In Vitro Airway Responsiveness of Flinders Sensitive and Resistant Line Rats

• Published in: Brain, behavior, and immunity behavior, and immunity, 2000-03, Vol.14 (1), p.62-67
• Main Authors: Janssen, L.J., Djuric, V.J., Wattie, J., Otis, J., O'Byrne, P.M.
• Format: Article
• Language: English
• Subjects: Airway Resistance - drug effects; Airway Resistance - genetics; airway smooth muscle; allergen-induced inflammation; Allergens - pharmacology; Allergens - toxicity; Animals; Bronchi - drug effects; Bronchial Hyperreactivity - chemically induced; Bronchial Hyperreactivity - genetics; Bronchoconstriction - drug effects; Bronchoconstriction - genetics; Bronchoconstrictor Agents - pharmacology; Carbachol - pharmacology; Cholinergic Agents - pharmacology; cholinergic innervation; Electric Stimulation; Female; Key Words: Flinders rats; Muscle, Smooth - drug effects; Muscle, Smooth - innervation; Ovalbumin - pharmacology; Ovalbumin - toxicity; Parasympathetic Nervous System - physiology; Potassium Chloride - pharmacology; Rats; Rats, Inbred Strains - physiology; Respiratory Function Tests; Trachea - drug effects
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1006/brbi.1999.0573

Recently, we reported that freely moving Flinders sensitive line rats (FSL, selectively bred for their cholinergic hyperresponsiveness) are more susceptible to allergen-induced airway hyperresponsiveness than their control counterparts—Flinders resistant line (FRL) rats. In this study the two Flinders lines were compared for responsiveness of excised tracheal and primary bronchial smooth muscle in vitro. FSL tissues were slightly but significantly more sensitive to cholinergic stimulation than FRL tissues (slightly lower EC50 value for carbachol) but the FRL tissues were more responsive, exhibiting larger amplitude of response. Surprisingly, previous exposure to allergen challenge was accompanied by reduced in vitro responses to spasmogens in both rat lines. We conclude that FSL and FRL airways do not differ greatly with respect to sensitivity to cholinergic stimulation in vitro and that inflamed airways show reduced in vitro responses to spasmogens. The discrepancy between the in vivo and in vitro findings suggests that responsiveness of airway smooth muscle involves regulation from both proximal and distal sites.