechanical strain. Thrombin induces epithelial cell stiffening, contraction, and cytoskeletal remodeling, potentially compromising the balance of forces at the alveolar epithelium during cell stretching. This balance can be further compromised by the loss of integrity of cell-cell junctions in the injured epithelium. The aim of this work was to study the effect of stretch on the structural integrity and micromechanics of human alveolar epithelial cell monolayers exposed to thrombin. Confluent and subconfluent cells (A549) were cultured on collagen-coated elastic substrates. After exposure to thrombin (0.5 U/ml), a stepwise cell stretch (20%) was applied with a vacuum-driven system mounted on an inverted microscope. The structural integrity of the cell monolayers was assessed by comparing intercellular and intracellular strains within the monolayer. Strain was measured by tracking beads tightly bound to the cell surface. Simultaneously, cell viscoelasticity was measured using optical magnetic twisting cytometry. In confluent cells, thrombin did not induce significant changes in transmission of strain from the substrate to overlying cells. By contrast, thrombin dramatically impaired the ability of subconfluent cells to follow imposed substrate deformation. Upon substrate unstretching, thrombin-treated subconfluent cells exhibited compressive strain (9%). Stretch increased stiffness (56–62%) and decreased cell hysteresivity (13–22%) of vehicle cells. By contrast, stretch did not increase stiffness of thrombin-treated cells, suggesting disruption of cytoskeletal structures. Our findings suggest that thrombin could exacerbate epithelial barrier dysfunction in injured lungs subjected to mechanical ventilation.

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