title: Effect of osmolality on mucociliary transportability and rheology of cystic fibrosis and bronchiectasis sputum.
abstract: OBJECTIVE
  Water is the main constituent of mucus, and its concentration is likely to be important in all aspects of mucus function, including ciliary clearance. The objective of this study was to investigate the effect of water content and osmolality of the mucus on mucociliary transportability.
  
  
  METHODS
  Rheology and ciliary transportability of 10 sputum samples that had been subjected to various manipulations were measured using a mucus-depleted bovine trachea model.
  
  
  RESULTS
  It was shown that addition of sodium chloride 0.2 Osmoles/kg (0.585% weight for weight) increased the transportability by 41% (P < 0.01). Evaporation of the sputum to 50% of its original weight caused a 118% increase in transportability (P < 0.0006), but iso-osmolal removal of 50% of the liquid with filter cards led to a non-significant, 25% increase in transportability. Parallel plate viscoelasticity was approximately doubled in both the evaporated and liquid-depleted samples, but was not changed by the addition of 0.2 Osmoles/kg of sodium chloride. The correlation between the osmolality of sputum and ciliary transportability (r = 0.54, P= 0.005) was better than the correlations between the viscosity (r = 0.21, P= 0.27) or elasticity (r = 0.23, P= 0.23) and ciliary transportability.
  
  
  CONCLUSIONS
  These results suggest that the osmolality of sputum exerts a greater influence on mucociliary clearance than its viscoelastic properties.
authors.affiliation: Host Defence Unit, Royal Brompton National Heart and Lung Institute, Imperial College, London, UK. shibuyay@hiroo-hospital.metro.tokyo.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shibuya
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Wills
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Cole
mesh_terms: D001987:Bronchiectasis / Q000503:physiopathology*; D003550:Cystic Fibrosis / Q000503:physiopathology*; D004548:Elasticity; D006801:Humans; D009079:Mucociliary Clearance / Q000502:physiology*; D009093:Mucus / Q000502:physiology*; D009994:Osmolar Concentration; D012212:Rheology; D013183:Sputum / Q000502:physiology*; D014783:Viscosity