PT  - JOURNAL ARTICLE
AU  - JH Widdicombe
AU  - SJ Bastacky
AU  - DX Wu
AU  - CY Lee
TI  - Regulation of depth and composition of airway surface liquid
AID  - 10.1183/09031936.97.10122892
DP  - 1997 Dec 01
TA  - European Respiratory Journal
PG  - 2892--2897
VI  - 10
IP  - 12
4099  - http://erj.ersjournals.com/content/10/12/2892.short
4100  - http://erj.ersjournals.com/content/10/12/2892.full
SO  - Eur Respir J1997 Dec 01; 10
AB  - The depth and composition of human airway surface liquid (ASL) may depend on secretion from airway glands, ion transport across the surface epithelium, goblet cell discharge, transepithelial gradients in hydrostatic pressure, and surface tension. Published values for the frequency of airway glands and for the secretory rates of individual glands suggest that total gland secretion in human trachea can amount to approximately 60 microL x cm(-2) x h(-1). Volume absorption directly measured across cultures of surface epithelium from human trachea is approximately 5 microL x cm(-2) x h(-1). These flows should alter the depth of ASL at +10 and -1 microm x min(-1). We have looked for changes in ASL depth of this magnitude using low-temperature scanning electron microscopy (LT-SEM) of rapidly frozen specimens of bovine trachea. Stimulation of gland secretion with methacholine led to an initial increase in depth of approximately 25 microm x min(-1) followed by a decline at approximately 1.5 microm x min(-1). Whereas the initial increase in depth was probably due to transient gland secretion, the later decline reflected active absorption of liquid across the surface epithelium. Finally, we present preliminary data showing that LT-SEM can be combined with X-ray microanalysis to determine the elemental composition of ASL.