Evaporation-induced changes in airway surface liquid on an isolated guinea pig trachea

1994 ◽  
Vol 76 (3) ◽  
pp. 1156-1165 ◽  
Author(s):  
K. L. Shephard ◽  
H. Rahmoune
Keyword(s):  
Guinea Pig ◽  
Sodium Transport ◽  
Vapor Pressure Deficit ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Airway Surface Liquid ◽  
Sodium Activity ◽  
Surface Liquid ◽  
Induced Changes

An isolated preparation of the guinea pig trachea was developed. The trachea was exposed serosally to Krebs-Henseleit solution and mucosally to tidal airflow, designed to mimic conditions in vivo. The preparation establishes stable layers of airway surface liquid (ASL). Typical depth, transepithelial potential differences, and sodium activity are 200 microns, -3 mV, and 125 mM, respectively (approximate sodium concn 170 mM). When exposed to air with a vapor pressure deficit (VPD), evaporation of water occurs from ASL, ASL depth decreases, and the concentration of sodium ions in ASL increases. The water content of air passing over the trachea also increases. This measurement is compared with measurements of the change in volume of ASL, based on depth changes, to yield estimates of net water transport (NWT). Measurements of changes in the sodium content of ASL allow for the calculation of net sodium transport by the trachea. Evaporation rate, changes in the volume of ASL, NWT, and net sodium transport are all influenced by VPD. The results suggest that evaporation from ASL increases its sodium concentration (and osmotic pressure) and increases osmotically driven NWT to replace water lost. Evaporation-induced increases in the sodium concentration appear to be limited by enhanced sodium uptake at high VPD.

State of airway surface liquid on guinea pig trachea

1995 ◽  
Vol 78 (6) ◽  
pp. 2020-2024 ◽  
Author(s):  
H. Rahmoune ◽  
K. L. Shephard
Keyword(s):  
Relative Humidity ◽  
Guinea Pig ◽  
Osmotic Pressure ◽  
Potential Difference ◽  
Airway Surface Liquid ◽  
Transepithelial Potential Difference ◽  
Air Interface ◽  
Surface Liquid ◽  
Condense Water

Two preparations of the guinea pig trachea have been examined: an isolated preparation and a preparation in vivo, both exposed to air on the mucosal surface. Ion-selective microelectrodes have been used to measure Na (alpha Na) and K activities (alpha K) in airway surface liquid (ASL) while airflows tending either to evaporate or to condense water were applied. Other variables measured included ASL depth and transepithelial potential difference (TEPD). In isolated preparations, condensation did not progressively alter depth, alpha Na, or TEPD but caused a slight increase in alpha K. Evaporation decreased depth; increased alpha Na, alpha K, and osmotic pressure; and changed TEPD. Measurements on preparations in vivo broadly supported these observations. In addition, the depth of ASL developed on isolated preparations was related to the humidity of the air to which animals had been previously exposed. We conclude that condensation and evaporation at the ASL-air interface in isolated preparations and in preparations in vivo do significantly modify key ASL variables as does the relative humidity of the air to which animals are exposed before experimentation.

Airway surface liquid thickness as a function of lung volume in small airways of the guinea pig

1994 ◽  
Vol 77 (5) ◽  
pp. 2333-2340 ◽  
Author(s):  
D. Yager ◽  
T. Cloutier ◽  
H. Feldman ◽  
J. Bastacky ◽  
J. M. Drazen ◽  
...  
Keyword(s):  
Surface Tension ◽  
Epithelial Cells ◽  
Guinea Pig ◽  
Cross Sections ◽  
Lung Volume ◽  
Longitudinal Direction ◽  
Small Airways ◽  
Airway Surface Liquid ◽  
Residual Capacity ◽  
Surface Liquid

The average thickness and distribution of airway surface liquid (ASL) on the luminal surface of peripheral airways were measured in normal guinea pig lungs frozen at functional residual capacity (FRC) and total lung capacity (TLC). Tissue blocks containing cross sections of airways of internal perimeter 0.188–3.342 mm were cut from frozen lungs and imaged by low-temperature scanning electron microscopy (LTSEM). Measurements made from LTSEM images were found to be independent of freezing rate by comparison of measurements at rapid and slow freezing rates. At both lung volumes, the ASL was not uniformly distributed in either the circumferential or longitudinal direction; there were regions of ASL where its thickness was < 0.1 micron, whereas in other regions ASL collected in pools. Discernible liquid on the surfaces of airways frozen at FRC followed the contours of epithelial cells and collected in pockets formed by neighboring cells, a geometry consistent with a low value of surface tension at the air-liquid interface. At TLC airway liquid collected to cover epithelial cells and to form a liquid meniscus, a geometry consistent with a higher value of surface tension. The average ASL thickness (h) was approximately proportional to the square root of airway internal perimeter, regardless of lung volume. For airways of internal perimeter 250 and 1,800 microns, h was 0.9 and 1.8 microns at FRC and 1.7 and 3.7 microns at TLC, respectively. For a given airway internal perimeter, h was 1.99 times thicker at TLC than at FRC; the difference was statistically significant (P < 0.01; 95% confidence interval 1.29–3.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation of the Extracellular [Bicarbonate]/[Chloride] Ratio to Erythrocyte Sodium Content: A Possible New Control System

1972 ◽  
Vol 43 (3) ◽  
pp. 311-318 ◽  
Author(s):  
M. A. Needle ◽  
W. Shapiro ◽  
V. Viswanathan ◽  
M. Semar
Keyword(s):  
Control System ◽  
Membrane Permeability ◽  
Ethacrynic Acid ◽  
Sodium Concentration ◽  
Sodium Content ◽  
Atp Depletion ◽  
Carrier System ◽  
Erythrocyte Sodium ◽  
Induced Changes

1. Erythrocytes were incubated in buffers with different [bicarbonate]/[chloride] ratios. 2. The erythrocyte sodium content was higher in buffers with higher [bicarbonate]/ [chloride] ratios. 3. The rise in erythrocyte sodium concentration with increase in [bicarbonate]/[chloride] ratio was independent of the effects of ouabain and ouabain plus ethacrynic acid. Primaquine-induced changes in membrane permeability, ATP depletion by starvation and the use of potassium-free buffers did not change the effect. 4. The results may demonstrate a system which either increases the permeability of erythrocytes to sodium or regulates the sodium content of erythrocytes by a carrier system which is independent of ATP.

Regulation of Airway Surface Liquid on the Isolated Guinea-pig Trachea

1994 ◽  
Vol 7 (4) ◽  
pp. 265-269 ◽  
Author(s):  
H. Rahmoune ◽  
K.L. Shephard
Keyword(s):  
Guinea Pig ◽  
Airway Surface Liquid ◽  
Surface Liquid

Effects of spironolactone and amiloride on corticosteroid-induced changes in colonic function

1981 ◽  
Vol 241 (4) ◽  
pp. G300-G305
Author(s):  
A. N. Charney ◽  
J. Wallach ◽  
S. Ceccarelli ◽  
M. Donowitz ◽  
C. L. Costenbader
Keyword(s):  
Atpase Activity ◽  
Water Absorption ◽  
Sodium Transport ◽  
Transport Processes ◽  
Potential Difference ◽  
Pentobarbital Sodium ◽  
Electrolyte Absorption ◽  
Potassium Secretion ◽  
Induced Changes

Mineralocorticoid and glucocorticoid effects on colonic electrolyte absorption were compared by examining the alterations caused by spironolactone and amiloride in corticosteroid-treated rats. Animals were treated for 3 days with deoxycorticosterone acetate (DOCA; 0.5 mg . 100 g-1 . day-1), methylprednisolone (MP; 3 or 0.5 mg . 100 g-1 . day), and spironolactone (14 mg . 100 g-1 . day-1 im) singly or in combination. On day 4, rats were anesthetized with pentobarbital sodium and perfused in vivo with Ringer-HCO3 solution. Both doses of MP and DOCA increased net colonic sodium and water absorption and mucosal Na-K-ATPase activity. Concurrent spironolactone treatment completely prevented these effects in DOCA-treated rats but had no effect in MP-treated rats. Untreated, MP-treated, and DOCA-treated animals were perfused with a Ringer-HCO3 solution containing 1 mM amiloride. Amiloride reduced net colonic sodium and water absorption, transmural potential difference, and potassium secretion in all rats by approximately 55%. These effects were almost immediate and completely reversible. These findings in the rat suggest that 1) different receptors mediate the colonic effects of mineralocorticoids and glucocorticoids and 2) these corticosteroids do not differ in their relative effects on amiloride-sensitive and amiloride-resistant colonic sodium transport processes.

scholarly journals Engineered mutant α-ENaC subunit mRNA delivered by lipid nanoparticles reduces amiloride currents in cystic fibrosis–based cell and mice models

2020 ◽  
Vol 6 (47) ◽  
pp. eabc5911
Author(s):  
Anindit Mukherjee ◽  
Kelvin D. MacDonald ◽  
Jeonghwan Kim ◽  
Michael I. Henderson ◽  
Yulia Eygeris ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Therapeutic Potential ◽  
Lipid Nanoparticles ◽  
Sodium Absorption ◽  
Airway Surface Liquid ◽  
Surface Liquid ◽  
Cf Transmembrane Conductance Regulator ◽  
Airway Cells

Cystic fibrosis (CF) results from mutations in the chloride-conducting CF transmembrane conductance regulator (CFTR) gene. Airway dehydration and impaired mucociliary clearance in CF is proposed to result in tonic epithelial sodium channel (ENaC) activity, which drives amiloride-sensitive electrogenic sodium absorption. Decreasing sodium absorption by inhibiting ENaC can reverse airway surface liquid dehydration. Here, we inhibit endogenous heterotrimeric ENaC channels by introducing inactivating mutant ENaC α mRNA (αmutENaC). Lipid nanoparticles carrying αmutENaC were transfected in CF-based airway cells in vitro and in vivo. We observed a significant decrease in macroscopic as well as amiloride-sensitive ENaC currents and an increase in airway surface liquid height in CF airway cells. Similarly, intranasal transfection of αmutENaC mRNA decreased amiloride-sensitive nasal potential difference in CFTRKO mice. These data suggest that mRNA-based ENaC inhibition is a powerful strategy for reducing mucus dehydration and has therapeutic potential for treating CF in all patients, independent of genotype.

Effects of vasopressin and aldosterone on amiloride binding in toad bladder epithelial cells

1975 ◽  
Vol 189 (1097) ◽  
pp. 543-575 ◽  
Keyword(s):  
Epithelial Cells ◽  
Sodium Transport ◽  
Binding Sites ◽  
Specific Binding ◽  
Sodium Concentration ◽  
Isolated Cells ◽  
The Right ◽  
Transepithelial Sodium Transport

Methods have been devised to measure the binding of [ 14 C]amiloride to isolated cells from bladders of toads, Bufo marinus . This agent blocks transepithelial sodium transport across bladders by preventing sodium entry to the transporting mechanism. A saturable binding component has been found with an affinity of 5.6 x 10 7 m -1 in the presence of 1.1 mM Na + , which corresponds to the affinity of amiloride when used as a transport inhibitor at the same sodium concentration. In freshly isolated cells the capacity of the binding sites is 3.6 x 10 5 sites/cell, but this value falls to about one third in aged suspensions. When cells are treated with vasopressin (100 mU/ml) somewhat less specific binding is measured at an amiloride concentration giving 50 % occupancy. The results are consistent with the view that vasopressin moves the binding curve to the right along the concentration axis, reducing the affinity of amiloride by a factor of approximately two, while leaving the total capacity unaffected. The affinity of amiloride when used as an inhibitor of transport is also found to be reduced by a factor of two by vasopressin, and complete inhibition of transport can still be achieved. d -Aldosterone in vitro increases the number of amiloride binding sites in isolated cells by approximately 115%, and results from transport studies indicate that there is no significant change in the affinity of amiloride after d -aldosterone treatment. Inhibitors of transcription and translation (actinomycin D and cycloheximide) prevent the increase in amiloride binding caused by d -aldosterone. In vivo the effects of d -aldosterone are more complex, but it is shown that the steroid increases the transport capacity of the tissue, when this is expressed as the number of amiloride binding sites per unit mass of tissue. The results are discussed in terms of the ways in which the two hormones may alter the entry of sodium into the epithelial cells, and so in turn affect transepithelial sodium transport.

scholarly journals Culture with apically applied healthy or disease sputum alters the airway surface liquid proteome and ion transport across human bronchial epithelial cells.

2021 ◽  
Author(s):  
Maximillian Woodall ◽  
Boris Reidel ◽  
Mehmet Kesimer ◽  
Robert Tarran ◽  
Deborah L Baines
Keyword(s):  
Epithelial Cells ◽  
Ion Transport ◽  
Short Circuit ◽  
Bronchial Epithelial Cells ◽  
Airway Surface Liquid ◽  
Human Bronchial Epithelial Cells ◽  
Bronchial Epithelial ◽  
Surface Liquid

Airway secretions contain many signalling molecules and peptides/proteins that are not found in airway surface liquid (ASL) generated by normal human bronchial epithelial cells (NHBE) in vitro. These play a key role in innate defence and mediate communication between the epithelium, immune cells and the external environment. We investigated how culture of NHBE with apically applied secretions from healthy or disease (Cystic Fibrosis, CF) lungs affected epithelial function with a view to providing better in vitro models of the in vivo environment. NHBE from 6-8 different donors were cultured at air-liquid interface (ALI), with apically applied sputum from normal healthy donors (NLS) or CF donors (CFS) for 2-4 hours, 48 hours or with sputum reapplied over 48 hours. Proteomic analysis was carried out on the sputa and on NHBE ASL before and after culture with sputa. Transepithelial electrical resistance (TEER), short circuit current (Isc) and changes to ASL height were measured. There were 71 proteins common to both sputa but not ASL. The protease:protease inhibitor balance was increased in CFS compared to NLS and ASL. Culture of NHBE with sputa for 48 hours identified additional factors not present in NLS, CFS or ASL alone. Culture with either NLS or CFS for 48 hours increased CFTR activity, calcium activated chloride channel (CaCC) activity and changed ASL height. These data indicate that culture with healthy or disease sputum changes the proteomic profile of ASL and ion transport properties of NHBE and this may increase physiological relevance when using in vitro airway models.

Technical Approaches to Analyze the In Vivo Ion Composition of Airway Surface Liquid

2003 ◽  
pp. 563-572
Author(s):  
Jean-Marie Zahm ◽  
Sonia Baconnais ◽  
Gérard Balossier ◽  
Edith Puchelle
Keyword(s):  
Airway Surface Liquid ◽  
Ion Composition ◽  
Surface Liquid

scholarly journals Determination of rheology and surface tension of airway surface liquid: a review of clinical relevance and measurement techniques

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhenglong Chen ◽  
Ming Zhong ◽  
Yuzhou Luo ◽  
Linhong Deng ◽  
Zhaoyan Hu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Clinical Relevance ◽  
Measurement Techniques ◽  
Barrier Properties ◽  
Airway Surface Liquid ◽  
Surfactant Replacement Therapy ◽  
Surface Liquid ◽  
The Stability

AbstractBy airway surface liquid, we mean a thin fluid continuum consisting of the airway lining layer and the alveolar lining layer, which not only serves as a protective barrier against foreign particles but also contributes to maintaining normal respiratory mechanics. In recent years, measurements of the rheological properties of airway surface liquid have attracted considerable clinical attention due to new advances in microrheology instruments and methods. This article reviews the clinical relevance of measurements of airway surface liquid viscoelasticity and surface tension from four main aspects: maintaining the stability of the airways and alveoli, preventing ventilator-induced lung injury, optimizing surfactant replacement therapy for respiratory syndrome distress, and characterizing the barrier properties of airway mucus to improve drug and gene delivery. Primary measuring techniques and methods suitable for determining the viscoelasticity and surface tension of airway surface liquid are then introduced with respect to principles, advantages and limitations. Cone and plate viscometers and particle tracking microrheometers are the most commonly used instruments for measuring the bulk viscosity and microviscosity of airway surface liquid, respectively, and pendant drop methods are particularly suitable for the measurement of airway surface liquid surface tension in vitro. Currently, in vivo and in situ measurements of the viscoelasticity and surface tension of the airway surface liquid in humans still presents many challenges.

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