Absence of cholinergic airway tone in normal BALB/c mice.
Basal airway smooth muscle (ASM) tone has not been demonstrated in mice in vivo. To determine whether basal ASM tone is present in mouse airways we measured respiratory system impedance (Zrs) before and after either atropine or bilateral vagotomy. Zrs was measured using forced oscillations delivered via a wave-tube during slow ( approximately 35s) inflation-deflation maneuvers between transrespiratory pressures (Prs) of 0 and 20 cm H2O. A constant-phase tissue model was applied to the Zrs to calculate airway resistance (R aw), tissue damping (G) and elastance (H). Thoracic gas volume (TGV) was determined plethysmographically at Prs=0 cm H2O and by integration of the inspiratory flow. The relationship between conductance (G aw=1/R aw) and TGV during inflation was also examined. Neither atropine nor vagotomy produced any change in R aw, H, eta (=G/H), TGV or the slope of G aw vs. TGV that was different to that observed in the relevant control groups. These data show that BALB/c mice do not have cholinergic ASM tone in vivo.
Larcombe
Alexander N
AN
Division of Clinical Sciences, Telethon Institute for Child Health Research & Centre for Child Health Research, University of Western Australia, Perth, Australia.
Zosky
Graeme R
GR
Bozanich
Elizabeth M
EM
Turner
Debra J
DJ
Hantos
Zoltan
Z
Sly
Peter D
PD
D000109:Acetylcholine / Q000378:metabolism*; D000403:Airway Resistance / Q000187:drug effects / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D005260:Female; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010992:Plethysmography, Impedance / Q000379:methods; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology*; D012737:Sex Factors; D014109:Total Lung Capacity / Q000187:drug effects / Q000502:physiology*; D014628:Vagotomy / Q000379:methods
D018727:Muscarinic Antagonists; D001285:Atropine; D000109:Acetylcholine