Methacholine-induced pulmonary gas trapping in the guinea pig, hamster, mouse and rat. Stengel, Peter W., Carmen A. Yiamouyiannis, Robert L. Obenchain, Sandra L. Cockerham, and Steven A. Silbaugh. Eli Lilly and Company, Cardiovascular Research, Lilly Corporate Center, Indianapolis, IN 46285, U.S.A.
APStracts 2:0328A, 1995.
Postmortem pulmonary gas trapping was investigated as an index of in vivo airway obstruction following methacholine inhalation in 4 different rodent species. Male guinea pigs (Hartley), hamsters (Golden Syrian), mice (A/J, BALB/c and ICR) and rats (Brown-Norway, Fischer 344, Lewis and Sprague-Dawley) were exposed to aerosols of methacholine or sodium chloride. Maximum excised lung gas volumes (ELGV) of methacholine-exposed guinea pigs, hamsters, mice and rats were 2.3 to 8.7 times those of sodium chloride-treated animals. Mean ELGV values of sodium chloride-exposed animals ranged from 1.50 + 0.20 ml/kg for guinea pigs to 2.75 + 0.20 ml/kg for Brown-Norway rats. Although all species responded to methacholine, guinea pigs were the most responsive with approximately 1.6 [mu]g/kg of inhaled methacholine needed to increase ELGV to 200% of control. Compared to guinea pigs, hamsters, mice and rats were 11 to 1395 fold less responsive. Although hamsters, mice and rats are less sensitive than guinea pigs to the airway obstructive effects of methacholine, pulmonary gas trapping appears useful as a measure of airway responses in these species. 

Received 11 November 1994; accepted in final form 17 July 1995.
APS Manuscript Number A1157-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.