Comparison of non-invasive measures of cholinergic and allergic airway responsiveness in rats.
OBJECTIVE
Non-invasive analysis of tidal expiratory flow parameters such as Tme/TE (time needed to reach peak expiratory flow divided by total expiratory time) or midexpiratory tidal flow (EF50) has been shown useful for phenotypic characterization of lung function in humans and animal models. In this study, we aimed to compare the utility of two non-invasive measures, EF50 and Tme/TE, to monitor bronchoconstriction to inhaled cholinergic and allergic challenges in Brown-Norway rats.


METHODS
Non-invasive measurements of Tme/TE and EF50 were paralleled by invasive recordings of Tme/TE, EF50 and pulmonary conductance (GL).


RESULTS
First, dose-response studies with acetylcholine were performed in naive rats, showing that EF50 better than Tme/TE reflected the dose-related changes as observed with the classical invasive outcome parameter GL. The subsequent determination of allergen-specific early airway responsiveness (EAR) showed that ovalbumin-sensitized and -challenged rats exhibited airway inflammation and allergen-specific EAR. Again, EF50 was more sensitive than Tme/TE in detecting the allergen-specific EAR recorded with invasive and non-invasive lung function methods and agreed well with classical GL measurements.


CONCLUSIONS
We conclude that non-invasive assessment of EF50 is significantly superior to Tme/TE and serves as a suitable and valid tool for phenotypic screening of cholinergic and allergic airway responsiveness in rats.
Glaab
T
T
Fraunhofer Institute of Toxicology and Experimental Medicine, Hannover, Germany.
Hecker
H
H
Stephan
M
M
Baelder
R
R
Braun
A
A
Korolewitz
R
R
Krug
N
N
Hoymann
H G
HG
D000109:Acetylcholine; D000403:Airway Resistance; D000485:Allergens; D000818:Animals; D018678:Cholinergic Agents; D004305:Dose-Response Relationship, Drug; D008297:Male; D023421:Models, Animal; D010047:Ovalbumin; D010991:Plethysmography; D051381:Rats; D011914:Rats, Inbred BN; D012129:Respiratory Function Tests; D012130:Respiratory Hypersensitivity / Q000175:diagnosis*
D000485:Allergens; D018678:Cholinergic Agents; D010047:Ovalbumin; D000109:Acetylcholine