期刊
JOURNAL OF PHYSIOLOGY-LONDON
卷 586, 期 22, 页码 5537-5547出版社
WILEY
DOI: 10.1113/jphysiol.2008.159822
关键词
-
资金
- NHMRC of Australia
- Hong Kong Lung Foundation Fellowship
Pharyngeal patency is influenced by the surface tension (gamma) of the upper airway lining liquid (UAL), of which saliva is a major component. We investigated the influences of saliva production on gamma of the UAL, and upper airway re-opening and closing pressures. In 10 supine, male, anaesthetized, tracheostomised, mechanically ventilated New Zealand White rabbits, we measured re-opening and closing of the passive isolated upper airway at baseline and following graded (cumulative) doses of methacholine or atropine. Upper airway liquid volume index (UALVI) was assessed using a standardized suction procedure (secretion weight obtained per second) expressed as the natural logarithm (LnUALVI). The gamma of UAL samples were measured using the 'pull-off' force technique. Across all animals, baseline values were: LnUALVI -6.2 (-8.6 to -5.4) median (interquartile range), gamma of UAL 58.9 (56.6-59.9) mN m(-1), re-opening 8.6 (6.9-11.1) cmH(2)O, and closing pressures 3.2 (1.8-5.7) cmH(2)O. LnUALVI increased by similar to 0.17 per mu g kg(-1) methacholine and decreased by similar to 0.14 per 100 mu g kg(-1) atropine (both P < 0.03, linear mixed effects modelling). Surface tension was unchanged by methacholine but increased by similar to 0.6 mN m(-1) per 100 mu g kg(-1) atropine (P < 0.004). When data were analysed across all animals, both re-opening and closing pressures increased as surface tension increased (by similar to 0.4 cmH(2)O mN(-1) and by similar to 0.7 cmH(2)O mN(-1), respectively; both P < 0.05). We conclude that saliva production influences upper airway mechanical properties partly via alterations in gamma of UAL. We speculate that in obstructive sleep apnoea, altered autonomic activity may reduce saliva production and increase surface tension of the upper airway lining liquid, thus increasing the likelihood of upper airway obstruction.
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