Pulmonary gas trapping in the guinea pig and its application in pharmacological testing

Airway constriction produced by bronchoconstrictive aerosols in vivo can result in substantial postmortem pulmonary gas trapping in the guinea pig. In order to use gas trapping responses for the evaluation of potential antiasthma agents, we developed a multiple animal inhalation exposure apparatus and an accurate system for quantitating excised lung gas volumes in the guinea pig. Aerosols of histamine, methacholine, and leukotriene D4 were shown to produce gas trapping responses that were inhibited in a dose-dependent fashion by appropriate antagonists. The approach described provides an objective and sensitive measure of the severity of airway obstruction, does not require surgery or anesthesia, and allows excellent control of unwanted sources of experimental variation.