Control of pH of airway surface liquid of the ferret trachea in vitro

1990 ◽  
Vol 68 (1) ◽  
pp. 135-140 ◽  
Author(s):  
H. Kyle ◽  
J. P. Ward ◽  
J. G. Widdicombe
Keyword(s):  
Interstitial Fluid ◽  
Ex Situ ◽  
Co2 Production ◽  
Limiting Factor ◽  
Organ Bath ◽  
Airway Surface Liquid ◽  
Tracheal Lumen ◽  
Surface Liquid ◽  
External Ph

We measured the pH of airway surface liquid (ASL) secreted by the ferret trachea in vitro by using a catheter-tipped pH electrode implanted in a collecting cannula close to the airway epithelium. Mucus secretion was promoted by methacholine (0.02 mmol/l) in the organ bath. The pH of the ASL was 6.85 +/- 0.03 (SE) compared with a bath value of 7.39 +/- 0.01, when the bath was bubbled with 5.65% CO2. Changing the bath CO2 from 0 to 20.93% CO2 altered the bath pH from 8.06 to 6.96, but the ASL pH only varied from 6.92 to 6.85. This homeostasis of ASL pH was not the result of the buffering powers of the ASL, because ex situ buffer curves for secreted ASL were similar to those for Krebs-Henseleit solution. Changing the luminal CO2 content by blowing gases through the trachea changed ASL pH by values similar to that ex situ. However, when external organ bath CO2 was changed, the luminal CO2 changes were proportionately far smaller. Measurement of rates of diffusion of CO2 across the tracheal wall indicated that this was not a limiting factor in the results. Similarly, measurement of metabolic rate CO2 production in the tracheal lumen indicated that this did not significantly affect the results. We conclude that the pH of ASL is significantly on the acid side of the pH or interstitial fluid and plasma and that it is maintained relatively constant despite large changes in external pH.

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.

In Vitro Aerosol Delivery and Regional Airway Surface Liquid Concentration of a Liposomal Cationic Peptide

2001 ◽  
Vol 90 (10) ◽  
pp. 1647-1657 ◽  
Author(s):  
Carlos F. Lange ◽  
Robert E.W. Hancock ◽  
John Samuel ◽  
Warren H. Finlay
Keyword(s):  
Airway Surface Liquid ◽  
Cationic Peptide ◽  
Aerosol Delivery ◽  
Liquid Concentration ◽  
Surface Liquid

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.

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.

scholarly journals In Vivo Airway Surface Liquid Cl− Analysis with Solid-State Electrodes

2001 ◽  
Vol 119 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Ray A. Caldwell ◽  
Barbara R. Grubb ◽  
Robert Tarran ◽  
Richard C. Boucher ◽  
Michael R. Knowles ◽  
...  
Keyword(s):  
Solid State ◽  
Airway Surface Liquid ◽  
Culture Models ◽  
Normal Human ◽  
Surface Liquid ◽  
Multiple Species ◽  
Cell Culture Models ◽  
Made In

The pathogenesis of cystic fibrosis (CF) airways disease remains controversial. Hypotheses that link mutations in CFTR and defects in ion transport to CF lung disease predict that alterations in airway surface liquid (ASL) isotonic volume, or ion composition, are critically important. ASL [Cl−] is pivotal in discriminating between these hypotheses, but there is no consensus on this value given the difficulty in measuring [Cl−] in the “thin” ASL (∼30 μm) in vivo. Consequently, a miniaturized solid-state electrode with a shallow depth of immersion was constructed to measure ASL [Cl−] in vivo. In initial experiments, the electrode measured [Cl−] in physiologic salt solutions, small volume (7.6 μl) test solutions, and in in vitro cell culture models, with ≥93% accuracy. Based on discrepancies in reported values and/or absence of data, ASL Cl− measurements were made in the following airway regions and species. First, ASL [Cl−] was measured in normal human nasal cavity and averaged 117.3 ± 11.2 mM (n = 6). Second, ASL [Cl−] measured in large airway (tracheobronchial) regions were as follows: rabbit trachea and bronchus = 114.3 ± 1.8 mM; (n = 6) and 126.9 ± 1.7 mM; (n = 3), respectively; mouse trachea = 112.8 ± 4.2 mM (n = 13); and monkey bronchus = 112.3 ± 10.9 mM (n = 3). Third, Cl− measurements were made in small (1–2 mm) diameter airways of the rabbit (108.3 ± 7.1 mM, n = 5) and monkey (128.5 ± 6.8 mM, n = 3). The measured [Cl−], in excess of 100 mM throughout all airway regions tested in multiple species, is consistent with the isotonic volume hypothesis to describe ASL physiology.

scholarly journals Estimation of thickness of airway surface liquid in ferret trachea in vitro

1997 ◽  
Vol 83 (3) ◽  
pp. 761-767 ◽  
Author(s):  
S. Duneclift ◽  
U. Wells ◽  
J. Widdicombe
Keyword(s):  
Permeability Coefficient ◽  
Airway Surface Liquid ◽  
Diethylenetriaminepentaacetic Acid ◽  
Mean Values ◽  
Initial Concentration ◽  
Initial Volume ◽  
Surface Liquid

Duneclift, S., U. Wells, and J. Widdicombe. Estimation of thickness of airway surface liquid in ferret trachea in vitro. J. Appl. Physiol. 83(3): 761–767, 1997.—The tracheae of ferrets and rabbits were mounted in vitro in organ baths. While the tracheae were liquid filled, the permeability coefficient ( P) was determined, and then while the tracheae were air filled, the percent clearance for99mTc-labeled diethylenetriaminepentaacetic acid (DTPA) was determined. The thickness of airway surface liquid (ASL) was estimated by three methods. 1) The initial concentration of99mTc-DTPA and the total amount of99mTc-DTPA (the sum of that entering the outside medium, that draining from the trachea, and that washed out at the end of 40 min) gave the initial volume of ASL and thus its thickness. Mean values were 45.7 μm for the ferret and 41.9 μm for the rabbit. 2) Estimates of ASL thickness at the end of the 40-min period, based on the final99mTc-DTPA concentration and the amount in the washout, were 42.9 μm for ferret and 45.4 μm for rabbit. 3) The ratio of Pto percent clearance gave mean ASL thickness values of 49.2 μm for the ferret and 40.3 μm for the rabbit. Thus three separate methods for determining ASL thickness give very similar results, with means in the range 40–49 μm. Administration of methacholine or atropine to ferret tracheae did not significantly change ASL thickness.

Osmolality alters tracheal blood flow and tracer uptake in anesthetized sheep

1994 ◽  
Vol 77 (5) ◽  
pp. 2400-2407 ◽  
Author(s):  
U. M. Wells ◽  
Z. Hanafi ◽  
J. G. Widdicombe
Keyword(s):  
Blood Flow ◽  
Water Movement ◽  
Venous Blood ◽  
Tracer Uptake ◽  
Solute Flux ◽  
Airway Surface Liquid ◽  
Tracheal Lumen ◽  
Airway Wall ◽  
Paracellular Pathways ◽  
Surface Liquid

Changes in the osmolality of airway surface liquid cause bronchoconstriction, mucus secretion, and ion transport, but little is known about the effects on the permeability of the trachea to drugs applied to the tracheal lumen. Using the anesthetized sheep, we have investigated the effects of hyperosmolar (725 +/- 11 mosmol/kg) and hyposmolar (128 +/- 5 mosmol/kg) Krebs-Henseleit (KH) solution in the tracheal lumen (mean volume 13.6 ml) on the uptake of technetium-99m-labeled diethylenetriamine pentaacetic acid (99mTc-DTPA), a low-molecular-mass hydrophilic tracer that is thought to cross the epithelium via paracellular pathways, and on blood flow. All changes in osmolality were made by altering the NaCl content. We perfused a tracheal artery and collected tracheal venous blood. Hyperosmolar KH increased water movement into the lumen (+2.0 ml) and solute flux out of the lumen. It increased arterial (+24.5%) and venous (+20.6%) flows and decreased 99mTc-DTPA concentration (-26.3%) and output (-12.0%) in venous blood. Hyposmolar KH caused water movement out of the lumen (-0.9 ml) and solute flux into the lumen. It had no effect on arterial (+0.6%) and venous (+5.5%) flows and greatly increased the concentration (+345%) and output (+375%) of 99mTc-DTPA in venous blood. The baseline permeability coefficient for 99mTc-DTPA (-9.1 x 10(-7) cm/s) was not affected by hyperosmolar KH (-8.7 x 10(-7) cm/s) but was increased by hyposmolar KH (-21.4 x 10(-7) cm/s). These results confirm that hyperosmolar liquid in the lumen increases blood flow and indicate that tracer uptake is affected by the bulk flow of water across the airway wall.

Proteomic analysis of the airway surface liquid: modulation by proinflammatory cytokines

2007 ◽  
Vol 292 (1) ◽  
pp. L185-L198 ◽  
Author(s):  
Giovanni Candiano ◽  
Maurizio Bruschi ◽  
Nicoletta Pedemonte ◽  
Luca Musante ◽  
Roberto Ravazzolo ◽  
...  
Keyword(s):  
Barrier Function ◽  
Cell Types ◽  
Mass Spectrometry Analysis ◽  
Surface Epithelium ◽  
Epithelial Barrier ◽  
Airway Surface Liquid ◽  
Epithelial Barrier Function ◽  
Spectrometry Analysis ◽  
Surface Liquid

The airway surface is covered by a fluid, the airway surface liquid, interposed between the mucous layer and the epithelium. The airway surface liquid contains proteins, secreted by different cell types, that may have pro-/anti-inflammatory or bactericidal functions or have a role in the mucociliary clearance. We have used a proteomics approach to identify the proteins secreted by an isolated in vitro model of human airway epithelium, at resting and under proinflammatory conditions, as a strategy to define the factors involved in epithelial barrier function. To this aim, we have analyzed the airway surface liquid from human bronchial epithelial cells grown as polarized monolayers in the presence and absence of inflammatory stimuli such as IL-4, IL-1β, TNF-α, and IFN-γ. Two-dimensional electrophoresis followed by mass spectrometry analysis has allowed the identification of ∼175 secreted protein spots, among which are immune-related proteins, structural proteins, an actin severer, some protease inhibitors, and a metalloproteinase. Comparisons between treated and untreated conditions have shown that the expression of several proteins was significantly modified by the different cytokines. Our results indicate that the surface epithelium is an active player in the epithelial barrier function and that inflammatory conditions may modulate protein secretion.

Sign in / Sign up

Export Citation Format

Share Document