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Lipopolysaccharide-induced airway hyporeactivity to methacholine in guinea pigs in vivo is absent in the isolated, perfused trachea in vitro.

Authors
Johnston-RA; Olson-SG; Fedan-JS
Source
FASEB J 2000 May; 14(8):A1497
NIOSHTIC No.
20020971
Abstract
This study examined the effects of lipopolysaccharide (LPS)-treatment (4 mg/kg, i.p., 18 hr post-exposure) on guinea pig reactivity to methacholine (MCh) in vivo and in vitro. In vivo airway reactivity to MCh was measured by placing conscious, guinea pigs in a two-chamber whole body plethysmograph for measuring specific airway resistance (SRaw) and exposing them to increasing concentrations of MCh aerosol. In LPS-treated animals, the basal SRaw was increased compared to that in the saline injected control animals. In addition, the LPS-treated animals were hyporeactive to inhaled MCh. Airway reactivity in vitro was measured using the isolated, perfused trachea preparation to permit MCh addition separately to the serosal (extraluminal; EL) or mucosal (intraluminal; IL) surfaces; because of the epithelium, EL reactivity to MCh is greater than IL reactivity. In epithelium-intact tracheas there was no difference in the EC50 values for contraction to EL and IL MCh between control- and LPS-treated guinea pigs. In epithelium-denuded tracheas where the difference between EL and IL reactivity was abolished, LPS-treatment had no effect on reactivity to MCh. These results suggest that the hyporeactivity observed in vivo does not involve the trachea or the mechanism(s) is lost in vitro.
Keywords
Methacholines; Laboratory-animals; Animals; Animal-studies; In-vivo-studies; In-vitro-studies; Exposure-levels; Airway-resistance; Aerosols
CODEN
FAJOEC
Publication Date
20000511
Document Type
Abstract; Conference/Symposia Proceedings
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Issue of Publication
8
ISSN
0892-6638
NIOSH Division
HELD
Source Name
The FASEB Journal
State
WV
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