Noninvasive measurement of midexpiratory flow indicates bronchoconstriction in allergic rats.
This study was designed to evaluate the value and applicability of tidal breathing pattern analysis to assess bronchoconstriction in conscious rats. Using noninvasive, head-out body plethysmography and the decrease in tidal midexpiratory flow (EF(50)), we measured airway responsiveness (AR) to inhaled acetylcholine and allergen in conscious Brown-Norway rats, followed by invasive determination of pulmonary conductance (GL) and EF(50) in anesthetized rats. Dose-response studies to acetylcholine showed that noninvasively recorded EF(50) closely reflected the dose-dependent decreases observed with the invasive monitoring of simultaneously measured GL and EF(50). After sensitization and intratracheal boost to ovalbumin or saline, rats were assessed for early and late AR to aerosolized ovalbumin. Ovalbumin aerosol challenge resulted in early and late AR in allergen-sensitized rats, whereas controls were unresponsive. The allergen-specific AR, as measured noninvasively by EF(50), was similar in degree compared with invasively recorded EF(50) and GL and was associated with enhanced IgE and airway inflammation. We conclude that EF(50) is a noninvasive and physiologically valid index of bronchoconstriction in a rat model of asthma.
Glaab
Thomas
T
Department of Respiratory Medicine, Hannover Medical School, 30625 Hannover, Germany. thomasglaab@web.de
Hoymann
Heinz G
HG
Hohlfeld
Jens M
JM
Korolewitz
Regina
R
Hecht
Matthias
M
Alarie
Yves
Y
Tschernig
Thomas
T
Braun
Armin
A
Krug
Norbert
N
Fabel
Helmut
H
D000109:Acetylcholine / Q000494:pharmacology; D000280:Administration, Inhalation; D000485:Allergens / Q000276:immunology / Q000494:pharmacology; D000818:Animals; D016084:Bronchoconstriction; D002245:Carbon Dioxide / Q000494:pharmacology; D006967:Hypersensitivity / Q000276:immunology / Q000503:physiopathology*; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D010047:Ovalbumin / Q000276:immunology / Q000494:pharmacology; D010991:Plethysmography; D012123:Pulmonary Ventilation; D051381:Rats; D011914:Rats, Inbred BN; D012119:Respiration; D012137:Respiratory System / Q000187:drug effects
D000485:Allergens; D002245:Carbon Dioxide; D010047:Ovalbumin; D000109:Acetylcholine