Noninvasive in vivo fluorescence measurement of airway-surface liquid depth, salt concentration, and pH

Jayaraman, Sujatha; Song, Yuanlin; Vetrivel, L.; Shankar, Leena; Verkman, A. S.

doi:10.1172/jci11154

Cited by 199 publications

(187 citation statements)

References 31 publications

Supporting

Mentioning

170

Contrasting

Unclassified

Order By: Relevance

“…Similarly, elevated NaCl concentrations have been reported in CF airway fluids (19). However, it has then been shown that airway-surface liquid in CFTR-null mice is approximately isotonic (20) and that submucosal gland secretions in airways from patients with CF have normal [Na + ], although presenting elevated viscosity (21). Contrary to α7 nAChR, absence of either α5, β2, or β4 nAChR subunit does not impact on airway mucus transport in mice (Fig.…”

Section: Resultsmentioning

confidence: 97%

Contribution of α7 nicotinic receptor to airway epithelium dysfunction under nicotine exposure

Maouche

Medjber

Zahm

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Loss or dysfunction of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) leads to impairment of airway mucus transport and to chronic lung diseases resulting in progressive respiratory failure. Nicotinic acetylcholine receptors (nAChRs) bind nicotine and nicotine-derived nitrosamines and thus mediate many of the tobacco-related deleterious effects in the lung. Here we identify α7 nAChR as a key regulator of CFTR in the airways. The airway epithelium in α7 knockout mice is characterized by a higher transepithelial potential difference, an increase of amiloride-sensitive apical Na + absorption, a defective cAMP-dependent Cl − conductance, higher concentrations of Na + , Cl − , K + , and Ca 2+ in secretions, and a decreased mucus transport, all relevant to a deficient CFTR activity. Moreover, prolonged nicotine exposure mimics the absence of α7 nAChR in mice or its inactivation in vitro in human airway epithelial cell cultures. The functional coupling of α7 nAChR to CFTR occurs through Ca 2+ entry and activation of adenylyl cyclases, protein kinase A, and PKC. α7 nAChR, CFTR, and adenylyl cyclase-1 are physically and functionally associated in a macromolecular complex within lipid rafts at the apical membrane of surface and glandular airway epithelium. This study establishes the potential role of α7 nAChR in the regulation of CFTR function and in the pathogenesis of smoking-related chronic lung diseases.chloride efflux | ciliated cell | mouse | mucociliary clearance | submucosal gland

show abstract

Section: Resultsmentioning

confidence: 97%

Contribution of α7 nicotinic receptor to airway epithelium dysfunction under nicotine exposure

Maouche

Medjber

Zahm

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Among the limited number of Na + sensors, such as sodium-binding benzofuran isophthalate (22), Sodium Green (23), CoroNa Green/Red (24,25), and Asante NaTRIUM Green-1/2 (26), most of them are not selective for Na + over K + (22-25, 27, 28) or have a low binding affinity for Na + (with a K d higher than 100 mM) (25,(27)(28)(29)(30)(31). Furthermore, the presence of organic solvents is frequently required to achieve the desired sensitivity and selectivity for many of the Na + probes (32)(33)(34), making it difficult to study Na + under physiological conditions.…”

mentioning

confidence: 99%

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Torabi¹,

Wu²,

McGhee³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

316

286

View full text Add to dashboard Cite

Over the past two decades, enormous progress has been made in designing fluorescent sensors or probes for divalent metal ions. In contrast, the development of fluorescent sensors for monovalent metal ions, such as sodium (Na + ), has remained underdeveloped, even though Na + is one the most abundant metal ions in biological systems and plays a critical role in many biological processes. Here, we report the in vitro selection of the first (to our knowledge) Na + -specific, RNA-cleaving deoxyribozyme (DNAzyme) with a fast catalytic rate [observed rate constant (k obs ) ∼0.1 min −1 ], and the transformation of this DNAzyme into a fluorescent sensor for Na + by labeling the enzyme strand with a quencher at the 3′ end, and the DNA substrate strand with a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of Na + catalyzed cleavage of the substrate strand at an internal ribonucleotide adenosine (rA) site, resulting in release of the fluorophore from its quenchers and thus a significant increase in fluorescence signal. The sensor displays a remarkable selectivity (>10,000-fold) for Na + over competing metal ions and has a detection limit of 135 μM (3.1 ppm). Furthermore, we demonstrate that this DNAzyme-based sensor can readily enter cells with the aid of α-helical cationic polypeptides. Finally, by protecting the cleavage site of the Na + -specific DNAzyme with a photolabile o-nitrobenzyl group, we achieved controlled activation of the sensor after DNAzyme delivery into cells. Together, these results demonstrate that such a DNAzyme-based sensor provides a promising platform for detection and quantification of Na + in living cells.M etal ions play crucial roles in a variety of biochemical processes. As a result, the concentrations of cellular metal ions have to be highly regulated in different parts of cells, as both deficiency and surplus of metal ions can disrupt normal functions (1-4). To better understand the functions of metal ions in biology, it is important to detect metal ions selectively in living cells; such an endeavor will not only result in better understanding of cellular processes but also novel ways to reprogram these processes to achieve novel functions for biotechnological applications.Among the metal ions in cells, sodium (Na + ) serves particularly important functions, as changes in its concentrations influence the cellular processes of numerous living organisms and cells (5-8), such as epithelial and other excitable cells (9). As one of the most abundant metal ions in intracellular fluid (10), Na + affects cellular processes by triggering the activation of many signal transduction pathways, as well as influencing the actions of hormones (11). Therefore, it is important to carefully monitor the concentrations of Na + in cells. Toward this goal, instrumental analyses by atomic absorption spectroscopy (12), Xray fluorescence microscopy (13), and 23 Na NMR (14) have been used to detect the concentration of intracellular Na + . However, it is difficult to use these methods to o...

show abstract

“…Although early data suggested that salt concentration in the ASL is low in normal airways (4), the current view is that the ASL is approximately isotonic in both normal and CF airways (5)(6)(7). A concern with older measurements of ASL composition involving fluid collection by filter paper or microcapillaries is perturbation of the airway surface and the sampling, by capillary forces, of more fluid than contained in the very thin (tens of microns) ASL layer.…”

mentioning

confidence: 99%

“…Studies using ion-sensitive microelectrodes, although technically demanding and requiring direct contact with the ASL, provided evidence for a nearly isotonic ASL (5). Our laboratory developed ratioable fluorescent dyes to measure ASL [Na ϩ ] and [Cl Ϫ ], in which the ASL was fluorescently stained for determination of ion concentrations by ratio imaging microscopy (7). ASL salt concentration ([Na ϩ ] and [Cl Ϫ ]) was found to be approximately isotonic in airway epithelial cell cultures, mouse trachea and small airways, and ex vivo human airways, without differences in CFTR deficiency (7,8).…”

mentioning

confidence: 99%

“…Our laboratory developed ratioable fluorescent dyes to measure ASL [Na ϩ ] and [Cl Ϫ ], in which the ASL was fluorescently stained for determination of ion concentrations by ratio imaging microscopy (7). ASL salt concentration ([Na ϩ ] and [Cl Ϫ ]) was found to be approximately isotonic in airway epithelial cell cultures, mouse trachea and small airways, and ex vivo human airways, without differences in CFTR deficiency (7,8). We also found the ASL to be approximately isosmolar with serum using fluorescent, osmotically sensitive liposomes (9).…”

mentioning

confidence: 99%

See 1 more Smart Citation

In Situ Measurement of Airway Surface Liquid [K+] Using a Ratioable K+-sensitive Fluorescent Dye

Namkung

Song

Mills

et al. 2009

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Noninvasive in vivo fluorescence measurement of airway-surface liquid depth, salt concentration, and pH

Cited by 199 publications

References 31 publications

Contribution of α7 nicotinic receptor to airway epithelium dysfunction under nicotine exposure

Contribution of α7 nicotinic receptor to airway epithelium dysfunction under nicotine exposure

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

In Situ Measurement of Airway Surface Liquid [K+] Using a Ratioable K+-sensitive Fluorescent Dye

Contact Info

Product

Resources

About