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In vivo airway surface liquid Cl- analysis with solid-state electrodes.

Caldwell RA, Grubb BR, Tarran R, Boucher RC, Knowles MR, Barker PM - J. Gen. Physiol. (2002)

Bottom Line: 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 (approximately 30 microm) in vivo.In initial experiments, the electrode measured [Cl-] in physiologic salt solutions, small volume (7.6 microl) test solutions, and in in vitro cell culture models, with > or =93% accuracy.First, ASL [Cl-] was measured in normal human nasal cavity and averaged 117.3 +/- 11.2 mM (n = 6).

View Article: PubMed Central - PubMed

Affiliation: Cystic Fibrosis/Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. ray_caldwell@med.unc.edu

ABSTRACT
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 (approximately 30 microm) 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 microl) test solutions, and in in vitro cell culture models, with > or =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.

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Cl−-electrode sensor used for ASL Cl− measurements. (A) Cross-sectional view of the Ag/AgCl sensor and the air–surface liquid profile above airway epithelium is illustrated. ASL [Cl−] is obtained from the electrode voltage () developed from the electrochemistry at the electrode–electrolyte interface. The low impedance of the interface does not require the electrode to be totally immersed for Cl− measurement. The illustrated air–liquid radius of curvature is from confocal imaging (see below). The illustrated surface liquid height at the edge of the epithelium is from mouse trachea (Jayaraman et al. 2001a). For clarity, the PE-50 catheter containing the reference electrode is not shown. (B) Confocal image of the surface liquid–electrode interface. The electrode-induced radius of curvature was 373 μm.
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Figure 1: Cl−-electrode sensor used for ASL Cl− measurements. (A) Cross-sectional view of the Ag/AgCl sensor and the air–surface liquid profile above airway epithelium is illustrated. ASL [Cl−] is obtained from the electrode voltage () developed from the electrochemistry at the electrode–electrolyte interface. The low impedance of the interface does not require the electrode to be totally immersed for Cl− measurement. The illustrated air–liquid radius of curvature is from confocal imaging (see below). The illustrated surface liquid height at the edge of the epithelium is from mouse trachea (Jayaraman et al. 2001a). For clarity, the PE-50 catheter containing the reference electrode is not shown. (B) Confocal image of the surface liquid–electrode interface. The electrode-induced radius of curvature was 373 μm.

Mentions: The Cl−-electrode sensor is illustrated in Fig. 1 A. Both reference and sensor electrodes were prepared from Teflon-insulated Ag wire (bare wire diam, 127 μm × 99 cm; California Fine Wire). Approximately 2 mm of Teflon was removed from the wire ends for depositing the Cl−-sensing AgCl layer. The AgCl layer was deposited by immersing the wires in 5% (wt/vol) NaHClO3 solution for ∼20 min. Wires were rinsed with distilled, deionized water and allowed to dry for at least 5 h before use.


In vivo airway surface liquid Cl- analysis with solid-state electrodes.

Caldwell RA, Grubb BR, Tarran R, Boucher RC, Knowles MR, Barker PM - J. Gen. Physiol. (2002)

Cl−-electrode sensor used for ASL Cl− measurements. (A) Cross-sectional view of the Ag/AgCl sensor and the air–surface liquid profile above airway epithelium is illustrated. ASL [Cl−] is obtained from the electrode voltage () developed from the electrochemistry at the electrode–electrolyte interface. The low impedance of the interface does not require the electrode to be totally immersed for Cl− measurement. The illustrated air–liquid radius of curvature is from confocal imaging (see below). The illustrated surface liquid height at the edge of the epithelium is from mouse trachea (Jayaraman et al. 2001a). For clarity, the PE-50 catheter containing the reference electrode is not shown. (B) Confocal image of the surface liquid–electrode interface. The electrode-induced radius of curvature was 373 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2233861&req=5

Figure 1: Cl−-electrode sensor used for ASL Cl− measurements. (A) Cross-sectional view of the Ag/AgCl sensor and the air–surface liquid profile above airway epithelium is illustrated. ASL [Cl−] is obtained from the electrode voltage () developed from the electrochemistry at the electrode–electrolyte interface. The low impedance of the interface does not require the electrode to be totally immersed for Cl− measurement. The illustrated air–liquid radius of curvature is from confocal imaging (see below). The illustrated surface liquid height at the edge of the epithelium is from mouse trachea (Jayaraman et al. 2001a). For clarity, the PE-50 catheter containing the reference electrode is not shown. (B) Confocal image of the surface liquid–electrode interface. The electrode-induced radius of curvature was 373 μm.
Mentions: The Cl−-electrode sensor is illustrated in Fig. 1 A. Both reference and sensor electrodes were prepared from Teflon-insulated Ag wire (bare wire diam, 127 μm × 99 cm; California Fine Wire). Approximately 2 mm of Teflon was removed from the wire ends for depositing the Cl−-sensing AgCl layer. The AgCl layer was deposited by immersing the wires in 5% (wt/vol) NaHClO3 solution for ∼20 min. Wires were rinsed with distilled, deionized water and allowed to dry for at least 5 h before use.

Bottom Line: 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 (approximately 30 microm) in vivo.In initial experiments, the electrode measured [Cl-] in physiologic salt solutions, small volume (7.6 microl) test solutions, and in in vitro cell culture models, with > or =93% accuracy.First, ASL [Cl-] was measured in normal human nasal cavity and averaged 117.3 +/- 11.2 mM (n = 6).

View Article: PubMed Central - PubMed

Affiliation: Cystic Fibrosis/Pulmonary Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. ray_caldwell@med.unc.edu

ABSTRACT
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 (approximately 30 microm) 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 microl) test solutions, and in in vitro cell culture models, with > or =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.

Show MeSH
Related in: MedlinePlus